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Articles from 1999 In July


Hollow-shaft stepper



Motors

Hollow-shaft stepper

A hollow-shaft stepper allows access for electrical and optical cables through the central axis of the motor. The 2.25-in.-diam motor is bidirectional and based on a 1.8° step with noncumulative position accuracy of ±3%. The peak torque rating is 50 oz-in. Other features include permanently lubricated high-precision ball bearings and a range of windings to match a variety of unipolar and bipolar drives. Eastern Air Devices Inc., 1 Progress Dr., Dover, NH 03820-5449.




Zero-cog motors

According to the manufacturer, a combination of a slotted stator with a rotor design results in a line of ac brushless motors that are virtually cog-free. Specifications for the PSA series include optional IEC frames, power ratings of 230 or 400 V ac, and a rated torque from 0.76 to 20.9 N·m. API Motion Inc., 45 Hazelwood Dr., Amherst, NY 14228-2096.




Brushless dc motors

Featuring slotless construction to prevent magnetic cogging, brushless dc motors offer long life. Slotless design also reduces inductance, improving current bandwidth for increased control and acceleration. Elcom II brushless motors are available in three frame sizes and can be customized with Hall sensor feedback for six-step commutation at 60 electrical degrees. Integrated Hewlett-Packard optical encoders can be incorporated for reliable position, velocity, and direction feedback. Pittman, 343 Godshall Dr., Harleysville, PA 19438-0003.




Replacement motor

A 3-in.-OD brushless dc motor has an operating life of more than 20,000 hours and is available in 12- and 24-V models. Designed as a two-wire drop-in replacement for brush-type dc motors, the DurA-tek 3.0 offers a two-wire electrical hookup. Other features include multispeed operation, over-temperature shutoff, and transient overvoltage protection. The motors offer both internal and external controls, and are available in heights of 5.19 and 4.27 in. Ametek, Rotron Technical Motor Div., 627 Lake St., Kent, OH 44240.




Dc motor

Suitable for use in handheld surgical tools and dental equipment, a brushless dc motor enables precise speed control. The size-5 MediTorq is constructed of stainless steel and offers speeds up to 100,000 rpm. The motor can be equipped with a hollow shaft for irrigation needs, planetary gearheads for increased torque and reduced speeds, and threaded housing and shafts for attachment to equipment. Transicoil Medical LLC, 2560 General Armistead Ave., Norristown, PA 19403-5214.




Miniature motor

A 0.007-in.-diam brushless motor and planetary gearhead is the world's smallest available gearmotor, according to its manufacturer. The BL 1900 series uses a bipolar rare-earth permanent magnet for the motor rotor, Liga cast gears in its gearhead, and a sensorless electronic commutation system, resulting in a continuous output torque of 0.02 oz-in. and an intermittent output torque of 0.042 oz-in. The motor is capable of input speeds of 20,000 rpm and continuous output speeds of 100,000 rpm. MicroMo Electronics Inc., 14881 Evergreen Dr., Clearwater, FL 33762-3008.




Stainless and paint-free motors

For applications that require sanitary and sterile conditions, a company manufactures stainless and paint-free ac and dc motors. Also offered are low- and standard-inertia brushless servomotors with a torque range from 3.9 to 366 lb-in. and 14.4 to 177 lb-in., respectively. The company also produces a line of linear motors for the medical device industry. Baldor Electric Co., P.O. Box 2400, Fort Smith, AR 72902-2400.




Servomotor

A brushless servomotor has a continuous stall torque rating of 15 oz-in. and a peak rating of 72 oz-in. at 6000 rpm. The AVS-M172 motor has a 1000-line encoder that measures 1.7 x 1.7 x 2.56 in. The motor can be driven by the company's digital ac servo drive system, which uses sine wave vector commutation to produce smooth motion without torque or velocity ripple. The Advanced Vector Servo system, which performs closed-loop speed and position control using step and direction signals, can replace a stepper system. Bearing Engineers Inc., 27 Argonaut, Aliso Viejo, CA 92656.




Rotary servomotors

A line of rotary servomotors features a magnetic circuit, thermal management, and winding design, which provides the maximum copper fill per slot and low thermal resistance. MFM rotary servomotors produce 114-in.-lb continuous torque and 340-in.-lb peak torque. NEMA frame sizes 17, 23, 34, and 42 and four frame sizes ranging from 40 to 115 mm are available. An optional resolver and brake can be installed along with standard steel disc encoders. Bayside Motion Group, 27 Seaview Blvd., Port Washington, NY 11050.




Brushless motor

A brushless dc motor with integrated electronics offers 10,000 to 20,000 hours operating life and 10 to 60 W output power. Options include integrated closed-loop speed control circuitry and a variety of planetary gearboxes. The motors are suitable for electromedical applications such as dialysis machines, analyzers, pumps, and portable systems. Crouzet Corp., 3237 Commander, Carrollton, TX 75006.




Compact motor

A direct-drive motor features an interchangeable control unit and motor, built-in autotuning, high resolution, full closed-loop control, and zero backlash. The JS series Megatorque motor has a hollow structure that allows for the insertion of wires or pipes. Specifications for the four models include a repeatability of ±2.1 to ±3.2 arc/sec, torque range from 1.5 to 10.3 ft-lb, and diam between 75 and 130 mm. NSK Corp., Precision Products Div., 250 Covington Dr., Bloomingdale, IL 60108-3106.




Dc motor

Specifically designed to withstand autoclave sterilization, a 1.1-in. diam brushless dc motor is suitable for use in battery-powered, handheld surgical devices. The N11 series motor features a cannulated shaft for insertion of a pin or wire and eight pins for connection to a brushless motor controller. Specifications include continuous torque of 10 oz/in. and speeds in excess of 30,000 rpm. The series is compatible with the company's size 13 planetary gearboxes, clutches, and brakes. Astromec Inc., 2950 Arrowhead Dr., Carson City, NV 89706-0488.




Custom motors

A company offers custom-fabricated brushless dc motors with built-in controllers for use in medical applications. Materials used include neodymium, iron, boron, samarium cobalt, and Hyperco 50. Depending upon temperature requirements, the company can use either plastic or ceramic chips. Brushless rotor and stator kits are also available. Arc Systems Inc., 2090 Joshuas Path, Hauppauge, NY 11788.




Stepper motor

Incorporating a multifunctional, inside-out hollow-core design, a motor can be converted into a ball-screw linear actuator by mounting a miniature ball-screw to its front shaft face. A hollow shaft in the 34 frame IOS motor allows electrical or pneumatic lines to be directed through its center, enabling the stacking of more than one motor. The through hole is stationary to prevent cables from being chaffed by a moving hollow shaft. Operating speed can reach 3000 rpm. The motor is compatible with bipolar chopper microstepping drivers. Intelligent Motion Systems Inc., P.O. Box 457, Marlborough, CT 06447.




Dc motors

A line of brushless dc motors produces low cogging torque and is suitable for a variety of applications including pumps, blowers, centrifuges, and high-speed scanners. Performance specifications include speeds up to 20,000 rpm, a continuous stall torque of more than 32 oz-in., and peak torque of 100 oz-in. Permanently lubricated, double-shielded ball bearings are standard. High-energy bonded neodymium and bonded samarium cobalt magnets are available depending on application and temperature requirements. Servo Magnetics Inc., 6660 Variel Ave., Canoga Park, CA 91303.




Linear servomotors

A company offers a series of directly driven, brushless linear servomotors with a high-efficiency magnetic circuit design. The BLM, BLMC, BLMUC, BLMH, and BLMX series motors comprise a moving forcer coil and a u-channel rare-earth magnet track, both noncontacting parts. A stackable magnet track system with a symmetrical mounting-hole pattern allows for unlimited travel lengths. Continuous force ratings range from 8.2 to 1183 lb, with peak force ratings from 33 to 1064 lb. Aerotech Inc., 101 Zeta Dr., Pittsburgh, PA 15238.




Coil motor

A 12-mm-diam rhombic moving coil motor incorporates an ironless rotor, which allows for zero cogging and accurate control. The A-max motor is available with a single or passing shaft and has ratings of 0.5 or 0.75 W. Other standard options include ball bearings, sleeve bearings, terminals, and leads. Matching gearheads with ratios ranging from 4:1 to 1118:1 can deliver up to 75 oz-in. of intermittent torque. Maxon Precision Motors Inc., 838 Mitten Rd., Burlingame, CA 94010.




High-speed motor

With a peak output of 176 W, a brushless dc motor is suitable for use in surgical and dental handpieces, small grinders, and engravers. The 23A103 motor features slotless construction, high-energy rare-earth magnets, and 40,000 rpm no-load speed with a no-load current of 150 mA. A high-cycle autoclavable version is available. Optional features include planetary gearboxes and encoders. Koford Engineering, 1948 University Ln., Lisle, IL 60532.




Induction motors

Terminal box-type ac induction motors allow a power cable to be fixed with the cable clamp and seal connector for security purposes. Because the lead wires are inserted directly into the terminal block, terminal crimping is not required. The series includes motors with 25-, 40-, 60-, and 90-W output power; 100 V ac, 50/60 Hz to 230 V ac, 50/60 Hz input power; and gearhead ratios from 3:1 to 180:1. All products conform to UL, CSA, and EN standards. Oriental Motor U.S.A. Corp., 2510 W. 237th St., Torrance, CA 90505.



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Copyright ©1999 Medical Product Manufacturing News

Products from the Cover of MPMN

Products from the Cover of MPMN

Mass flowmeters

TSI Inc. (St. Paul, MN) Series 4000 flowmeters measure mass flow, volume, temperature, and pressure. Features include high accuracy (2% of reading), a fast response time of 4 milliseconds, and low pressure drop of 2 cm H2O at 100 slm. Applications include prototyping and production testing of ventilators, anesthesia systems, metabolic monitors, spirometers, and other cardiorespiratory devices.



Diode-pumped lasers

Cutting Edge Optronics Inc. (St. Charles, MO) offers the UV Stiletto laser that provides high peak power pulses with typical optical pulsewidths of 25 nanoseconds at 1 kHz and 50 nanoseconds at 10 kHz. A 6.5-in. extension containing the nonlinear crystals and dichroic set is screwed onto the output of the laser head for 532 and 355 nm operation.




Polysulfone high-flow couplings

Lightweight high-flow couplings manufactured by Colder Products Co. (St. Paul, MN) are a cost-effective replacement for stainless-steel connectors and fittings. Applications include bioprocessing lines, cell culture bags, diagnostic device manufacturing, laboratory tubing connections, and kidney dialysis equipment.




Subminiature slide switch

Designed to reduce space and energy requirements, a microsubminiature slide switch from NKK Switches (Scottsdale, AZ) is less than 0.354 x 0.622 x 0.275 in. Insert-molded terminals and double-molded housings provide reliability and long life.




Double-lumen tubing

Measuring 5 mm OD with the smallest lumen at 0.45 mm OD, double-lumen tubing from Polygon Co. (Walkerton, IN) is constructed of continuous reinforced composite material. Initially developed for a laparoscopic surgical shielding system, the tubing is inherently insulative and has a dielectric strength of 800 V/mil.




Copyright ©1999 Medical Product Manufacturing News

Tubing-Processing Equipment



Tubing-Processing Equipment

Bump/taper tube system

Designed to precisely control the manufacture of bump/taper tubing, a bump/taper tube system offers precise speed regulation for exact output control. The system's extruder uses an integrally mounted single-bolt clamp ring assembly to permit quick changes of the die and screens. Its 12:1 double-reduction helical gearbox provides a large degree of flexibility in speed ranges. The operator interface uses a color touch screen Pentium computer running Windows NT 4.0 workstation. Davis-Standard Corp., 1 Extrusion Dr., Pawcatuck, CT 06379.


Servo rotary cutters

Two families of rotary-knife cutters are suitable for applications ranging from small-diameter medical tubing to rigid window and door profiles. The SCE-series cutters, which feature a velocity-controlled servomotor, and the new SCX series, featuring a position-controlled servomotor, provide high precision and speed. Both series are available with 2.25-, 3.25-, 4.25-, or as 5.25-in. bushing OD. They are available as stand-alone units or as combination puller/cutter models. Conair, 1 Conair Dr., Pittsburgh, PA 15202.


Tubing set coiler

An automatic coiling machine is used in the production and packaging of flexible tubing sets. The Mini-Winder coils medical tubing and other items that must be coiled before they are packaged. The unit allows significantly faster coiling than with conventional methods, and it reduces the chance of repetitive-motion injuries to hands and wrists. Electronic programming is used for precision operation. After a coil is complete, the mandrel (on which the product is wrapped) retracts, enabling the operator to slide the finished coil into a package without having to lift it. The unit allows many shapes of coils to be made, and coil sizes can be changed without tools. S-Y-M Products Company, LLC, P.O. Box 112160, Stamford, CT 06911.


Tubing cutter

A programmable cutting machine for medical-grade tubing features a system for solvent dispensing on the tube end and an uncoiling system with a tubing reel holder. ReadyCut is particularly suited to manufacturing medical tubing sets where cut-length precision, cut accuracy, and quality of solvent dispensing are of great importance. The system can be programmed in 1-mm increments to produce segments between 10 and 9999 mm, and it can process tubing ODs ranging from 3.0 to 9.9 mm. TechnoMed Inc., 59 Stiles Rd., Salem, NH 03079.


Tube expander

A pneumatic tube expander speeds the assembly of tubes and fittings while the tubing is open and on the expander. This feature is useful with tubing that has very fast memory-contraction rates, such as silicone. The Model 875B expander pneumatically expands 90° jaws with tubing assembled. The fitting is then inserted into the tubing and removed from the unit completely assembled. Teflon-coated jaws allow the tube with the inserted fitting to easily slide off the unit as a single assembly. The Teflon coating, as well as the jaw configuration, allows assemblies to be made without the use of Freon. Lakeview Equipment Inc., 2010 Lehigh Ave., Glenview, IL 60025.


Extrusion system

An alternate polymer tubing extrusion system can produce tubing that varies seamlessly from 100% polymer A to 100% polymer B along the length of the tube. This eliminates the secondary operation traditionally required to join tubes of different durometers or of entirely different polymers. It results in a much stronger transition and one which is completely seamless. Harrel Inc., 16 Fitch St., East Norwalk, CT 06855.


Heating ovens

Heat-shrink results can be duplicated more often using convection heating ovens than by using handheld heat guns. With the ovens, parts processed through the heat tunnel obtain a 360° even shrink fit as opposed to concentrated heat on only one side of the tubing. The Accu-Heat II heating ovens are portable, benchtop units and are electronically controlled for temperature and speed. Strategic Products Inc., 18 Marina Isles Blvd., Ste. 202, Indian Harbour Beach, FL 32937.


Tubing coiler

A tubing coiler automatically measures, cuts, and bands various diameters of flexible tubing. The machine pulls the tubing from a spool, wraps the tubing around two 1-in.-diam posts, retains the coil by heat sealing two ¾-in. tape strips around coils, and cuts the coiled assembly from the machine. The coils are then ready for the installation of connector fittings. The machine is capable of producing coils up to 172 in. long with a maximum of 12 wraps. Castle Engineering Company, Inc., 400 Corporate Cir., Unit N, Golden, CO 80401.


Catheter manufacturing equipment

Catheter manufacturing equipment allows operators to tip, neck down, and weld thermoplastics into finished catheters. Now CE marked, the PIRF systems meet the latest international standards for safety and emissions. The briefcase-sized systems provide fast, precise, and repeatable control of heat time, cool time, and insertion pressure. A proprietary process precisely controls mold temperature during heating. Thermoplastics such as polyethylene, fluoropolymers, PVC, polypropylene, and polyurethane weld and form easily using the equipment. SEBRA, 100 N. Tuscon Blvd., Tucson, AZ 85716.


Taper tube system

Control software for taper tube production comes standard on the Model TT.5 puller/cutter. The system uses streamlined functions and a faster servo update time to maximize productivity. It also features the Taper Wizard function, which eliminates the time-consuming task of manually entering all process values. The operator simply enters a few key values, and the Taper Wizard calculates and inputs all the necessary product dimensions to produce a symmetrical bubble tube. RDN Manufacturing Company, Inc., 160 Covington Dr., Bloomingdale, IL 60108.


Catheter manufacturing

A remote heat station is designed for tipping, welding, upsetting, bonding, and other related catheter manufacturing applications. The remote heat station allows the user to place the power supply separate from the tip-forming actuator. The unit features a low-friction pneumatic actuator with adjustable speed, stroke length, and tube-gripping pressure. Single- or double-tube configurations are available as a turnkey system. It includes the power supply, remote heat station, induction coil, cooling system tooling, and documented process parameters, and it requires only a 110/120-V 50/60-Hz power source. PlasticWeld Systems, 3690 Coomer Rd., Newfane, NY 14108.


Tubing cutting system

A tubing cutting system cuts a variety of sizes and shapes of plastic, elastomeric, and rubber tubing. Tubing sizes can be up to ½ in. diam, and four lengths of material can be cut at a time. The system is portable and includes a built-in counter, interchangeable tooling, and a fast material length adjustment device. AC&T Company, Inc., 7110-F W. Touhy Ave., Niles, IL 60714.

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Copyright ©1999 Medical Product Manufacturing News

CNC Grinder Produces Tools from Blank to Finished Product in One Complete Chucking



Machining

CNC Grinder Produces Tools from Blank to Finished Product in One Complete Chucking

Rotary burrs, end mills, and other tools made

A CNC TOOL automatically produces rotary burrs, end mills, router bits, and endodontic and surgical instruments for medical and dental applications. Extremely complex part geometries can be ground in a variety of small diameters.

The CNC 2005 grinder features a small footprint (68 x 52 x 66½ in.) and five separate axes, as well as a four-axis robot to pick and place blanks. Additional features include fast feed rates and cycle times and very tight tolerances for increased grinding accuracy.

According to the company, "The CNC 2005 is the only commercially available CNC grinder in the world that is designed for manufacturing small-diameter burrs or other types of tools complete from blank to finished tool in one chucking."

Secondary operations may be done at the same time with an optional piggyback drilling/milling spindle. The system contains four basic blocks: a grinding chamber, a robot, a work spindle, and a computer-controlled tool path. The variable-speed grinding spindle, which rotates between 4000 and 10,000 rpm, grinds the carbide blank in the cutting chamber. A spindle carrying up to three grinding wheels performs functions such as blank preparation and side fluting, as well as makes end cuts and chip breakers. A three-axis robot bearing two sets of jaws is used to pick and place individual burr blanks. The 300–500 blanks contained in each pallet are then ground according to specs generated on a PC design station.

For more information, contact Cutting Edge Technologies at 802/672-3399.

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Surface Treatment

A Thin-Film Metallization Process for Cardiac Catheters

Offers increased flexibility and durability

USING ION BEAM TECHNOLOGY to deposit a thin film of metal on polymeric substrates, a metallization process adds electrical conductivity to electrophysiology catheters. The SPI-METAL-EP process developed by Spire Corp. (Bedford, MA) will "assist medical device makers in fabricating more-flexible electrode arrays for cardiac catheterization and similar procedures," according to Ron Scharlack, vice president and general manager of the company. "The process also has potential applications for such implantable devices as small-joint orthopedic implants, urological stents, and tracheotomy tubes." Scharlack also points out that a recent National Heart, Lung, and Blood Institute–sponsored study has shown that the use of electrode catheters in electrophysiology can be an effective strategy in reducing the risk of arrhythmic death or cardiac arrest.

Conventional electrophysiology catheters contain wires and electrodes packed into the middle. The lack of flexibility resulting from this density of conductive materials makes it difficult to navigate the tortuous paths involved in, for example, reaching the heart. The metal coating process leaves a layer on the outside of the catheter from a few Å to 1 µm thick, increasing their flexibility while adding conductivity.

For more information, call Spire Corp. at 781/275-6000.

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Equipment

Handheld Operator Interface Features a Touch Screen

Gives the user several interface options

A HANDHELD OPERATOR INTERFACE features a 6.1 in., 640 x 480 VGA touch-screen display that can be oriented for either horizontal or vertical use. Standard features for the TouchLite from Two Technologies Inc. (Horsham, PA) include a 486 microprocessor running at 66 MHz, a fully configurable serial interface, and Microsoft Windows CE operating system. The device is equipped with two PCMCIA-compatible card slots, the first of which can accommodate version I and II, type I, II, or III PCMCIA cards. The second slot can hold 16MB flash EPROM and 8 MB DRAM storage cards, which can be supplied by the company. One of the two serial ports on the device is configurable for RS-232, RS-422, or RS-485, with the other configurable to just RS-232. Additionally, the unit contains front and rear facing IrDA ports, a USB port, and a 10baseT network connection. All of these provide a wide variety of interface options for the user.

The device measures 6.6 x 9.66 x 2.84 in. and is battery powered. SoundBlaster audio compatibility combined with built-in stereo speakers and a microphone allow it to be used for multimedia purposes. An optional magnetic smart card reader can be integrated into the device, making the unit card reader capable upon delivery. For custom applications, the company offers an attachment bus connector.

For more information, call Two Technologies Inc. at 215/441-5305.

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Internet

Weekly E-Mail Newsletter Offers Industry Updates

A weekly e-mail newsletter provides news and information of interest to medical device professionals. Sponsored by the Web site Medical Device Link, the free newsletter tracks notable industry trends and announces new additions to the site, including market research reports, news stories, annotated links, supplier directories, and job postings. The newsletter also gives details about upcoming industry trade shows and lets readers know whenever another Canon Communications publication—such as Medical Device & Diagnostic Industry, Medical Product Manufacturing News, IVD Technology, European Medical Device Manufacturer, Medical Electronics Manufacturing, and Pharmaceutical & Medical Packaging News—becomes available on-line. Readers will find a free subscription form at http://www.devicelink.com/register.

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Copyright ©1999 Medical Product Manufacturing News

Wound-Care Products, Plastics for Implants, and Mold-Building Services Introduced at MD&M East



Wound-Care Products, Plastics for Implants, and Mold-Building Services Introduced at MD&M East

Several companies introduced new products and services at the MD&M East 99 Conference and Exposition in New York City held May 25–27. Attendees were also able to see the products and services displayed by hundreds of exhibitors, as well as attend conference sessions on a variety of topics important to the medical device industry.

Products and Services Highlights

Avery Dennison (Painesville, OH) presented several new products including sterilization-indicator tapes, wound-care products featuring bidirectional stretch, and new formulas of polyurethane and PVC foams. The company noted that 80% of its products are custom made. Victrex (West Chester, PA) announced that it will be supplying PEEK for use in such long-term implants as hip replacements. The material can be processed in standard injection molding machines and doesn't need extensive secondary operations. Jamak Healthcare Technologies (Weatherford, TX) displayed its expertise in the development of silicone technology. The company said that its silicone products offer good formulation and process flexibility, combined with beneficial physical properties and long-term environmental stability. Smart Solutions (Beverly, MA) showed off its new SmarTeam-Works technical data management software. It is designed to give SolidWorks users the tools to create, edit, view, control, and annotate SolidWorks and office-type documents. SolidWorks users will also have the ability to perform advanced searches, maintain revisions in an intuitive manner, and quickly preview documents without actually opening the application that created them. SmarTeam-Works is suitable for desktop and workgroup-level applications, and it provides a direct migration to departmental and enterprise-level users as well.

Conference Highlights

The conference sessions gave attendees an opportunity to listen to experts discuss a variety of topics important to the medical device industry, such as quality systems, FDA submissions, effective design, medical validation, materials, and plastics processing. In the session "Thin-Walled Heat-Shrink Tubing in Medical Device Manufacturing," Mark Saab of Advanced Polymers Inc. (Salem, NH) explained the properties of polyester (PET) heat-shrink tubing, particularly its ability to create ultrathin walls, making it suitable for coating catheters. "PET can increase catheter stiffness two to three times with only a small increase in overall diameter," said Saab. By using different thicknesses of heat-shrink tubing along the length of the catheter, varying degrees of flexibility can be created for improved control of the device. This method eliminates the need for having to join sections of varying thicknesses. High dielectric strength and resistivity make PET a good choice for use as electrical insulation, he said. One application that Saab presented was a needle that was PET-coated along its body. In this way the electrical charge was prevented from touching the skin anywhere but at the tip of the needle.

In a session titled "Risk Analysis and Strategic Design Controls," Geetha Rao, PhD, explained that the goals of design control include establishing efficacy, minimizing safety hazards, complying with quality system regulations, and meeting business goals.

Rao, a managing engineer with Exponent Failure Analysis Associates (Menlo Park, CA), admitted that design control activities can be cumbersome and of questionable value if not well planned. However, she said that starting with a clear definition of the objectives and scope for the analysis can create a document that provides a framework for use throughout the life of a particular device. Failure mode effects analysis (FMEA) is the basis for such analysis. A combination of the usual FMEA brainstorming sessions as well as evaluations of the function and use of the device under normal and abnormal conditions help establish the basic framework of the FMEA. The approach outlined is best suited for devices whose designs are evolving or being modified.

Often, a bottom-up (inductive) approach is taken to establish failure scenarios for FMEAs by identifying initiating events and their relative impacts on safety or business. An example of an initiating event is component failure, which leads to loss of function. A top-down (deductive) approach can also be used to develop fault trees. Here, hazards are identified first, then their potential causes. While top-down approaches are easier to establish and are often recommended by regulatory agencies as a good starting point, Rao says that they are less useful in the long run than FMEAs. Using a top-down approach increases the likelihood that the analysis will be insufficient in scope. This approach also does not account for the probability of any of these events.

Rao suggests using a mixture of top-down and bottom-up approaches, using the generic failure modes as starting points. TÜV Product Service (New Brighton, MN) recommends defining these as "the first point in the causal chain at which the patient is affected." Rao said that a more generalized guideline is defining a failure mode as a potentially adverse experience after the device is handed off, thus potentially involving a physician, surgeon, or hospital, among others.

Although it is impossible to eliminate all unexpected events that can cause product failure, an effective analysis can help minimize their frequency and consequences. The documentation also helps improve the device as each issue is identified and corrected, whether through design, manufacturing, or use.

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Business and Acquisition News

Plexus Corp. (Neehah, WI) has opened a new facility in Louisville, CO. The 14,000-sq-ft facility is designed to house up to 60 engineers. It will expand upon the company's engineering services, which include analog, digital, PCB, firmware, and mechanical design. Chemfab Corp. (Merrimack, NH) has introduced its Engineered Elastomer Products Division. It will focus on the design and manufacture of finished products based on high-performance engineered elastomer materials. NuSil Technology (Carpinteria, CA) has created a new subsidiary, NuSil Technology Ltd., with a manufacturing, development laboratory, and technical support facility in Arklow, Ireland. LNP Engineered Plastics (Exton, PA) has announced the completion of a warehouse expansion at its plant in Thorndale, PA. The 23,000-sq-ft expansion enables LNP to provide faster turnaround. Servomex (Norwood, MA) has announced the formation of a new company, Servomex Transducers Ltd., to further develop its gas transducer technology. The new company will design and manufacture the Servomex range of gas transducers, which are marketed to industrial and medical OEMs and are also the key components of the Servomex range of process and environmental gas analyzers. The Plastics Technology Group of NewAge Industries Inc. (Willow Grove, PA) has announced the expansion of its silicone tubing and hose extrusion operation to include platinum-cured products. The facility now produces all of the company's stock silicone products, as well as handling the various special items that customers request. Prent Corp. (Janesville, WI), a producer of thin-sheet thermoformed products for the medical and electronics industries, has expanded its global operations with new facilities in Malaysia and Costa Rica. The Tech Group Inc. (Scottsdale, AZ) has acquired Vollrath Group Inc. (Sheboygan, WI). Vollrath is a leading supplier of plastic utensils and kit products for the healthcare market. Fluoroware Inc. (Chaska, MN) has announced the European launch of its Cynergy product line. The Cynergy sanitary components are nonmetallic fluid-handling systems capable of withstanding SIP/CIP cycles. Lasertechnics Marking Corp. (Albuquerque) has been acquired by Amphion Capital, a New York City investment capital firm. Lasertechnics provides laser coding systems worldwide. Moll Industries Inc. ( Knoxville, TN), a global supplier of injection-molded plastic components and assemblies, has purchased three U.S. and Canadian facilities from Compression Engineering Inc. Compression Engineering specializes in industrial design, product development, and engineering. Acutek has relocated its European sales office to Brussels, Belgium. Headquartered in Inglewood, CA, Acutek provides pressure-sensitive converting services. Ismeca USA Inc. is moving its North American headquarters to a larger facility located in nearby Vista, CA. The new facility will have the capacity to accommodate additional growth for at least five years by adding 25,000 sq ft. Ciba Specialty Chemicals, Performance Polymers Div., (East Lansing, MI) and Z Corp. (Somerville, MA) have announced an R&D partnership. They will develop new materials for the rapid generation of 3-D models and prototypes. Entela Inc. (Grand Rapids, MI) has acquired Integrity Design and Test Services Inc. (Littleton, MA). Integrity provides product safety and EMC testing to worldwide regulatory standards. Griffith Micro Science (Oak Brook, IL), a provider of sterilization services, has agreed to acquisition by Ion Beam Applications of Belgium. Ion Beam Applications designs and produces particle accelerators for medicine and industry. Creative Imprints Inc. (Norton, MA) has moved to a new, larger facility. The company specializes in providing complex contract printing services with medical-grade inks. Nypro of Puerto Rico has expanded its Technology Center. It now has the latest machinery used for rapid mold making, as well as advanced research and development capabilities. SurModics Inc. (Eden Prairie, MN) has won the 1999 Minnesota Technology Company award from Minnesota Technology Inc. SurModics was chosen due to the market success of its PhotoLink surface-modification technology. Cicoil (Los Angeles) has developed a new manufacturing process for silicon-rubber-encapsulated flat cable. The new method uses a proprietary continuous process that allows flat silicon cables to be produced with virtually any number of conductors in any length.

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Copyright ©1999 Medical Product Manufacturing News

Cutting-Edge Technology Enables the Deaf to Hear



Cutting-Edge Technology Enables the Deaf to Hear

Karim Marouf, Managing Editor

Many medical OEMs push the boundaries of technology to develop devices that restore functions or abilities. The suppliers that partner with them are challenged to pioneer their own technologies in order to provide solutions for the device manufacturers' needs. But the rewards for both companies are many.

Not only do suppliers and manufacturers get the satisfaction of collaborating to make a product that improves people's lives, but they can also apply the new technology to other devices in medical and other industries. Such a mutually beneficial relationship occurred during the development of the Clarion cochlear implant, built by Advanced Bionics Corp. of Sylmar, CA, with the help of its supplier, AVX Corp. of Myrtle Beach, SC.

Some deaf people benefit little, if at all, from hearing aids, and the Clarion cochlear implant was designed specifically to help them. Unlike a traditional hearing aid, the device actually bypasses much of the auditory system and delivers electrical stimulation directly to the hearing nerves of the inner ear.

The "Bionic Ear"

A remote speech processor, connected to a quarter-sized headpiece, converts incoming sound into electronic codes. The headpiece receives the sound information from the processor and transmits it via radio waves to a cochlear implant. The implant is a small microcircuit that is placed under the skin and attached to the skull.

An electrode array of very thin wires extends from this implant to the inner ear through a hole drilled into the skull. The array inserts directly into the inner ear and provides the interface between the device's electronics and the human nervous system. Electrical current excites the inner ear's nerve fibers, and these in turn deliver the signals to the brain, where they are interpreted as sound.

AVX Corp. developed the miniature capacitors for the Clarion system's headpiece.

The technology achieves impressive results. "I'm totally deaf in both ears," says implant user Doug Lynch, manager of marketing communications for Advanced Bionics. "I'm representative of an individual that you can strap as many hearing aids on as you want without any benefit to my hearing. But with the implant I'm able to hear normally."

Although the principles of this technology have been around since the 1970s, the technology has progressed dramatically in just the past five years. Advances in electronics miniaturization were the primary catalyst for Advanced Bionics.

For help in achieving the necessary miniaturization, Advanced Bionics went to its supplier, AVX Corp., a manufacturer of a variety of passive and electromechanical components such as resistors, ultraminiature fuses, and connectors. AVX developed the miniaturized TAC tantalum capacitor to fit into the headpiece unit.

The temperature and voltage stability of tantalum enabled the designers to achieve miniaturization without compromising performance. But AVX had to develop new methods of making the capacitor. Craig Hunter of AVX explains: "The normal method of making a tantalum capacitor wouldn't have worked because the capacitor would've been too big. A completely new production method was developed. It involves a new termination—how it's connected to the PCB." The capacitor is 10 times more powerful than a traditional tantalum capacitor of its size. It measures only 0.06 x 0.03 in.

A Challenge for the Future

"I'm fascinated by the Clarion device, as much from the perspective of someone who uses it as well as from someone who's just interested in seeing the incredible things being done in biotechnology," says Lynch.

"From our side, it's great when you cannot just push the boundaries, but in the end can achieve something substantial," says Hunter. "You're not just making a smaller cell phone or something like that. You're enabling a deaf person to hear. That's incredibly rewarding, and something everyone at our company can be proud of."

The Clarion system delivers electrical stimulation directly to the hearing nerves of the inner ear.

The Clarion cochlear implant was approved by FDA for children in 1997 and for adults in 1998, and since then thousands of people have had the device implanted. A possible future improvement may involve having the headpiece also implanted. This will only be possible with further miniaturization of digital processing chips and other components, and that will require a leap in technology.

Advanced Bionics won't shy away from taking on such challenges in the future. Its suppliers, including AVX, continue to offer support by overcoming the technological barriers needed to achieve success.

The rewards will be far-reaching. Hunter concludes: "Medical companies like Advanced Bionics create developments so revolutionary that they force us to work hard to improve our own technology and to really push the boundaries. In the end we doubly benefit since the next logical step after developing a solution to fit their needs is to see in what other industries our new technology can be applied."

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Copyright ©1999 Medical Product Manufacturing News

Standard and custom shielding



EMI/RFI Shielding

Standard and custom shielding

A company offers a range of shielding products for doors, panels, enclosures, and cabinets of medical electronics equipment. Products include wire mesh shielding with an optional elastomer core, gasket materials, fan vents, filters, and honeycomb vents. BeCu strips are offered in low-profile designs as well as with hook-on, stick-on, clip-on, and track mounting. Tech-Etch Inc., 45 Aldrin Rd., Plymouth, MA 02360.




Shielding gasket

An EMI/RFI shielding gasket features two symmetrical contact bulbs. One bulb has a highly conductive coextruded outer layer for EMI/RFI shielding, and the other bulb acts as a dedicated environmental seal to protect electronic enclosures from moisture and contaminants. The gasket provides shielding effectiveness of >100 dB up to 1 GHz. Vanguard Products Corp., 87 Newtown Rd., Danbury, CT 06810.




Circuit board shielding

A company offers circuit board shielding with a patented removable cover design to protect sensitive components from noise while providing access for adjustments and repairs. The company's line of rugged CBS-style shielding cans includes a 20-S surface-mount version and a versatile CBS2 dual-sided shielding enclosure. Manufacturing services and custom design are also available. Leader Tech, 14100 McCormick Dr., Tampa, FL 33626.




Custom switch assembly

A maker of custom control panels, membrane switches, and display filters and lenses can provide shielding for ESD, EMI, and RFI. A custom switch assembly combines plastic extrusions, a membrane switch, and mechanical actuators. The mechanical actuators placed over the membrane switch offer the tactile response of mechanical switches while increasing the reliability and seal of the membrane switch. Unique contact and circuit line configurations can accommodate special schematic needs such as multipole switching. Silver Cloud Manufacturing, 525 Orange St., Millville, NJ 08332-5002.




Silicone elastomer rings

O-seals made of electrically conductive silicone elastomer are available in round or rectangular cross sections. In addition to providing high electrical conductivity, the O-seals offer effective shielding and moisture and pressure sealing. Designed for static applications in which the sealed surfaces do not move in relation to each other, the O-seals are typically used for sealing connectors, jam nuts, waveguide flanges, and caps. Tecknit, 129 Dermody St., Cranford, NJ 07016.




Shielded shrink tubing

Shrink tubing is designed specifically for EMI control and physical protection of wires and cables. Shrink-N-Shield tubing consists of an outer jacketing made of flame-retardant polyolefin shrink tubing lined with a metallized fabric shield. Available in ODs ranging from 1/8 to 1 in., the tubing easily slides onto wire bundles and can then be shrunk to a tight protective fit using a standard industrial heat gun. Shrink rates are 50% radially and 10% or less longitudinally. The Zippertubing Co., P.O. Box 61129, Los Angeles, CA 90061.




Air-vent honeycomb filters

Designed to provide consistent shielding while allowing cooling air to penetrate an equipment cabinet, shielded air-vent honeycomb filters are available with three levels of shielding. The Econo-Cell provides shielding effectiveness levels of 90 dB at 1 GHz , while the Spira-Cell double-panel configuration and the Brass-Cell single-panel design offer shielding effectiveness of 140 dB at 1 GHz. Spira Manufacturing Corp., 12721 Saticoy St. S., North Hollywood, CA 91605.




Gel rope gaskets

Gaskets made from wire mesh impregnated with cured silicone gel provide EMI shielding, electrical grounding, and environmental sealing. The silicone gel exhibits displacement characteristics under pressure, and its ability to adhere to a surface on contact enables it to form an effective moisture and pressure barrier. The dBseal EMI gel rope gaskets provide a cost-effective alternative to using two-piece rubber and metal mesh gaskets or one-piece metal-filled conductive elastomers. The gaskets incorporate a circular compressed wire mesh rope made from a low-cost copper-nickel alloy. Raychem Corp., 300 Constitution Dr., Menlo Park, CA 94025-1164.




Wide release liner

Designed to reduce assembly time, a wide release liner attaches to taped EMI shielding gaskets. The oversized release liner makes pick-and-place manufacturing possible and facilitates fast gasket installation. EMI shielding gaskets can be kiss-cut to 0.118 in. with the wide release liner. The manufacturer's EMI shielding products are made from highly conductive materials, resilient urethane foam, structural laminates, and corrosion-resistant coatings. Schlegal Systems, 1555 Jefferson Rd., Rochester, NY 14623.




Thin-film deposition products

A company specializes in thin-film deposition through sputtering and plasma technologies. The company provides EMI/RFI shielding in rolls of flexible substrates made from polyester, polyimide, or woven fabrics. Conductive coatings are made from chromium, copper, gold, inconel, nichrome, nickel, palladium, silver, and indium tin oxide. Techni-Met Inc., 300 Lamberton Rd., Windsor, CT 06095.




RFI shielding structures

A company offers patented RFI shielding materials for biomedical instrumentation applications. MSD-4 is available in a variety of shapes and sizes for wall-to-wall shielding or as discrete wrap-around components to envelop sources of RFI emissions within a digital system. The shielding also provides system protection in attentuating radiated EMI between the systems that originate the interference and systems susceptible to such interference. Shielding systems can be applied adhesively or mechanically using screws or solder. Topflight Corp., P.O. Box 2847, York, PA 17405-2847




Shielded windows

EMI shielded windows feature a proprietary mesh system that provides good optical performance and eliminates text distortion on CRT displays. EmiClare GP 70 windows offer a 12% improvement in light transmission compared to conventional laminated EMI shielding windows, according to the manufacturer. A minimum of 55 dB of shielding effectiveness is provided at 1 GHz. Front surfaces are treated with a nonglare hard coat for scratch and chemical resistance, and rear surfaces have a clear hard coat. Chomerics, Div. Of Parker Hannifin, 77 Dragon Ct., Woburn, MA 01888.




Form-in-place gaskets

A company has expanded its line of form-in-place EMI gaskets to include single-component silicone-based compounds that can reduce package dimensions and provide additional packaging space for board-level components. ElectroForm Series 8558 compounds reduce raw material, labor, and assembly requirements for shielding and grounding metal and plastic housings, substrates, and enclosure panels. The compounds are filled with proprietary conductive particles and provide shielding effectiveness of >120 dB at 1 GHz. Because the compounds do not require mixing, they can reduce production cycles and waste. Instrument Specialties Company, Inc., Shielding Way, Delaware Water Gap, PA 18327-0136.




RFI ferrite

A high-impedance RFI ferrite features a multihole design that permits multiple passes of the same cable in a serpentine manner. High-frequency interference is absorbed by the ferrite core, and lower-frequency data signals pass unimpeded. Three styles accommodate two or three cable diameter loops up to 0.365 in. diam each, or multiple cables may be inserted for a unitized bundle package. FerriShield Inc., 350 Fifth Ave., Ste. 7310, New York, NY 10118-7591.



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Copyright ©1999 Medical Product Manufacturing News

Prescription For The Future: Drug-Delivery Product Embodies Development Trends

Medical Device & Diagnostic Industry Magazine
MDDI Article Index

An MD&DI July 1999 Column

Drawing on the latest interdisciplinary research, a noted scientist prepares to produce a revolutionary controlled-release device. Will long lines at the drugstore be a thing of the past?

A major provision of the Administration's recently unveiled plan for Medicare reform is a proposal to offer prescription drug coverage to nearly 40 million elderly and disabled beneficiaries. President Clinton is confident that he can patch up Social Security and then find "enough funding left over" to help pay for the potions and pills.

Perhaps the President should check first with Robert Langer on the cost estimate. Because, if a project envisioned by MIT's celebrated Germeshausen Professor of Chemical and Biomedical Engineering actually materializes, the government could be on the hook not for 40 million prescriptions, but for 40 million drugstores!

In a keynote address delivered in San Francisco at the recent Biomaterials of the Future conference organized by Medical Data International (Santa Ana, CA), Langer discoursed on a range of current and near-term research developments in biomaterials, drug delivery, and tissue engineering. Prominent among these was what he called the "pharmacy on a chip." Together with colleagues in his laboratory, Langer designed a dime-sized, implantable drug-delivery device etched from a solid-state silicon microchip. The prototype chip incorporated 34 microreservoirs filled with saline; a commercialized version could house, say, 1000 reservoirs, each containing a dose of medication, hormone, or other chemical preprogrammed for release in concert or at different times over periods up to several months. The tiny wells are individually sealed with extremely thin anode membrane lids of gold, which can be made to dissolve upon application of an electrical pulse, releasing the dose.

While several aspects of this project are extraordinary, they are at the same time paradigmatic of wider trends in the device industry. The design brings together advanced work in a number of intensely active disciplines: microprocessor systems, biocompatible and biodegradable polymer technology, micromachining and microfabrication, biosensors, surface analysis. The incorporation of active agents in a biomaterial structure points up the increasing prevalence of various types of "combination" products—from other controlled-release matrices to encapsulated cell lines to bioactive coatings. And the ability of the chip to be externally programmed or reprogrammed depending on the condition or needs of the patient reflects evolving capabilities in interactive and remote power sources, control and monitoring mechanisms, and data gathering and transmission modalities.

The device is also remarkable for the scope of the problem it addresses and the potential ramifications should it or a similar product come to market. Langer stated that adverse drug effects from improperly used prescription medications—by the feeble, the misinformed, the unlucky—account for 15% of all hospital admissions and 100,000 deaths each year, at an annual cost estimated at $136 billion (greater than that incurred from heart disease!). For patients, ensuring drug compliance through an implantable pharmacopoeia could influence everything from subsequent treatment regimens to dependence on skilled caregivers to transportation requirements.

Langer and team have formed a company to explore commercial development of the pharmacy chip and other drug-delivery technologies—for example, inhalation research investigating aerosol particle structure and size. This illustrates another prevalent trend: that many academics are going into business on the side. Perhaps the firm's first chip will be a startup business model: tinfoil lids and wells filled with caffeine and midnight oil.

Jon Katz

jon.katz@cancom.com


Copyright ©1999 Medical Device & Diagnostic Industry

FDA Action Plan to Improve Regulation of Biologic Devices

Medical Device & Diagnostic Industry Magazine
MDDI Article Index

An MD&DI July 1999 Column

WASHINGTON WRAP-UP

CBER will harmonize its policies with CDRH.

James G. Dickinson


  • FDA's Topside Back the Way It Was
  • FDA Approves TransScan's Breast Imaging Device
  • FDA's Y2K Compliance Policy Guide
  • Phillips Medical Recalls X-Ray Devices
  • FDA Updates List of Reviewers

FDA's Center for Biologics Evaluation and Research (CBER) in April announced a major "action plan" by which it intends to minimize or eliminate inconsistencies between itself and CDRH in the handling of devices that are also biologics.

A driving force for this is the FDA Modernization Act of 1997, which directed the agency to improve its relationships with regulated industries. Other factors motivating CBER are input it has received from its external constituencies and a desire to compare more favorably with CDRH, which is producing impressive results from its ongoing reengineering initiatives.

The action plan calls for implementation of a "transparent process" for consistently applying regulatory and administrative requirements to the review, inspection, and compliance follow-up of biologic devices. It sets a deadline of September 30 for identifying biologics that should have device inspection methods (e.g., tines, prefilled syringes, and injectors) and for determining if any deviations from CDRH policies can be justified. By October 31, the Team Biologics Operation Group is to implement agreed-upon recommendations and any necessary training of both FDA and state inspectors is to begin by April 1, 2000.

The action plan also demands improved communications, both between the center and industry and between CDRH and CBER. Stakeholder meetings were held in June to get outside input on achieving this objective, and an FDA assessment of progress made is slated for next April.

CBER's action plan also targets device-review performance within the biologics center, acknowledging that there have been "problems" in processing applications by their legal deadlines. The intent is to identify and implement workload-reduction measures such as guidance development and to harmonize the center's policies with CDRH by October 1.

They say there's no turning back the clock, but in a real sense that's what FDA commissioner Jane Henney is doing in her reorganization of the commissioner's office, which was announced to agency staff in April. Almost everything that David Kessler did in the office is now being undone, and the day-to-day operational power of the agency is being returned wherever possible to the various program centers and to the field organization. There is even a subtle restoration of the policy-guiding role of the Office of Chief Counsel, the downgrading of which is claimed by most former FDA chief counsels to be a factor in the recent, unprecedented run of courtroom losses suffered by the agency.

In addition, one Kessler innovation, the Office of Special Investigations, headed by Jack Mitchell, is being abolished. This office caused a good deal of managerial paranoia because its function was never clearly communicated; Kessler used it as a listening post for a time, trying to gather intelligence about employee perceptions of possible wrongs committed by other employees, but soon grew tired of its "interference" and stopped heeding its advice.

In the April 22 memo to affected employees, Henney said she approached the reorganization with four goals:


  • To create an Office of the Commissioner in which the principal focus is on providing leadership in building effective, two-way communication between the agency and its stakeholders, among whom she included "patients, consumers, Congress, the Administration, agency employees, the regulated industry, health care professionals, and other scientific advisors."
  • To implement FDA goals and develop policy with primary input from the center directors and the associate commissioner for regulatory affairs, "and with legal advice from the Chief Counsel."
  • To streamline the Office of the Commissioner to make the overall agency more effective and efficient, with roles and responsibilities clearly delineated.
  • To retain in the Office of the Commissioner only those staff functions that cannot be reasonably and more effectively performed in the centers or the Office of Regulatory Affairs.

These goals come straight out of Henney's preappointment discussions on Capitol Hill and her confirmation hearing. They were parlayed to key lawmakers before being announced inside FDA, and reportedly met an enthusiastic response: "This is exactly what we hoped you'd do," one legislator reportedly said. In that one comment, Henney probably divined that there existed no great support for the Kessler legacy.

The most noticeable impact of the reorganization—which has just taken effect following negotiation with the FDA employees union and some budgetary reprogramming from Congress—will likely be the ascendancy of newly titled senior associate commissioner Linda Suydam, who has been given responsibility for coordinating all activities within the Office of the Commissioner. Suydam will also directly supervise the following entities: the Chief Mediator and Ombudsman staff, Office of the Executive Secretariat, Office of Public Affairs, Office of Orphan Products Development, the Internal Affairs staff, the Advisory Committee Oversight staff, and the Office of Tobacco Programs. During the Kessler years, Suydam played a key role in CDRH management.

Henney assumes direct line-reporting contact for all of the center directors, who previously reported through deputy commissioner Michael Friedman (who has no specific responsibilities in the reorganization other than being Henney's second-in-command). Newly appointed associate commissioner for regulatory affairs Dennis Baker, who heads field enforcement, will also report directly to Henney.

Additional personnel moves include the appointment of acting deputy commissioner for policy William Hubbard to the post of senior associate commissioner for legislation, policy, and program planning, where he will oversee the offices of policy coordination, legislative affairs, and planning and evaluation. Deputy commissioner for external affairs Sharon Smith Holston will have her title changed to deputy commissioner for international and constituent relations, and deputy commissioner for management and systems Robert Byrd will retain his present responsibilities. Holston's and Byrd's office titles will be eliminated when they leave those positions, which will be renamed "associate commissioners" instead of "deputy commissioners."

One effect of the reorganization will be to relocate some 130 positions out of the Office of the Commissioner—90 of them into the centers and the remainder elsewhere in the agency.

In April, FDA approved a new imaging device by TransScan Medical Inc. (Ramsey, NJ) that will help radiologists determine, when mammogram results are ambiguous, whether a woman should be evaluated further. The T-Scan 2000 "has the potential to reduce the number of negative biopsies," FDA says, "and increase the identification of women who should be referred for early biopsy."

In a talk paper, FDA said the T-Scan uses a handheld scan probe placed on the breast to evaluate certain suspicious areas detected on the mammogram. The probe is connected to a computer, which displays an image of the involved areas of the breast. The T-Scan images are based on differences in the electrical impedance between malignant tumor tissue and the surrounding normal tissues. The device measures impedance by passing a small electrical signal through the body and displaying on a computer the result from sensors in the probe contacting the breast. The computer image contains bright spots where the impedance values are consistent with a possible malignancy.

As a condition of approval, TransScan Medical is being required to conduct a postmarket study on the effects of hormonal changes during the menstrual cycle on the device's ability to detect and distinguish among breast abnormalities.

A just-updated, three-page FDA compliance policy guide (CPG160-800) on year 2000 (Y2K) computer compliance gives agency field investigators detailed instructions on what enforcement actions should be taken when Y2K noncompliance is encountered during inspections. Mere noncompliance is not to be listed on the FDA-483, the guide says, but "observations regarding specific process or product deficiencies related to the Y2K problem should be listed."

Likewise, for medical devices, if a firm initiates a correction or removal to address a Y2K problem and that action is intended to reduce a risk to health, "then the firm must report their action to FDA . . . regardless of whether or not there has been a malfunction related to Y2K," according to the guide. The document is available at http://www.fda.gov/ora/compliance_ref/cpg/cpggenl/cpg160-800.html.

Phillips Medical Systems of Shelton, CT, conducted a Class II recall (indicating serious but reversible health consequences) of 1086 Integris x-ray controls and generators on April 6 because they were found to be defective under their FDA performance standard. According to the April 21 FDA Weekly Enforcement Report, the defect occurs when the system is driven to a maximum entrance exposure rate and the source-to-image-receptor distance is reduced while exposures continue to be made. In this manner of operation, the output may exceed 10 rd/min because the software will not update the output until the exposure control is released.

FDA has posted its newest roster of accredited third parties authorized to review selected 510(k)s that would otherwise be submitted to the agency for review. Devices eligible for third-party review are limited to those listed on FDA's Web site.

The latest list of accredited reviewers, with contact information and device panel categories, is as follows:


  • Applied Science & Technology Associates (Cedar Grove, NJ; Herbert E. Spiegel, phone/fax 973/857-0062), clinical chemistry, clinical toxicology, immunology.
  • BSI—British Standards Institution (London; Perter J.C. Walker, phone +44 01 81 996 6442, fax +44 01 81 996 6452), anesthesiology, clinical chemistry, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, neurology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery, clinical toxicology.
  • California Department of Health Services, Food and Drug Branch (Sacramento, CA; James M. Barquest, phone 916/445-2263, fax 916/322-6326), clinical chemistry, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, clinical toxicology, neurology.
  • Center for Measurement Standards of Industrial Technology Research Institute (Hsinchu, China; Chang Hsu, phone 886 35 732201, fax 886 35 716231), cardiovascular, general hospital, neurology.
  • Cheiroon BV (Wageningen, The Netherlands; Anjo Strik, phone/fax: +31 317 411 835), clinical chemistry, hematology, immunology, microbiology, neurology, obstetrics/gynecology, orthopedic, radiology, general and plastic surgery, clinical toxicology.
  • CITECH (Plymouth Meeting, PA; Robert Mosenkis, phone 610/825-6700, fax 610/834-1275), anesthesiology, clinical chemistry, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, neurology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery, clinical toxicology.
  • Entela Inc. (Grand Rapids, MI; Tim Hubbard, phone 616/248-9646, fax 616/ 248-0591), anesthesiology, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, neurology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery, clinical toxicology.
  • Intertek Testing Services (Boxborough, MA; Donald Sherratt, phone 978/263-2662, fax 978/264-0393), cardiovascular, dental, gastroenterology/urology, general hospital, urology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery.
  • NIOM—Scandinavian Institute of Dental Materials (Haslum, Norway; Arne Hensten Pettersen, phone +47 67 51 2200, fax +47 67 59 1530), dental.
  • N.V. Kema (Arnhem, The Netherlands; P. N. Ruys, phone +31 26 356 3939, fax +31 26 351 6708), anesthesiology, cardiovascular, dental, gastroenterology/urology, general hospital, neurology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery.
  • TÜV Product Service (New Brighton, MN; Carole Stamp, phone 651/638-0294, fax 651/638-0295), anesthesiology, clinical chemistry, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, neurology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery, clinical toxicology).
  • TÜV Rheinland of North America Inc. (Newton, CT; Reiner Krumme, phone 203/426-0888, fax 203/270-8883), anesthesiology, clinical chemistry, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, neurology, obstetrics/ gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery, clinical toxicology.
  • Underwriters Laboratories (Northbrook, IL; George Kreiner, phone 847/272-8800, ext. 43004, fax 847/509-6213), anesthesiology, clinical chemistry, cardiovascular, dental, gastroenterology/urology, hematology, general hospital, immunology, microbiology, neurology, obstetrics/gynecology, ophthalmology, orthopedic, physical medicine, radiology, general and plastic surgery, clinical toxicology.

Copyright ©1999 Medical Device & Diagnostic Industry

Implantable Chips and Advanced Materials Stimulate Research Efforts to Restore Sight

Medical Device & Diagnostic Industry Magazine
MDDI Article Index

An MD&DI July 1999 Column

Current efforts to develop a functional retinal implant are focused on returning useful vision to patients with retinitis pigmentosa and age-related macular degeneration.

Current research in bio-optics and bioelectronics could one day help restore a degree of vision to people afflicted by most common forms of blindness. Several engineering approaches are being explored to develop neuroprosthetic devices that can emulate normal vision to some degree. Much of this research involves the application of an innovative combination of technologies that have undergone remarkable progress in recent years, including advanced microprocessor systems, smaller and more-sensitive sensors, and new materials.

View of the fundus, showing the retina in which an artificial silicon retina has been implanted.

The retina is essentially tissue composed of several different cell types arranged in layers at the back of the eye. One layer contains the photoreceptors, the rods and cones, which take light signals that enter the front of the eye and convert them to neural signals. The most common retinal diseases, including retinitis pigmentosa (RP) and age-related macular degeneration (AMD), occur when the function of the photoreceptor cells is lost, becoming insensitive to light, while the rest of the cell types in the retina remain relatively intact. Because the function of photoreceptors is to convert light energy into neuroelectric energy, most of the current research is focused on artificially reproducing this activity to restore useful vision to the more than 10 million persons afflicted with RP or AMD worldwide.

"EYE OF NEWT" ADDS MAGIC TO PROTOTYPE ARTIFICIAL RETINA

In 1997, a group of researchers from the Institute of Physical and Chemical Research (RIKEN; Nagoya, Japan) and Nagoya University succeeded in developing an artificial retina design that combines semiconductor components with living nerve cells from newts. The novel device is based on use of a layer of cultured newt retinal cells positioned on a substrate of photoconductor elements. Light hitting the photoconductor substrate generates electrical signals that subsequently stimulate the nerve cells, the researchers indicate.

The researchers conducted computer simulations indicating that the photoconducters transmit signals to the retinal cells using a current of 0.1 to 1.0 mA. While the human retina relies on approximately 800,000 living cells that function as photodetectors, the prototype device uses only 64 silicon photodetectors. The research team noted, however, that the initial success of the prototype verified the potential of the device as a vision aid.

The group has built upon the information generated during its earlier success to develop a hybrid artificial retina that combines neural transplantation of human eye cells with a semiconductor device incorporating silicon photodetectors. The researchers recently noted that, using micromachining technology, a prototype microelectrode array was created for extracellular stimulation of nervous systems. The array consists of nine-channel bipolar electrodes, arranged in nine anode/cathode pairs in a 3 x 3 lattice. Each electrode has a 20 x 20-µm square shape. The distance between each pair is approximately 320 µm to reduce cross talk between pairs. In its next study, the group plans to evaluate the performance of the array during in vivo and in vitro extracellular stimulation experiments.

LASER POWERS IMPLANTED CHIP

In a separate project, a partial artificial retina is being developed by the Retinal Implant Project, a joint research effort being conducted by scientists from the Massachusetts Eye and Ear Infirmary (Boston), the Massachusetts Institute of Technology (MIT; Cambridge, MA), and Harvard Medical School (Boston). The researchers have designed and tested a prototype incorporating an "ultrathin microchip that can be surgically implanted on the retina," according to the MIT researchers.

Surgically implanted under the retinal tissue, the artificial retina generates signals similar to those produced by the natural photoreceptor layer of the eye.

"The microchip serves to bypass the defective rods and cones by stimulating healthy ganglion cells directly with tiny electrical currents," the researchers explain. An 820-nm infrared external laser, along with a tiny camera, is mounted onto a pair of eyeglasses that capture visual images using the charge-coupled device (CCD). The images are converted to digital signals and transmitted by laser to the implanted chip. The chip then transmits the electrical impulses to the brain "by stimulating remaining healthy retinal ganglion cells using an array of electrodes surgically implanted on the retina," says John Wyatt, PhD, of the MIT department of electrical engineering and computer science. "The team has carried out electrical threshold measurements on nearly a hundred rabbit retinal ganglion cells to accurately determine the minimum amount of current and power needed for retinal stimulation. In addition, a number of short-term in vivo electrical stimulation experiments were performed, recording responses in the visual cortex to stimulation of small areas of the retina. Also, a large number of surgical experiments on laboratory animals were performed to develop improved techniques for implanting the device on delicate retinal tissue."

Although the laser has not been tested with the camera yet, the researchers recently completed a one-year experimental study of the biocompatibility of several implant materials, including silicone elastomer and hydrogels. "The next short-term objective is to refine the method for applying the silicone coating to the implant [because] even the smallest leak of salt from the eye into the implant would destroy function of the microchip," Wyatt explains.

The ASR is powered solely by incident light and requires no external wires or batteries.

The goal of the research is to verify the brain's response to the implant, "first acutely, and then over progressively longer implantation periods," Wyatt says, adding, "This will involve repeated retest and redesign to reduce retinal trauma." Once this is accomplished, the researchers plan to "develop strategies to make the electrical stimulation as selective as possible for the desired cell types; design and build a second-generation implant capable of driving each of the stimulating electrodes separately; restore vision to animals that have been blinded by retinitis pigmentosa; and, finally, [start trials] with blind human volunteers."

BIOCOMPATIBILITY POSES AN ADDITIONAL CHALLENGE

Research led by Wentai Liu, PhD, a professor of electrical engineering at North Carolina State University (NCSU; Raleigh), and funded in part by a National Science Foundation grant is investigating the use of a prosthesis incorporating a laser-powered silicon bipolar contact artificial retina chip. The research is being conducted jointly with Mark S. Humayun, MD, PhD, and Eugene DeJuan, MD, of The Wilmer Ophthalmologic Institute at Johns Hopkins University (Baltimore).

"The major challenge is to have a miniaturized prosthetic device that is hermetically sealed, biocompatible, low power, and implantable," says Liu. "A complete prototype device is not finished, but major components have been done and tested." Liu also indicates that clinical testing of the prosthesis concept has been performed on 15 subjects to date—13 patients with end-stage RP and 2 suffering from AMD.

The prosthetic device comprises two subsystems. The first is outside of the eye to acquire, code, and transmit an image. The second, implanted within the eye, is designed to receive and decode image data, and then apply an appropriate stimulation pattern to the retina. The external portion of the system consists of a minicamera, video-capture circuit, and power and video-data transmission circuit mounted onto a special pair of glasses. Electrical power is transmitted wirelessly to the implanted chip using a two-wire coil configuration that functions similarly to a transformer.

The retinal chip within the eye has been designed to stimulate the retina in such a way as to form a 10 x 10-pixel image. According to the researchers, an improved version of this chip should be capable of sending operating-status data back to the glasses for monitoring. The chip specifications have been based on preliminary biological testing at Johns Hopkins University.

All of the components for the external subsystem have been designed and fabricated, and the final stage of assembly and testing is nearing completion. Says Liu, "Inside the eye, we are working toward a hermetic sealing package of the subsystem, which consists of retinal chip and retinal electrodes. Three generations of the retinal chips have been completely designed, fabricated, and successfully tested in function. Three kinds of electrodes, including platinum electrodes on silicone, platinum electrodes on polyimide, and platinum/iridium electrodes on silicon, are being designed and evaluated in vitro."

The researcher explains that, "Before the entire prosthetic device can be chronically implanted, all the components must be integrated in a biocompatible device. By the year 2000, we expect to have a complete prototype of the prosthetic device so that both long-term-based in vitro and in vivo tests in animals and volunteer human patients can be done."

The group's current research efforts are intended to overcome two challenges associated with the system—providing power to the chip, which is isolated within the ocular cavity, and fabricating the photoreceptors and electrodes on opposite sides of the chip to stimulate the retina. The researchers suggest that, because the cornea is transparent to laser light in any visible wavelength, such a laser could be used to power a chip equipped with photoconducting pixels. They further suggest that by fabricating the photoconducting photovoltaic cells, the photosensing or phototransistor array and the stimulating array could all be placed on a single side of the chip.

WORKING WITH AVAILABLE LIGHT

An artificial silicon retina (ASR) has been invented by brothers Alan Chow, MD, and Vincent Chow, an electrical engineer. The brothers are cofounders of Optobionics Corp. (Wheaton, IL), which is developing the technology. The silicon chip of the ASR is approximately 3-mm diam and 0.001-in. thick and functions as a subretinal microphotodiode array (SMA). The chip contains microphotodiodes that act as microscopic solar cells, each having its own stimulating electrode. The microphotodiodes are designed to convert the light energy from images to electrical impulses that stimulate the remaining functional retinal cells in patients with RP and AMD.

The researchers state that the novel design of the ASR allows it to be "powered solely by incident light, requiring no external wires or power sources." Surgically implanted under the retina, the ASR is designed to produce visual signals similar to those produced by the eye's natural photoreceptor layer. From their subretinal location, the ASR's photoelectric signals can induce artificial biological visual signals in the remaining functional retinal cells. These signals are processed and sent to the brain via the optic nerve. The researchers believe that the device is unique because it functions much like a solar cell, with no external connections and no power supply. The device is powered only by light that enters the eye.

Optobionics' artificial silicon retina is approximately 3-mm diam and 0.001-in. thick.

Animal models implanted with the ASR during preclinical laboratory testing responded to light stimuli with retinal electrical signals and brain-wave signals. The induction of these biological signals by the ASR indicates that visual responses had occurred. Optobionics is presently working in collaboration with the Hines Veterans Administration Medical Center (Maywood, IL), the Louisiana State University Eye Center (New Orleans), and Stanford University (Palo Alto, CA) to enhance biocompatibility and function of the ASR so that human clinical testing may be initiated. To date, the chip will work in the eye for only a limited period of time, but development continues and tests in human eyes are anticipated within two years.

The researchers hope to define the nature of the interface between the retina and the subretinal microphotodiode array. "We've also noticed that the functionality of the device increases over a period of two or three months, peaks at a steady state for several months, and then begins to decline. So we need to find out what's behind that time course," he adds. Currently the device is capable of displaying only black-and-white images, they note, and works best in well-lit rooms. The researchers expect human testing to begin within two years.

"LEARNING RETINA" WOULD ALLOW FINE-TUNING OF IMPLANTS

Two interdisciplinary research teams founded in 1995 by the German Federal Minister for Research and Technology are focusing their efforts on techniques for electrically stimulating retinal cells to produce at least partial ambulatory vision in blind patients. The EPI-RET project, coordinated by Rolf Eckmiller, DrEng, at the University of Bonn department of computer science, developed a micromachined stimulator for implantation within the retinal tissue. The SUB-RET project, directed by Eberhard Zrenner, DrMed, of the University of Tübingen, has developed microphotodiode arrays for implantation underneath the retina.

Zrenner states that the SUB-RET group has succeeded in producing several prototypes of microphotodiode arrays that can be implanted into the subretinal space, and have tested the biocompatibility and stability of the prototypes. "We have developed two surgical techniques, one of which is very novel," says Zrenner. "We have implanted such chips in rabbits, rats, and pigs up to 14 months, and recorded visual potentials from the retina and visual cortex, elicited by infrared response." He adds that a number of challenges must still be resolved. "The chip works only with very bright light and presently we are developing a completely new generation of an active subretinal chip that receives external energy and uses the photodiodes just for switching this energy onto retinal cells." Zrenner notes that the group's progress to date shows promise for development of a functional device in the future. "We are convinced that the concept, in principle, is right. But of course we need a number of additional steps until we will arrive at a product suited to be implanted into a human being since this needs a number of additional developments regarding safety, efficiency, and accordance with regulations valid for medical devices."

The EPI-RET project's Mark I retina encoder relies on computer simulations for RF-filter adjustment using neural nets and for monitoring the input and output signals.

Eckmiller, with Ralph Hünermann and Michael Becker, is conducting studies to develop a tunable retinal encoder (RE) for use with visual implants incorporating a retinal stimulator. This "learning retinal encoder," the EPI-RET researchers say, incorporates tunable spatiotemporal functions and a corresponding perception-based dialog procedure for the implant. Use of such a technique could allow the function of an implanted artificial retina to be optimized for restoring an individual patient's vision.

The initial version of the RE will be located outside the eye on the frame of a pair of glasses. Subsequent designs will allow the device to be embedded in a contact lens. The input of the RE comprises a photosensor array of approximately 100,000 smart pixels and 100 to 1000 technical ganglion-cell outputs that generate impulse sequences to elicit spike trains. An electromagnetic or optoelectronic wireless transmission channel is used to send the encoded ganglion-cell output to the implanted retinal stimulator, which is located adjacent to the retinal ganglion-cell layer.

The learning RE concept is based on using tunable receptive-field (RF) filters to stimulate the spatial and temporal receptive field properties of the retinal ganglion cells. Tuning the RF filters would entail generating RE modification signals to adjust specific parameters of the tunable filters so that the patient's perception of a visual stimulus most accurately represents the actual visual pattern. Although tuning the RF filters must be based on regained perceptions of blind subjects, the researchers recently proposed a method of pretraining the learning retina encoder using visual feedback provided by subjects with normal vision.

Individual microphotodiode located on an artificial silicon retina.

In response to the success of research efforts of the Bonn research team, Intelligent Implants GmbH (Bonn, Germany) was formed in the spring of 1998. The company intends to focus generally on development of the necessary technology platforms for learning neural prosthetic devices, among others. The company also intends to center its initial efforts on the commercial development of the learning retina implant.

CONCLUSION

Until recently, patients could be offered no hope of successful treatment to recover the sense of sight lost as a result of RP or AMD. The near-simultaneous development since the early 1990s of new materials with enhanced biocompatibility and of improved machining and circuit-design techniques is providing the tools that one day could allow vision to be restored to patients with these forms of retinal loss.

The majority of experts agree that the greatest hurdle to artificial retina development is inadequate funding. Neuroprosthesis procedures in the United States continue to be regarded as high risk, limiting the amount of available funds from both public and private sources. Eckmiller comments that, in addition to private funding, the ongoing research efforts at the University of Bonn have benefited substantially from government support as a leading project of the German neurotechnology effort.

Even the most advanced systems now in development, however, will have significant limitations at first. The tiniest of microphotodiodes remains quite large when compared to the natural cones of the human eye. Most researchers note that patients will achieve no more than blurred vision with present technology. And current chip designs are expected to allow only black-and-white vision because of limitations in wavelength detection. And there is some concern regarding potential damage from the implant to the remaining retinal cells. Once past the current threshold, and with adequate funding, continuing advances in materials and nanotechnology are expected to overcome initial limitations. Subsequent generations of implants are expected to provide restored vision with full-color images and with significantly greater resolution.

Gregg Nighswonger is executive editor of MD&DI.


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