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A Solid Foundation

Originally Published MX November/December 2001

EDITOR'S PAGE

The tragic events of September 11 have left their mark throughout the world. Market watchers have looked on with dismay as already-weak sectors have dwindled, while analysts have begun the search for an industry with enough strength to lead the world's economies back from the depths.

In such a climate one might expect that the medtech industry, with its heavy dependence on venture-backed entrepreneurial companies, would be suffering. While no one is making a bundle in today's market, some medtech companies are succeeding despite the challenges.

According to VentureOne (San Francisco), market support for initial public offerings (IPOs) has continued to decline throughout 2001. In the second quarter of the year there were only four IPOs, raising a total of $271 million; in the third quarter, the same number of IPOs raised only $245 million. What is more remarkable, however, is that three of the third-quarter IPOs involved companies in the healthcare sector, including bio-orthopedic manufacturer Wright Medical Group Inc. (Arlington,

The Missing Link

Originally Published MX November/December 2001

COVER STORY

The Missing Link

Return to Article:
GE's Changing of the Guard

GE Medical Systems (GEMS; Waukesha, WI) is looking for the missing link between the kind of diagnostic imaging traditionally accomplished with the company's equipment and the still-futuristic possibilities that may be derived from studies of the human genome.

This link could lead to a quantum leap in the diagnostic process, opening a window on the earliest signs of disease. The identification of these signs might be accompanied by an expanded understanding of the biochemical processes that underlie physical symptoms of disease. If pharmaceutical companies can develop therapeutic agents that snarl the early disease mechanism, they could delay or even prevent the onset of physical symptoms of disease.

In a collaboration with Genometrix (The Woodlands, TX), GE Medical Systems combined microarray technologies with conventional and molecular MRI.

The route to this goal is ripe with opportunity for GEMS. The development of advanced diagnostic tools capable of visualizing early signs of disease will be critically important in identifying patients needed to develop and test new therapeutic agents. Once these drugs have been developed, such advanced tests will be necessary to find

How Small is Small? A Guide to the New Microfabrication Design and Process Techniques

Originally Published MDDI November 2001

How Small is Small?: A Guide to the New Microfabrication Design and Process Techniques

Medical device manufacturers need to catch up on the rapidly evolving field of microfabrication to determine which processes and components are right for their product.

Bill Evans and Robert Mehalso

The term microfabrication is usually defined as the manufacturing of components and devices that are measured in hundreds of microns and that have tolerances of only a few microns. The term also applies to larger parts and assemblies with features that are measured in microns.

So just how small is a micron? Formally, a micron (µm) is one-millionth of a meter; 25.4 µm make up one-thousandth of an inch. The human hair makes its entry at 50 to 100 µm in diameter. It would not be unusual for the tip of a catheter to be less than a millimeter, which is 1000 µm.

But what is a micron in a more tangible way? Though it may sound implausible, many of the dimensions discussed in this article are actually bigger than many realize. People often think of the wavelength of light as being very small. Actually, it is barely "submicron," as the microchip manufacturers would say. Red light has a wavelength of 0.65 µm, or 650 nanometers (nm). Most people routinely handle low-cost products that have features injection molded into them; those feature dimensions are smaller than the wavelength of light.

An injection-molded microfluidic structure for precision flow control.
The rainbow patterns on the common audio CD are created by data pits that are about a half a micron wide, but only an eighth of a micron deep (125 nm). These subwavelength features create a diffraction grating that splits light into its constituent colors as the disc is viewed.

But the manufacturing techniques used in popular consumer products like the CD are not just for the companies with giant R&D and tooling budgets. These techniques—precision machining, micromolding, electrical-discharge machining (EDM), laser processing, and a range of lithographic and electrodeposition methods—can all be used to help medical companies create very small or high-precision parts and assemblies to solve a variety of design and manufacturing problems.

Several technical and medical advancements are increasing the need for very small, close-tolerance parts and assemblies:

  • Minimally invasive surgery devices get into tighter and tighter spots with smaller incisions and with more-complex functions and manipulations. Hence there is a need for more sophisticated miniaturized geometries and mechanisms.
  • The use of light-based treatment and real-time optical diagnosis and imaging has increased the use of fiber optics and other optical systems. This has resulted in close-tolerance alignment and precision-lens molding issues.
  • Lab-on-a-chip diagnostics often rely on a vast array of microfabrication techniques to keep both the size of the sample and the equipment small.
A before-and-after redesign of an integrated electro-optic sensor, for which size, cost, and number of parts were reduced by 90%.

Engineers who are used to thinking in terms of conventional machining, where a tolerance of one-thousandth of an inch—a mil—is considered very tight, need only shift their thinking from mils to microns (about 25 times smaller) and understand that the milling machine or lathe is merely a different machine.

This article is intended for readers who are contemplating the design and manufacture of small parts or mechanisms but lack experience with microfabrication techniques. It focuses on techniques that design engineers in the medical device manufacturing industry can consider using today without too much experimenting and lab work. This article is not about micro- electromechanical systems (MEMS), which to many are synonymous with microparts or nanotechnology. MEMS are generally considered to be micromechanisms etched in silicon and other types of semiconductor materials, and it would require a separate article to describe their fabrication.

SELECTING MICROFABRICATION CANDIDATES

Tables I and II give an overview of the major processes and the materials to which they apply, and suggest potential applications. To determine if a part or assembly is a candidate for microfabrication, manufacturers first need to understand the big picture of the various processes and the geometries they can create.

The processes fit broadly into two categories. Mechanical approaches are the most familiar to those accustomed to creating larger parts. Light and chemical methods take advantage of processes originally developed for the semiconductor industry, as well as high-powered lasers. A common aspect of all vendors who offer these services is that they invest heavily in sophisticated measuring equipment to help control quality. This is known as metrology.

Material
Subtractive Process
Additive Process
Attachment Process
Silicon

Wet etching
Dry etching
Dicing

PVD
CVD
Sol gel

Bonding
Adhesives (organic and inorganic)
Anodic bonding

Plastics

Plasma etching
Ion-beam etching
Laser ablation
Micromachining

LIGA
PVD
Plating
Micromolding

Welding
Adhesives
Friction and shrink fits

Metal

Wet etching
Micromachining
Laser ablation
Dicing
EDM

LIGA
Electroforming/plating
PVD
Laser CVD

Adhesives
E-beam welding
Microwelding
Microsoldering
Laser welding
Sonic welding
Friction and shrink fits

Ceramics and glass

Laser ablation
Dicing
Ion-beam etching

LIGA
Sintering
Laser CVD

Plating
Adhesives (organic and inorgainc)
Soldering
Bonding


Table I. Overview of how microfabrication processes apply to various materials.

MECHANICAL PROCESSES

An electroformed, 4-µm-thick diaphragm, for use in pressure measurement in blood vessels.

Micromachining and micromolding are similar in concept to their nonmicro brethren. A good rule of thumb says that if a design looks like it could be machined or molded if it were larger, then it can probably have the micro version of that process applied to it.

Micromachining. Highly specialized vendors usually perform micromachining with dedicated machining centers. These centers must be housed in controlled environments and are designed to work at significantly closer tolerances and smaller part sizes. Trying to work at tight tolerances by tweaking conventional machines is unlikely to achieve consistent results. Tools and jigs become very important because maintaining good surface finishes and actually holding such small parts become significant factors as size drops.

Micromolding. Micromolding requires both dedicated micro tooling skills and dedicated precision molding machines in a well-controlled environment. Successful micromolding requires two things: the equipment must intrinsically have the required resolution, and the vendor must exercise rigorous control over the materials, processing, and molding itself.

Molding and tooling for small parts are not just smaller versions of their regular molding counterparts, so manufacturers should seek vendors who have already demonstrated their skills on similar systems. Tooling is often created using electrical-discharge machining (see below) or diamond turning. It can be created with surface features below the wavelength of light by using lithographic and electrodeposition techniques (see below).

Variations on micromolding include microembossing, during which a lithographically produced master is typically pressed into polymers in a manner similar to compression molding. Elastomers such as silicone rubbers can also be molded in special equipment designed for processing thermoset plastics.

Electrical-Discharge Machining. EDM is commonly used in toolmaking for injection molding, but it can also be used to create individual parts. It is the erosion of metal by spark discharge—think of it as nibbling away at metal with tiny spark teeth that apply such little force to superhard materials that all the vibration and part-holding issues are greatly simplified.

There are two main types of EDM, wire EDM and electrode EDM. In wire EDM, a very thin wire electrode cuts a 2-D numerically controlled path in a metal blank in a manner similar to a tiny bandsaw. The blank sits in a bath of electrolyte and the wire has to enter and leave the piece just as a bandsaw blade would.

In electrode EDM, a male version of the desired machined cavity (the electrode) is first made and then sunk into the metal block. As a result, very sophisticated 3-D surfaces and shapes can be created. But because the electrode still has to enter and leave the metal block, re-entrant geometries are not usually possible. Electrodes are usually CNC machined in soft graphite or other soft metals for manufacturing ease, but for very-high-precision EDM the electrodes can be shaped with some of the precision light-based techniques outlined below.

In EDM, precision is achieved by two main factors. First, the type of machine used has to be designed for the desired tolerance and operated by someone able to exploit its accuracy; second, in electrode EDM, the resulting part can never be more accurate than the method used to create the electrode.

It is also possible to use slight variations on these themes to broaden the geometric possibilities. For instance, some vendors create rotating jigs to hold cylindrical workpieces in the EDM bath and then manipulate both the workpiece and the wire to cut features around the circumference. Some new wire EDM machines allow variable control of the wire orientation to create 2.5-D shapes.

An injection-molded, integrated micro-optic system—8 lenses and mirror mounts and a fiber connector made to a tolerance of ±2 µm.

Light and chemical processes either use light to directly remove material by high-energy laser vaporization (ablation) or to expose a photosensitive material (a resist) through a mask. The resist is applied to the substrate to a thickness of many mils. The exposed resist is then etched away, giving a precise high-aspect-ratio pattern. A conductive substrate with resist patterns can be put into an electrodeposition bath and metal parts can be "grown."

The accuracy of the processes is affected by several factors, most involving the wavelength of the exposing radiation or how the light is manipulated (masks, beam manipulation, etc.). Visible light can be used for exposure resolutions in the micron range, but UV light, electron beams, and even x-rays (LIGA process) can be used to get finer details and to produce thick high-aspect-ratio structures.

Collectively the photosensitive masking processes are often referred to as photolithography. In principle the processes are similar to the lithographic techniques used to print these very words. (Note that all of the processes described below can be performed using sheets or wafers, which are then sliced up to yield many individual parts.)

Lasers. Lasers are effective in micromachining all types of materials. It is important that the material being machined absorbs the laser energy. For instance, excimer (UV) lasers are used for metals, plastics, and ceramics; CO2 lasers for metals and plastics; and femtosecond lasers for all materials. The laser's power, duration of pulse, and beam manipulation affect accuracy and speed of machining.

For example, optical-lens and shutter systems can be used to ablate axisymmetric 3-D surfaces such as lenses on flat plastic sheets. A variation of this process is used to ablate new lenses onto human eyes in the now popular refractive surgery procedures. The excimer laser ablates a lens shape onto the cornea by exposing it to several rapid pulses of decreasing diameter to sculpt the new optical prescription. In fact, the cornea material is very similar to a commonly used acrylic polymer, PMMA.

More-sophisticated beam shapers can be used to create more-complex 3-D shapes. Although the starting material may be a flat sheet, manufacturers are not limited to 2-D profiles. With the right equipment and in certain materials, the laser can be thought of as the cutter of a multiaxis milling machine. Not only can the 2-D profile be controlled very accurately and with no force applied, but the shape of the cutter can also be altered with lenses or mirrors. The depth of the cut can be controlled with focus or ablation time. This all adds up to the potential to create sophisticated micro 3-D parts in a wide variety of materials. Lasers are especially useful for small plastic parts that would be difficult to produce by other processes or would require costly and time-consuming tooling.

Lithographic Techniques in Silicon. Though originally developed for the semiconductor industry, lithographic techniques in silicon are now used routinely to create geometric parts with submicron accuracy. Some examples are miniature v-grooves, arrays of wells, and tiny gears. Because the substrate is silicon, the technique has the advantage of being able to combine small physical parts and features with electronic circuits to create integrated sensors and powered mechanisms. When combined with electrical function, such parts become MEMS.

Although MEMS fabrication is often regarded as an exotic technology, manufacturers should not dismiss silicon etching. It is useful for the cost-effective manufacture of even small quantities of superaccurate parts.

The process starts with a standard-diameter thin wafer of silicon sliced from a giant cylindrical crystal. A photoresist is coated onto the surface and the desired pattern is exposed onto it through a mask, then developed. The wafer is next immersed in a chemical bath (typically sodium or potassium hydroxide), and the patterned silicon is etched. The etching takes place along the planes of the crystal.

A silicon-etched microfluidic structure, revealing how the silicon has etched down the crystallographic plane.

Silicon crystals are available in various crystallographic orientations that result in different etch geometries. Etching along crystallographic planes is useful in creating superaccurate 2.5-D structures in silicon. This is sometimes referred to as crystallographic etching. Not only is the 2-D profile accurate to a tolerance of about a micron, but the depth of a v-groove can also be accurately controlled.

Usually the desired parts are made in multiple quantities on the wafer—from hundreds to thousands—and then either scribed and snapped or diced using a rotary saw. This is known as wafer-scale batch processing and is an important reason small parts made this way can be so cost-effective. True, the process is expensive per batch, but when spread over hundreds of parts, cost per part becomes very low. Also, tolerances are good on each individual part and across the wafer diameter. Wafers consisting of thousands of parts can be stacked and bonded together to create more-complex geometries.

Lithographic Etching of Other Materials. It is possible to etch a wide variety of materials in a manner similar to silicon etching (see Table I for specific materials). It is also possible to use special resists or patterns that produce 3-D surfaces rather than just cutting a 2-D pattern straight down. For instance, on glass it is possible to etch microlenses this way with a kind of graduated tint-pattern mask exposed onto the surface. This causes the material to etch at different rates at different points on the diameter, creating a curved surface.

Electrodeposition. Electrodeposition is the manufacturing of parts by electrodepositing metals into a mold. Typically, for 2.5-D parts, precision features are made on the mold using lithographic techniques. For instance, hundreds to thousands of intricate, thin-walled metal parts can be made at once using a master mold. The surface of the conductive mold is passivated such that the precision electrodeposited parts can be released.

Complex 3-D parts are generally electrodeposited on a precision-machined substrate. The substrate or mold material is selected so that it will preferentially etch relative to the electrodeposited part. For example, an aluminum mold can be quickly etched away, leaving electrodeposited nickel parts.

SURFACE BUILD-UP TECHNIQUES

With the exception of electrodeposition, most of the above light-based processes are subtractive. It is also possible to add low-aspect-ratio features to the surfaces of microparts using the following techniques. Materials can be built up over the whole surface or in selectively masked areas. For instance, electrical wiring can be added to the surface of a ceramic part by depositing a thin conductive layer onto the surface and then electroplating a thicker layer of gold onto the tracks, making them capable of carrying meaningful current.

Physical and Chemical Vapor Deposition. Physical vapor deposition (PVD) and chemical vapor deposition (CVD) are processes for coating materials onto surfaces. They are typically done in a vacuum chamber. With PVD, many materials can be vaporized with heat or can be "sputtered" onto surfaces with great control over the resultant depth. CVD is similar to PVD but uses a chemical reaction in the vapor or at the surface to deliver and bond new materials. Typically, CVD is useful in the production of many metals and particularly ceramic coatings. It is also possible to use lasers (laser CVD) to selectively bond materials in specific locations where the heat has triggered the necessary reaction.

MANAGING FROM CONCEPT TO PRODUCTION

An electroformed, microfluid-control nickel structure with a 200-µm wall.

Project Management. Most medical manufacturers are well aware that they must consider all aspects of design, manufacturing, and regulatory requirements at the early concept stages to avoid downstream problems. Microfabricated design solutions require that such efforts be increased tenfold.

Several of the processes detailed in this article are relatively immature and chances are that many medical designers are tackling small-part design problems for the first time. If the development team is not well informed, it may miss major opportunities to solve problems in an innovative, cost-effective, and time- efficient way. Companies may seek expert advice for their designers by hiring team members from industries with past exposure to micromanufacturing technologies, bringing in experienced consultants to jump-start the effort, and asking potential vendors for their input on possible solutions early in the design cycle.

Design Management. In the creation of microparts, which comes first, the design or the manufacturing method? The intelligent response is neither. Manufacturers should not design the part and then go looking for a process, nor should they pick a process and design within its restrictions.

Instead, the project should start with an open-minded and informed brainstorming process where all factors are thrown in. Manufacturers should lay out the design freedoms, tolerances, and functional requirements in a way all on the team can understand, then challenge them to be creative with solutions. The partially formed design possibilities can be brought to vendors for critical feedback.

An enlargement of the typical surface quality of electroformed parts (the smaller hole has a 25-µm diameter).

Manufacturers should consider at least three possible processes, and hypothetically walk the potential solutions through all the stages necessary to get to market, soliciting feedback from all those who will need to be involved. This will generate valuable realistic comments on design, manufacturing, scheduling, and cost issues before the team is locked into the consequences of a hastily picked design solution.

Typically, brainstorming and early feasibility studies take about six to eight weeks, and are a great way of rounding up all the project issues. For very complicated designs or parts out on the leading edge of possibility, managers may also want to consider running several alternatives at least part of the way through the design and manufacturing cycle before settling on the final solution.

Design Tips. There is true power in making many parts at once on a sheet or wafer scale. The actual process steps may be expensive, but each batch yields thousands of parts. Sheet- or wafer-scale approaches also work well if building up a series of planar layers can create the design. Alignment between the layers can be better than ±5 µm. Each time a new layer is attached, conceivably thousands of features may have been added to the wafer. Re-entrant shapes are also possible with this approach; engineers must be cautious, however, to match thermal-expansion coefficients between layers of different materials. Caution is also warranted when using modeling and simulation tools such as finite element analysis and mold-flow analysis—they may not be accurate at such small dimensions.

Manufacturers must inspect and review prototypes and early production parts carefully. Scanning electron microscopy is vastly superior to optical alternatives, and is not overly expensive at service bureaus. Literally having the vision to check the progress is invaluable.

Prototyping. Prototyping is a significant problem, as there are rarely good surrogates for the final intended process. Most of the time designers will have to bite the bullet and make smaller batches using the intended technique and accept that it will be expensive and time-consuming.

To help make each prototyping stage more effective, manufacturers must not rush in. Instead, they should take the time for vendor feedback and consider making larger-scale models of the design with cheaper prototyping technologies (SLA, SLS, etc.). If the design is planar with many layers, then a large-scale model can be made quickly using low-cost conventional laser cutting of inexpensive plastic sheeting.

Prototyping in light- and chemical-based processes may be time-consuming, but it has the advantage that parts are produced using the tooling and equipment intended for final production. The process may need scaling up, but once it is proven, moving to production volumes can usually be done quickly.

Prototypes of parts intended for molding pose special problems, as plastics are much harder to machine at very small dimensions. Laser machining the prototypes in the intended materials, or making initial samples in metal, can help prove the geometry at the correct scale.

Vendor Selection. To some manufacturers, a particular geometry might look impossible at first, but somewhere in the world there are probably one or two vendors doing something similar. Manufacturers should look around at other industries or market segments to see who is making something similar to the intended design.

For example, a company was recently attempting to mold a high-aspect-ratio (10:1) capillary tube with an inner diameter of 500 µm for a biotech fluid-handling instrument piece. This appeared to break all the rules of molding, but upon investigation, similar aspect ratios were being achieved in laboratory pipetting systems. A search of these molders revealed two vendors in the United States able to mold the part.

Caution should be taken when using the Web for vendor searches, however. The microfabrication industry is not yet mature. Web sites are often small, obscure, and poorly indexed by search engines, and terminology is not standardized. These factors conspire to make most Internet searches incomplete. Companies are better off using their networks, consultants, and trade publications and associations to probe for vendors.

Manufacturers can lower the risks of vendor choice by taking unconventional approaches. For instance, when choosing between two vendors, how can a project manager objectively determine which is most likely to succeed if neither vendor has been successful before? Both vendors may be equally committed to working towards a solution. Before deciding, collect existing parts created by these vendors that are close to the desired new part size, geometry, or special design issues. Take these parts and subject them to independent testing and inspection. Comparing impartial scanning electron microscope images or structural test reports can help determine who is most likely to succeed.

Manufacturing. When considering the final manufactured cost of a microsystem, be aware that the core microcomponents themselves comprise a relatively small proportion. These may only account for 10 to 20% of the cost, with the balance being 15–25% for measuring and testing during production and from 55 to 75% for component handling, packaging, interconnection, and assembly to other components. Therefore, it is crucial that the design team is working together with the manufacturing team; successful, cost-effective systems will come from optimizing this relationship.

The act of designing any product also causes the design of its manufacturing system—this is especially true for microsystems. A precision active alignment of a few microns during the assembly of a number of parts might force the use of very costly robots or sophisticated inflexible jigs that have to be remade every time required dimensions change. If a similarly functioning design could be created using intrinsically close-tolerance, self-aligning parts (crystallographically etched silicon done at wafer scale by the thousands and then routinely diced, for example), much of the burdensome manufacturing infrastructure and long lead times could be eliminated.

Assembly. Handling small parts can be a difficult issue and should be considered from the beginning. It is likely that features will have to be designed onto the part to facilitate handling at various times, from holding in jigs on machine tools to actually manipulating a part into place by the intended end-user. Forces that are normally small—such as static, thermal, and fluid surface tension—can become big factors.

The fasteners that engineers normally use are avoided in micro-systems because they limit miniaturization and create stress problems. Attachment techniques such as soldering, diffusion and anodic bonding, the use of adhesives (organic and nonorganic), and sonic and laser welding are preferable. It is normal to mix and match such methods in an assembly. Manufacturers should avoid active alignments if possible or do them at wafer scale. Designers must understand and apply the first principles of alignment and issues of overrestraint to avoid building stress and misalignment into the assembly.

If possible, designers should try to leverage equipment that exists in another industry to assemble the product. The semiconductor industry routinely uses robots to put together parts at 5- to 10-µm alignment; even better alignment is possible with the newer machine vision–guided systems.

There is a technique in chip assembly that can align parts to ±2 µm using the surface tension of solder. It may be possible to apply this approach to a micro medical system problem. Gold pads are laid down lithographically onto the target substrate and then coated with solder paste. The chip that is to be aligned and connected with these pads has similarly accurate gold pads also lithographically applied. The chip is placed above the solder pads at ±15-µm accuracy using conventional robots. When the solder is turned to liquid during attachment, the meniscus surface-tension effect balls the solder exactly onto the center of the superaccurate gold pads. The chip then "floats" into alignment that nearly equals the lithographically etched accuracy of the pads. Engineers may not need to be making an electrical connection to exploit this effect in other applications.

CONCLUSION

It will likely cost more and take longer than expected in the front-end design and prototyping to implement a micropart or microassembly. On the bright side, however, the microprocesses can often be directly transferred to production. Therefore, the overall product implementation schedule may be faster and less costly.

Adopting a "get-to-market-right-the-first-time" approach to project management by paradoxically checking often for potential problems is crucial. Mistakes will be made on the ultimate path to success. The key is to prototype, model, create small batches, test, validate, and inspect the design as it moves forward. Iterate, iterate, iterate; seek outside experienced advice; accept mistakes, learn, and move on before committing to final production. That way, the cost-effective product will make it to market right the first time, on schedule.

Bill Evans is founder and principle of Bridge Design Inc. (San Francisco); Robert Mehalso is senior vice president and chief technology officer at Ardesta LLC (Ann Arbor, MI).

Photo Courtesy of Robert Mehalso

Copyright ©2001 Medical Device & Diagnostic Industry

Medicare Bill Gains Bipartisan Support

Originally Published MDDI November 2001

NEWS & ANALYSIS

Representatives Jim Ramstad (R-MN) and Karen Thurman (D-FL) have introduced the Medicare Innovation Responsiveness Act of 2001 (H.R. 2973) to reduce delays in making new medical technologies fully available to Medicare's 40 million beneficiaries.

Ramstad and Thurman also sponsored legislation (H.R. 4395) in the 106th Congress that made landmark changes in the way Medicare integrates new medical technologies. Provisions of this bill were incorporated into the Benefits Improvement and Protection Act of 2000 that was signed into law in December 2000.

H.R. 2973 would create a Medicare Office of Technology and Innovation to improve accountability, openness, and coordination in making timely coverage, coding, and payment decisions. In addition to establishing specific decision deadlines, the bill would require improvements in the timeliness and adequacy of Medicare payment adjustments to account for advances in medical technology and procedures. The use of local codes by Medicare contractors would be preserved to help ensure that local contractors remain an avenue for timely patient access to new technologies.

The bill would also ensure that Medicare payment systems are updated at least annually to reflect changes in technology and expand the use of valid external data in making payment adjustments.

Copyright ©2001 Medical Device & Diagnostic Industry

Managing for Quality

Originally Published MX November/December 2001

GOVERNMENTAL & LEGAL AFFAIRS

Managing for Quality

Enterprisewide management systems can help device manufacturers comply with FDA CAPA requirements.

Marie Fair

In today’s fast-paced economy, managing product quality and customer satisfaction is a tremendous challenge for any medical device company. The ability to manage, correct, and prevent product-quality issues can be a crucial component of a device company’s success or failure. Device manufacturers are held to especially high quality standards by FDA and other government agencies to ensure that their products are safe and effective.

The Federal Food, Drug, and Cosmetic Act requires FDA to conduct biennial quality system (QS) and good manufacturing practices (GMP) inspections of companies that manufacture Class II or Class III medical devices.1 In an attempt to decrease inspection time and sharpen the focus of medical device inspections, FDA developed an approach for conducting inspections under the QS regulation called the quality system inspection technique (QSIT).2

Under QSIT, QS requirements

When to Redesign

Originally Published MX November/December 2001

ADVERTISING, DISTRIBUTION, & SALES

There are several indications that a company’s territory alignment or its incentive plan may be working against it. Any of the following conditions should suggest to medtech executives that it’s time to revisit the alignment of their sales territories.

Vastly different market shares from one territory to the next, particularly if the high-market-share territories have low overall sales volume. High-potential territories typically have lower market share than low-potential territories. If high-market-share territories also have low sales, it is an indication that potential in the company’s sales territories is not balanced.

Vacant territories top sales-performance charts. This may be due to the fact that the vacant territories have huge potential and loyal customers. If the previous sales rep for that territory was earning large commissions because of the large sales base, that rep was probably overpaid, and the territory is probably too big.

Innovations Remake Plastic Injection Molding

Originally Published MDDI November 2001

New materials and equipment improve the molding process and the parts it produces.

William Leventon

A healthy dose of innovation has been injected into plastic molding. The changes have been a boon for medical device OEMs, according to injection molders, bringing more design options, better parts, and more-consistent product batches.

In the injection molding industry these days, the operative word is new—new materials are flowing into new molding machines, which are producing new kinds of parts. New processes are being used, and these processes are monitored by new types of equipment.

Going back some years, medical device manufacturers were often limited to materials developed for the automotive and consumer product markets, according to Mike DeAngelo, manager of injection molding for the Burron OEM Division of B. Braun Medical Inc. (Bethlehem, PA). But more recently, resin manufacturers have been formulating materials specifically for the medical market.

"I think medical [technology] is driving a lot of the new material innovations," says Kelly Stichter, opportunity development manager for Phillips Plastics Corp. (Hudson, WI).

USEFUL PROPERTIES

Products molded for consumers must reflect aesthetic and ergonomic considerations.

The new materials offer injection molders a variety of useful properties. For implantable devices, Inland Technologies Inc. (Fontana, CA) uses Bionate, a biodegradable material from The Polymer Technology Group Inc. (Berkeley, CA). And at Unimark Plastics Co. (Greenville, SC), molders are using a clear plastic to manufacture lens carriers. This new plastic allows customers to check the quality of lenses after they've been placed in the carriers.

For improved chemical resistance, Burron and Bayer Corp. (Pittsburgh) have developed a lipid-resistant polycarbonate material that helps injection-molded medical devices stand up to aggressive chemicals such as those in new chemotherapy drugs. Other materials are designed to handle the high temperatures that medical devices encounter during autoclave sterilization, which is regaining popularity. High-temperature options include PEEK, Radel, Udel, and Santoprene 8000.

To add strength to medical parts, molders are turning to liquid-crystal polymers such as Questra, a strong structural material manufactured by Dow Plastics (Midland, MI). "If you drop a part molded out of Questra on your desk, it sounds like a metal part," says Stichter. The rigid, stable material is particularly good for mechanisms, she adds.

Manufacturers are also boosting the strength of molded parts by using materials that contain special fillers. Glass-filled resins, for example, "make a pretty rigid structure," according to Tilak Shah, president of Polyzen Inc. (Cary, NC). Glass-filled plastics are used to make laparoscopes and other scope-related products.

Fill materials offer more than strength. For example, devices made using radiopaque fill material aren't transparent to radiation. During radiation therapy, Shah notes, this fill material shields the body from radioactive sources.

Few things worry medical device manufacturers more than the possibility of contamination. So Battelle Memorial Institute (Columbus, OH) is working on inert substances to take the place of potentially harmful chemicals that can leach out of polyvinyl chloride (PVC). By replacing these chemicals with soy-based additives, Battelle hopes to minimize the chances that PVC will adversely affect drug purity or potency, explains Kelly Jenkins, program manager of Battelle's polymer center.

The development of molding materials still lags behind that of molding machines, which are more efficient and more precise than ever before.

Unfortunately, the special properties of these materials usually don't come cheap. To keep costs down, many of Unimark's customers are actually shying away from engineering plastics. A few years ago, these manufacturers were making medical devices out of what Joe Pack, Unimark's vice president of sales and marketing, calls "strange materials." This was done mainly for marketing reasons and to differentiate a product from its competitors. But those reasons are no longer sufficient to justify the extra cost of special materials. Customers "have to have a fit-and-function reason for using those materials, or they won't do it," Pack says.

For many OEMs, he adds, the choice of materials is now driven more by price than by function. To get a price break, large medical device companies are making their own deals with material manufacturers. Engineers at these companies try to use only the discounted materials when designing new products.

Manufacturers are also being more careful about using plastic additives. "In the past, you might use a plastic with five different additives in it," Pack says. "Now you don't use the additives unless you have to have them."

For cost-conscious manufacturers, there's at least one additive on the market that's actually designed to reduce costs. This additive, known as MuCell, produces air bubbles in plastic resins, Stichler notes, thereby reducing the weight of finished parts.

PARTS ON A DIET

Material costs are being reduced in other ways as well. "We're asking plastic parts to do more than they did 10 years ago," says Jenkins. "Everything's being reduced by weight and by wall thickness."

Today, Jenkins notes, molders are getting down to wall thicknesses of about 0.02 in.—half as thick as the walls of conventional injection-molded parts. Molding these thin-wall parts requires both new materials and new processing methods.

As their name suggests, high-flow materials flow more easily than the conventional materials from which they're derived. According to Jenkins, high-flow materials include a flow agent that boosts their melt-flow rate to 20–30 g/10 min.

Molded devices have played a large role in the advancement of minimally invasive surgery.

High-flow materials hold up well to the extraordinary pressures generated by thin-wall injection molding. During thin-wall processes, Jenkins says, pressures can reach 40,000 psi, compared with pressures of 10,000–20,000 psi typical of conventional injection molding. Such high pressures can produce tremendous shear forces that damage plastics. But because they flow more easily than ordinary plastics, high-flow materials are subjected to less shear force, which reduces processing damage and helps the materials maintain their ultimate strength.

As material flows, it's cooled by contact with the chilled walls of the mold. Eventually, the cooling process brings the material down to its transition temperature, at which point it stops flowing and solidifies. This happens more quickly in thin-wall molding because the thin mass of flowing material doesn't maintain its heat as well as a thicker mass.

As a result, Battelle and others are working on methods to increase the "flow length" of thin-wall molding materials. In one scheme, directed energy is used to heat the flowing plastic, which extends the time it remains in a liquid state. Another technique features a special high-flow nozzle that increases flow length by ensuring random orientation of injected material.

Molding materials may have come a long way in recent years, but their development still lags behind that of molding machines, contends Gary Hengeveld, vice president of Inland Technologies. In the next three to five years, however, Hengeveld expects plastics manufacturers to gain greater control over the properties of their materials. To-day, for example, a molding material might have a melt-flow index of 10 to 15. "That means that one lot might push real hard and another lot might push real easy," Hengeveld explains. "So your molding machine has to adjust to that."

Hengeveld believes manufacturers will dramatically reduce the spreads of melt-flow indexes in the coming years. Instead of 10 to 15, the spread of a future material may be only 14 to 15. The result: fewer machine adjustments and molded parts with more-consistent dimensions from one lot to the next.

EQUIPMENT AND PROCESSES

Of course, material developments are only half the injection molding story. The other half deals with injection molding equipment and processes, and the drive to make them more efficient, more precise, and more capable than ever before.

One process that's becoming increasingly popular is two-shot overmolding. This process consists of two molding operations that combine to make a single part. First, the basic plastic part is formed. Then, before the part comes out of the press, a second shot overmolds another material onto the part.

Molding accuracy enables manufacturers to design and develop products of great complexity, despite small size or intricate components.

Manufacturers often use two-shot overmolding to add a gripping surface to medical devices. "You get rigidity from the first material, and on top of that you overlay another material that gives the product a softer feel," Shah says. Other second-shot additions include gaskets, bumpers, and materials of different colors.

"Customers who used to get a four-piece part now want a one-piece part in two colors," Pack says. In addition, Unimark uses two-shot overmolding to make syringes with a functional layer and a sterilization layer.

As medical products get smaller, so do the injection molding machines that make them. "We're seeing a downsizing of injection molding equipment," Jenkins says. "Part sizes are driving down machine sizes."

At Battelle, Jenkins and his colleagues have a custom-built machine they refer to as a "desktop" injection molder. Measuring about 2½ ft long and 1 ft wide, this fully functional injection molding machine includes scaled-down motors, drives, and all the other components found in larger machines of its kind.

But in the realm of the small, there's much more to successful injection molding than making tiny machine components. "When shot size is in the milligram range, it doesn't take much screw travel to inject your shot," Jenkins notes. "How do you do that with a great deal of accuracy?" Process accuracy becomes ever more challenging as the size of the molded part shrinks. "If you're dealing with micron-sized features, you don't have to be off much to be out of spec."

Not surprisingly, machines that can do the job aren't easy to build. "In the past, we used off-the-shelf components to make these machines," Jenkins says. "Now they're designed and engineered from the ground up."

Whether they're large or small, old hydraulic molding machines are being replaced by all-electric machines. Electric machines eliminate the danger of oil contamination posed by their hydraulic counterparts, DeAngelo says, which makes them ideal for cleanroom applications. Moreover, he adds, electric machines are as much as 85% more energy efficient than hydraulic machines. And they allow true computer control, which greatly improves shot-to-shot repeatability and accuracy. "We want our products to be the same from the first unit to the 10 millionth unit we make," DeAngelo says. "The electric machines help us reach that goal."

Now, all-electric technology can also control mold tooling. Mounted to the tooling, ac servodrive motors are taking over functions that are usually handled by hydraulic equipment. Besides eliminating the danger of oil contamination, electric tooling equipment is more accurate than a hydraulic cylinder, DeAngelo notes. "With an ac servodrive, you can set [the tool] to move 2.874 inches, and it will move exactly 2.874 inches," he says. "You can't get that type of control from a hydraulic cylinder and fluid. With hydraulics, there's always some slack and some play."

AUTOMATING FOR SUCCESS

DeAngelo says manufacturers need precision accuracy if they want to automate their molding operation. No longer a luxury, automation has become crucial to the success of American injection molders, according to Allan Johnson, manager of sales and marketing for Scientific Molding Corp. (Somerset, WI).

"Because of foreign competition, U.S. molders have become much more automated during the last several years," Johnson says. "And the rate of automation continues to increase. At this point, I doubt if there are any molders that are serious about being competitive that don't have robots and pickers on every press."

These machines can slash the amount molders spend on labor, which accounts for about 30% of the cost of a typical part, according to Bill Pittman, vice president of OEM services for DeRoyal Plastics Group (Powell, TN). In addition, automation dramatically improves the repeatability of the molding process. For instance, Johnson says, "if you're molding metal inserts into parts, those metal inserts are put into the tool exactly the same way each time, which means they'll be in exactly the same location in the plastic part each time."

What's more, the timing of each operation is almost exactly the same every time. "You have repeatability from one part to the next, down to minute fractions of a second," Johnson says. If you depend on a human operator, a task might take 7 seconds one time and 17 seconds the next. In that extra 10 seconds, mold and material temperatures can change. "So you have a potential for changes in part dimensions, part quality, and even the surfaces or aesthetics of the part. But with a robot, those parts are identical time after time."

As manufacturing becomes more automated, inspection and process control are following suit. "A lot of customers are telling us: 'You're required to have your process in control,'" Pack says. "So tools that help us do that are becoming a big deal."

Automated process-monitoring equipment includes computers, sensors, machine vision systems, and coordinate-measuring machines. According to Pack, most molding presses come with a local process-monitoring system. Molders can also purchase off-the-shelf systems that monitor process variables such as time, temperature, pressure, and position.

Process monitoring "is a big selling point for us," says Pittman, whose company uses an off-the-shelf system that keeps tabs on mold temperatures, water pressure, injection pressure, and cycle times. The data are collected and stored so the company has a detailed history of every part it makes. "If we make a bad part, we can go back and look at our process to see why the part was bad," Pittman says.

Monitoring systems also enable molders to analyze process and part-dimension data in real time. By contrast, Johnson says, it might take a human inspector half an hour to go through all the manufacturing data. And even then, the inspector might not be able to interpret the data without calling in someone else.

If a process variable moves out of its preset range, an automated monitoring system can set off an alarm or shut the press down until a technician looks at it. The molding operation can also be set up so that when a process variable moves out of range, the parts made during that time are separated from the rest of the batch.

The process deviation "might not have been enough to push the parts out of spec, so I might have thrown away good parts," Pack says. "But I'd rather get them out of the stream so I'm sure I'm not shipping any defective parts. If a customer gets a bad part from us and that part gets to one of his customers, we've lost him for life." Not to mention, Pack adds, "we could be involved in a lawsuit."

Some of Unimark's customers want written certification that the molding process was in control the entire time their parts were being made. In addition, customers are now asking for process data. No problem, Hengeveld says; thanks to PC-based controllers, it's easy to send process information to customers who want it.

In the past, many machine controllers used a language specific to one type of machine. But with the spread of PC-based controllers, Windows software has become common in molding equipment. "This lets you download process data into a normal computer and send it to a customer," Hengeveld explains.

CONCLUSION

Injection molding has been changed by a host of new technologies aimed at improving the process and its products. New materials offer a variety of properties and increase the options of designers. New molding techniques and machinery turn out better products and hold costs down. And sophisticated monitoring equipment keeps a close watch on process variables to boost accuracy and repeatability. Taken together, these innovations add up to a boon for medical device OEMs shopping for injection molding services.

William Leventon is a New Jersey–based freelance writer who frequently covers the medical device and diagnostic industry.

Copyright ©2001 Medical Device & Diagnostic Industry

Anaesthesia and Respiratory Equipment Makers Must Adapt to European Market

Originally Published MDDI November 2001

NEWS & ANALYSIS

Despite the relative stability of revenues in the anesthesia and respiratory equipment market over the last few years, a study by Frost & Sullivan (Foster City, CA) suggests that significant changes may lie ahead. The study values the European market—including anesthesia machines and workstations, multiparameter patient monitoring systems, and ventilators—at $295.8 million in 2000. The market is expected to reach $323.6 million by 2004 as prices stabilize and unit sales continue to increase.

Market maturity, however, could require manufacturers to explore new ways to increase sales. One major challenge, according to the study, will be to identify products or innovations that will spur replacement purchases. Computer-based features are expected to have a significant impact on market growth. According to the study, Europe is going through a period of increasing acceptance of computer technology. The challenge will be to understand the extent to which doctors and anaesthesiologists will use such features.

The study also found that the market is in a period of consolidation. Because even a small gain in market share can be vital in a mature market, consolidation represents a major challenge for all the market players, according to Frost & Sullivan.

Copyright ©2001 Medical Device & Diagnostic Industry

Six Steps to an Effective Privacy Program

Originally Published MX November/December 2001

GOVERNMENTAL & LEGAL AFFAIRS

Six Steps to an Effective Privacy Program

Establishing a company privacy and security program can help a device manufacturer comply with newly enacted privacy laws throughout the world, but it also offers the potential for gaining a significant competitive advantage. An effective privacy program can help generate customer and patient trust, because customers will feel confident engaging in transactions involving personal information, and patients will be more willing to provide such information. Following are the key steps involved in developing and implementing a privacy program.

1. Create and Empower a Task Force. Organize a small, crossfunctional task force of high-level decision makers to oversee the program and its deployment team. Make sure the task force has the support of senior management.

2. Establish a Deployment Team. This team should be crossfunctional and should include at least one project manager.

3. Conduct an Assessment. Identify all areas within the company where personal information

Imbalanced Workloads

Originally Published MX November/December 2001

ADVERTISING, DISTRIBUTION, & SALES

Workload imbalance exists in the sales forces of many medical device, diagnostic, and medical supply companies. The figure below shows the estimated workload for a medical sales force with 185 territories. The account workload in each territory has been calculated and indexed on the vertical axis.

The territories have been sorted from highest to lowest workload, and each territory is plotted as a point along the curved line on the graph. The "average territory" line on the graph represents the annual workload capacity of one salesperson. The territory with the highest workload on the graph has more than twice the workload of the average territory. Conversely, the territory with the lowest workload has less than 40% of the workload of the average territory. More than 50% of the territories have workloads that deviate by more than 15% from the average.

Alignment imbalances like those shown in the figure are typical. Such imbalance leads to suboptimal sales results.

Workload imbalance in medical sales territories leads to suboptimal sales results. Source: ZS Associates (Evanston, IL).

Copyright ©2001 MX