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Study Indicates that Bacteria Adhere Poorly to Soft Surfaces


Study Indicates that Bacteria Adhere Poorly to Soft Surfaces
Daniel Grace
Researchers at MIT discovered that bacteria adhere better to hard surfaces -- a revelation that could influence future efforts to combat biofilms on medical devices.

Contrary to assumption, bacteria exhibit poor adhesion to soft surfaces and good adhesion to hard surfaces, according to a new study conducted by researchers at the Massachusetts Institute of Technology (MIT; Cambridge, MA; This finding could influence future efforts by medical device OEMs to combat biofilms—bacterial clusters that often form on catheters, among other medical devices.

Bacterial surface attachment is the first step toward the formation of biofilms, which are a major cause of hospital-acquired infections. Biofilms are sticky and resistant to traditional antibiotics; often the only certain way to remove them is by physical scraping, which is not an option with medical implants.

In an attempt to learn more about bacterial adhesion, the research team—materials science and engineering specialists—incubated E. Coli and Staphylococcus bacteria on polymer films with various precisely controlled stiffnesses. Though the two types of bacteria are significantly different in terms of structure, both demonstrated a similar reaction to surface mechanics in the study. The number of bacteria that adhered to a stiff surface was orders of magnitude greater than the number that adhered to a soft surface.

“In the past, researchers have investigated several different variables in attempting to learn more about what causes bacteria to stick [to surfaces],” says Jenny Lichter, an MIT graduate student and a primary member of the research team. “But this is the first time anyone has controlled for mechanical stiffness.”

Specialized tools, such as atomic force microscopy, have been used in the recent past for studying how mechanical force affects cells. Until the MIT study, however, bacterial cells had never been approached as an appropriate subject for enlisting such tools. It was assumed that bacterial cells, relatively simple compared with animal cells, didn’t have the internal structures necessary to respond to mechanical stimuli. The MIT researchers spent two years experimenting and controlling for all regulators of adhesion in order to ensure that mechanical effects were being observed and not some other factor.

The soft polymer films used in the study were created by dipping an object or device into water-based solutions of biocompatible polymers, a method that could potentially be used to manufacture antibacterial coatings for medical devices. In addition, the soft films could incorporate antibacterial coating approaches introduced by other researchers, such as water-repelling designs, bacteria-bursting capabilities, and embedded silver nanoparticles.

The study’s findings could also be used to benefit future research. Since bacteria are difficult to study because they can’t be cultured in laboratories using traditional methods, stiff coatings could be used to promote bacterial growth. It’s unclear why bacteria adhere better to stiffer surfaces, but upcoming efforts by the researchers could include attempts to answer that question, according to Lichter.

Copyright ©2008 Medical Product Manufacturing News

System Uses Tongue to Drive Wheelchair


(click to enlarge) Maysam Ghovanloo developed the tongue-drive system to enable victims of spinal cord injuries to live more independently.

Most people don't give a second thought to how their tongue moves. But the powerful muscle can go beyond speech. One professor at the Georgia Institute of Technology (Atlanta) is capitalizing on this idea with a device that helps those with disabilities control their wheelchair with the simple movement of the tongue.

The tongue-drive system, developed by Maysam Ghovanloo, is designed for people who have brain function, but have lost the connection between their brain and the rest of their body. Victims of spinal cord injuries sometimes have this condition. The goal of the device is to enable users to live more independently.

Other technologies that aim to help patients include brain–computer interfacing and eye trackers. Brain–computer interfacing records and analyzes the brain's electrical activities to determine the person's intentions, such as driving a wheelchair. But the process is invasive, because the electrodes must be implanted.

Eye tracking places a camera in front of the user's face. Image-processing software focuses on eye movements, but the system can interfere with vision. A tongue-touch keypad for communication and navigation has also been on the market, however it requires a tiring application of tongue pressure.

Ghovanloo, an assistant professor at Georgia Tech's School of Electrical and Computer Engineering, says the tongue-drive system solves these problems. It is noninvasive and based on tongue movements, not pressure. A magnet placed inside the mouth works with external sensors and wirelessly transmits signals to a portable computer. The sensors control the motion of a cursor on the computer screen and can function similarly to a joystick when powering a wheelchair.

Users can talk while driving their wheelchair or accessing their computer. The researchers have differentiated the types of commands associated with tongue movements versus those made during speech, so there's no interference. The system can be trained to execute commands based on unique tongue movements. It also goes into standby mode when the user is eating or sleeping.

The only object inside the mouth is a tiny magnet. Depending on whether the user wants the device temporarily or permanently, the magnet can be placed on, implanted in, or pierced through the tongue. “When they're testing it in our lab, I haven't been able to convince my students to get a tongue piercing,” says Ghovanloo. “We add a little bit of tissue adhesive onto the top of the small magnet and place it on the surface of the tongue. It attaches to the tongue for a few hours, and then it comes off.”

A magnet placed inside the mouth relays tongue movements to an external sensor, which transmits signals to a portable computer.

To use the system permanently, the patient's tongue would be pierced, and the magnet would replace the jewelry normally found atop the piercing. Another option is tongue implantation, which Ghovanloo has not yet attempted. In that case, a magnet would be inserted under the tongue with a hypodermic needle.

Two magnetic sensors are located outside the mouth. Ghovanloo envisions a headset-style device that has magnetic sensors on the tip.

“Even though this prototype is fine for getting the job done, from the aesthetic point of view it could look much nicer,” says Ghovanloo. “Eventually we would like the headset to look like a nice headphone. We're working on a very fashionable headset to be designed by a professional industrial designer.”

The device's function has been demonstrated, and researchers are working on providing the user with proportional control as opposed to the current switch-based system. Proportional control works like a joystick, making turning and adjusting wheelchair speed easier. The further forward the joystick is pushed, the faster the system moves. The switch-based system involves pressing keys to drive the wheelchair.

They also plan to add commands and simplify the graphic user interface. “One advantage of this system is that you can associate any arbitrary tongue movement to a particular command,” says Ghovanloo. “If you move it forward, left, and down, that [combination] could be a command.”

Ghovanloo says there's room for improvement. The researchers have already conducted three rounds of trials with student volunteers who had no disabilities. Their next goal is to get feedback from people with disabilities.

An internal version of the tongue-drive system has also been designed in the form of an orthodontic brace. The entire system is placed inside the mouth on the outer surface of the teeth. It will have a rechargeable battery and a much smaller area of sensors. Ghovanloo anticipates a functional and more-attractive version to be ready in about 12–18 months.

Ghovanloo has been working on the patent-pending system with Georgia Tech graduate student Xueliang Huo. Their research is being funded by the National Science Foundation, and the Christopher and Dana Reeve Foundation.

Copyright ©2008 Medical Device & Diagnostic Industry

Extruded Tubing Designed for Balloon Production

Producing balloons used for angioplasty catheters calls for tubing that has more stringent requirements than that used for other uses, such as catheter body or strain relief. To ensure that the proper tubing is selected, it is essential to understand the requirements for balloons as well as the balloon-forming process.

Angioplasty Balloon Catheters

Balloon catheters are used for both plain old balloon angioplasty (POBA) as well for stent delivery and deployment. The catheters are typically inserted through a narrow-gauge introducer (e.g., 5 or 6 Fr) into the femoral artery, and the balloons placed in a constricted passage within the stenosis. As a result, the balloon must have very thin walls, typically on the order of 0.001 in. (25 µm). However, because calcified stenosis can be difficult to open, the balloons must be tear-resistant and have high burst pressures, with nominal pressures typically ranging from 6 to 8 atm and rated burst pressures in the range of 12–20 atm.

Multiple deployments may be necessary, so balloon fatigue is also a factor. Finally, to prevent damage to vessel walls caused by overinflation, balloons must have reliable diameters along the length of the balloon at nominal pressure. They must also be only semicompliant (e.g., limited increase in size past the nominal pressure on the order of 5–10% from nominal to rated burst pressure). To create balloons with these characteristics, high-quality tubing with uniform properties is a key requirement.

The Balloon-Forming Process

Figure 1. During the stretch blow molding process, the polymers are stretched as shown.

Balloon forming is done through a process called stretch blow molding in which polymer-based tubing is stretched under pressure and at an elevated temperature in a biaxial fashion both longitudinally and radially. The temperature and pressure vary by material and balloon diameter. For example, nylon 12 balloons are formed at 170° to 200°F, and a 3-mm nylon 12 balloon may be formed at 35 bar while a 10-mm balloon is formed at 15 bar. The intent is to mechanically stretch the polymer chains so that they provide maximum strength to the balloon as well as resist further growth. The result is a well-defined diameter.

Figure 2. (click to enlarge) As blow molding stretches the polymer, the strain remains relatively constant.

The polymer orientation in the tubing should be randomized. During the blow molding process, the polymers are stretched as shown in Figure 1. During the stretching process, the strain will be relatively constant as shown in Figure 2. Once the polymer strands become maximally stretched, the strain increases dramatically. At this point, the material has its greatest strength and will resist further growth. Typically, there is an expected stretch ratio for a given axis and material (e.g., approximately 6× radial and 4.7× axial stretch for nylon 12).

In the balloon-forming process, a parison is placed into a mold as shown in Figure 3. A parison is a piece of tubing in which both ends have been necked down in a controlled process in order to achieve three functions:

  • Control where the balloon forms on the tube.
  • Improve formation of the cone section.
  • Allow for smaller neck outside diameters (ODs) needed for low-profile catheters.
Figure 3. (click to enlarge) In the balloon-forming process, a parison is placed into a mold as shown (a). A secondary stretch at lower pressures is often used after the main balloon body is formed in order to create thinner cones and neck wall thicknesses (b). The formed balloon is cooled using chilled circulating water in a surrounding jacket while maintaining a high internal pressure to set the dimensions (c).

The parison is then stretched while pressurized internally with clean, dry nitrogen and under a controlled elevated temperature from surrounding heating elements. This process promotes balloon formation. Note that the temperature is lower than the melting point (nylon 12 Grilamid has a melting point of 352°F, for example), which would cause material flow and randomization of the polymer chains. The temperature is typically in the range of the glass transition temperature for the tubing material. A secondary stretch at lower pressures—typically one-third or less of the forming pressure—is often used after the main balloon body is formed in order to create thinner cones and neck wall thicknesses.

Finally, the formed balloon is cooled using chilled circulating water in a surrounding jacket while maintaining a high internal pressure to set the dimensions.

Quality Issues for Balloons

Typical quality issues faced in the production of balloons include gel spots, fish-eyes, impurities, drag lines, zipper lines, bowing, and visual imperfections. Quality is critical. These issues can lead to failure such as early burst, fatigue, or incorrect dimensions. Such failures can compromise patient safety as well as increase procedure time, both primary concerns for clinicians.

Gel spots are typically the result of impurities in the tubing or of broken polymer chains caused by shear stresses within the extrusion system. The former can be handled by proper filtering within the extrusion system. The latter is a function of the extruder design. In the reduction of pellets to melt to tubing, right angles or extreme transitions can cause shear forces that will break the polymer strands. Once broken, the resulting material has different physical properties and, in effect, constitutes an impurity that may show up in the balloon wall and increase its propensity to burst at lower pressures or fatigue early. One situation in which this can happen is when a larger-bore, 1-in. extruder is used to make the smaller microbore tubing (typically 0.15 in. OD or less) needed for balloons.

Burst pressure is dependent on balloon material and hoop stress, which is a function of wall thickness and balloon diameter. Thicker walls increase burst pressures while larger diameters increase hoop stress and result in lower burst pressures. Defects in the wall such as gel spots and fish-eyes cause a weak point in the material and result in lower burst pressures. For example, a 3-mm balloon with a 0.00065-in. wall made from nylon 12 may have an average burst of 25 atm but can fail at 20 atm.

Fish-eyes can result either from moisture in the tubing or from overstraining the material in the forming process. Moisture in the tubing may vaporize during the elevated temperatures in the balloon-forming process, resulting in voids in the balloon wall. Overstraining the material, i.e., going past the optimal stretch ratio, can lead to microtears similar in appearance to the voids. Similar to gel spots, fish-eyes can lead to lower burst pressures and early fatigue. Moisture can be prevented by drying the pellets prior to extrusion and storing tubing in a clean, dry, and dark environment. Overstraining can be addressed through careful control of inner and outer tube diameter, as well as concentricity so as to stay within the stretch ratio during the forming process.

Impurities are embedded foreign materials. Impurities can lead to weak points in the balloon wall and can create visual imperfections.

Drag lines are a result of narrow grooves or scratches created on the outside of the tubing during the extrusion process. This can happen if a particle becomes stuck on the extrusion die head and causes furrows as the tubing emerges. Drag lines can result in a rib along the balloon, which can, in turn, result in bowing of the balloon under pressure or can lead to lower burst pressures.

Zipper lines can result if the tubing chatters along the extrusion die head as it emerges. If the engagement between the tubing and the die head isn't constant, a series of depressions can be created. These depressions enlarge to form a series of visual imperfections called zipper lines on the formed balloon.

See Video of the Stretch Blow
Molding Process

Bowing of the balloon under pressure can result from either drag lines, as described above, or uneven wall thickness. Sometimes referred to as banana shaped, a balloon will not grow symmetrically under increasing pressure in such cases but rather bows to one side.

Requirements for Balloon Tubing

Tubing for balloons must be free of impurities and moisture. It must have uniform inside diameter and OD as well as concentricity. Specific mechanical properties include tensile strength and elongation. Typical tubing provided by extrusion vendors will have dimensional and visual specifications, but will not address these other requirements. By contrast, balloon tubing requires more-stringent production methods. The polymer materials normally used for balloon catheters include nylon, Pebax, polyethylene terephthalate, and polyurethane.

How Tubing Is Extruded

Figure 4. (click to enlarge) Typical extrusion process.

Extrusion has been well described in many articles, but an overview here is useful. Pellets are dedusted, dried, and placed into the extruder hopper as shown in the diagram in Figure 4. From there, the pellets drop down the throat into the barrel. A turning screw creates a high-viscosity molten polymer using both mechanical friction heat and applied heat from heating elements. The screw transports the material along the barrel and through the extrusion head die. The tubing is then cooled and solidified as it passes through the air and into a water bath. The size of tubing is determined by the die head and the drawdown that occurs with tension on the extrudate.

The need for careful preparation of the pellets for extrusion cannot be overstated. Any dust or foreign materials can become embedded in the tubing as it is extruded. To complicate matters, the injection molding approach used to create the pellets often creates a static charge that attracts dust. To compensate, pellets are typically dedusted in a system called, prosaically, a deduster. Dedusters act through a combination of air cleaning and antistatic measures to both remove dust and reduce the propensity to attract dust.

Another issue for pellets is removing moisture and keeping the material dry. Typically, the polymer material used for balloon production is hygroscopic and readily picks up water from the surrounding atmosphere. As a result, it's important to dry the pellets as well as to store them in a sealed, dry container. Often pellets are redried just before going into the hopper. Redrying the pellets can be especially important for balloon tubing to prevent moisture from creating fish-eyes. Dryers can range from simple ovens to complex temperature-controlled systems with convection heating.

The screw-and-barrel system is one of the most critical aspects of the extrusion system. Not only is it responsible for creating and transporting the polymer melt to the extrusion die, it must keep the melt in a homogenous state. Any deviation will result in poor quality and a material change in properties. As described, shear forces can result in breaking of polymer chains. Poor flow areas and eddies where material can gather can result in the overheating and burning of material.

The die head and drawdown used for sizing the tubing is an important factor in extrusion. Different combinations of die heads and drawdown can create the same size tubing. For example, a 0.1-in. OD tube can be made with a 0.15-in. die, which would require a drawdown ratio of 1.5. If the die is 0.175 in., the drawdown ratio would be 1.75. However, drawdown can induce longitudinal orientation of the polymer strands, the degree of which is dependent on the extent of the drawdown. This orientation or, stated differently, decreased randomness of the polymer chains, affects mechanical properties such as tensile strength and the degree of stretch in the balloon blow molding process. Consistency in mechanical properties is vital for balloon production.

Another important requirement is consistency in the ID and OD of the tubing as well as concentricity. As described above, the polymer material will have an optimal stretch that achieves the desired balloon properties. If the diameter is undersized and the stretch is too great, the balloon may burst during formation or result in fish-eyes. If the diameter is oversized, the resulting balloon will not be fully formed and will still have room to grow under pressure. If the balloon grows under pressure, it can result in possible complications such as overextension of the vessel wall or difficulty in catheter removal through the introducer sheath. High-end extrusion systems typically have computer-controlled monitoring of the tubing diameters and a feedback mechanism for controlling these key dimensions.

The selection of a good extruder is critical to successful extrusion. Large extruders increase the risk of thermal and mechanical degradations as described above. Microextruders (1/2 in. or smaller) reduce almost all material degradation risk due to the smaller size, ultimately increasing yields significantly. Microextrusion also makes it easier to achieve a random orientation of polymer chains and lower axial alignment, which facilitates the balloon-forming process. Repeatability is also a key factor in successful extrusion. The tighter tolerances achievable with a microextruder enable less lot-to-lot variability.

Test Methods for Tubing

As discussed, polymer tubing for balloon formation must have consistent mechanical properties. These properties are a function of the degree of polymer randomization as well as dimensions. The mechanical properties of tubing can be evaluated through a number of methods, including dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and a universal test machine (UTM). DMA is used to measure the stiffness and viscoelastic properties. DSC is used to determine the amount of heat required to raise the temperature of the material and can be used to determine phase transitions such as glass transition or melting point. A UTM is used to measure, among other things, tensile characteristics.

In addition, the tubing material must also have a narrow mean molecular weight distribution (MWD). MWD is a function of the consistency of the polymer strand length. Any degradation or breakage of the polymer strands results in molecules of different lengths that can substantially change the material properties and their consistency. MWD can be measured by gel permeation chromatography.


High-quality tubing is critical for successful high-yield balloon production. Because it has more-stringent requirements compared with other extruded tubing, greater care must be taken in the selection of extrusion equipment and processes used if performed in-house or in the selection of an outside vendor.

Eric Mabry is the vice president of sales and marketing for Interface Catheter Solutions (Laguna Niguel, CA). He can be contacted at

Copyright ©2008 Medical Device & Diagnostic Industry

Hydrogel Technology Offers Flexible Characteristics


Hydrogel Technology Offers Flexible Characteristics

Despite consisting primarily of water, a hydrogel can be manipulated to demonstrate 100 to 1000 times the strength of competing gels, according to the product’s manufacturer, AGT Sciences Ltd. (West Yorkshire, UK; The gel can be employed in a range of medical applications, including wound care, drug delivery, tissue engineering, and orthopedics.

The flexible properties of the gel derive from the covalent bonds formed by two elastic-like molecules. Modifying the number of bonds enables the manipulation of the gel to exhibit the desired physiochemical properties. It can be altered to be thick, thin, or sticky, depending on the application. The hydrogel can also hold molecules of other substances, regardless of whether they are water soluble or water insoluble, according to the company.

Although the polymer gel can be supplied in either liquid or solid form, the latter can have a water content exceeding 90% and still exhibit high mechanical strength. It also can be extruded into films. Furthermore, the cross-linking reaction is unaffected by the presence of other substances and is reversible, if desired. Additional properties of the nontoxic hydrogel include temperature and radiation resistance.

AGT is exploring a variety of medical applications for the hydrogel through its extensive R&D endeavors. Among its focuses is the use of the gel in wound dressings. The company anticipates that the product could be incorporated into diagnostic dressings designed to relay such data as the pH of the wound bed, presence of enzymes, and level of bacterial infection. Sustained release of infection-fighting agents from antibacterial dressings could also be facilitated by the hydrogel.

Copyright ©2008 Medical Product Manufacturing News

Contract Manufacturers Get Active with Combination Products


Contract Manufacturers Get Active with Combination Products

Stephanie Steward

Orthobiologics, a field of combination products, combines traditional orthopedics, such as a hip implant (pictured), with bone-growth stimulators such as bone morphogenic proteins. The field makes up 13% of the orthopedic market, and sales are expected to double by 2013.

Most contract manufacturers are adept at juggling and coordinating a variety of design, testing, and manufacturing tasks. This skill set is put to good use when tackling an OEM’s combination product, which can present double the challenges and regulatory requirements of typical devices. Among the challenges that contract manufacturers face are keeping up with the latest developments in drug delivery and adopting new technologies to get customers’ designs to market.

As combination products have become more sophisticated, so have methods of drug delivery. Tapemark (West St. Paul, MN) is a contract manufacturer that specializes in custom converting of medical devices and components utilizing such materials as films, nonwovens, and foils. In its work with transdermal combination products, the company has embraced new design techniques that enhance drug delivery, according to Julie Karlson, marketing manager. Some of these techniques include adding batteries or iontophoresis. For example, a transdermal patch that incorporates iontophoresis uses a small microprocessor-controlled electrical charge to deliver a drug. The microprocessor can enable dosing to be programmed into the device or controlled by the patient. “All of these techniques reflect the strong trend toward active, rather than passive, transdermals,” Karlson says. The company is also noticing a related trend of manufacturers focusing on how to make transdermal patches more comfortable and safer for patients to wear for extended periods of time, she adds.

In addition to getting involved in manufacturing noninvasive, active transdermals for applications like pain therapy, many contract are also monitoring the emerging orthobiologics market. One such company is WuXi AppTec (St. Paul, MN), which specializes in testing medical devices but also offers manufacturing services for devices as well as cellular therapeutics, tissue-based products, and more. “Drug-enhanced devices drove the initial growth of the combination product market, but demand for more-localized drug-delivery products is driving the next wave of combination devices,” says Dean Enrooth, vice president of business development, medical devices, at WuXi AppTec.

Because of the massive aging population, the orthobiologics field, in particular, is demonstrating major growth potential, according to Enrooth. Orthobiologics are products that combine traditional orthopedics, such as knee and hip implants, with bone-growth stimulators such as bone morphogenic proteins.

Synthetic bone-graft substitutes and bone-growth stimulators do not require donated human tissue, therefore reducing the risk of disease transmission. The field is rapidly gaining acceptance because of its potential to improve quality of life and reduce health costs. It already makes up 13% of the $33 billion orthopedic market and sales are expected to double by 2013, according to a report from market research firm Espicom.

In addition to the projected growth of fields like orthobiologics and active transdermals, the forecast for the combination products market as a whole is optimistic. “The total market for drug-device combinations worldwide is expected to rise at an average annual growth rate of 13.6% to $11.5 billion in 2010,” states a report from BCC Research.

Copyright ©2008 Medical Product Manufacturing News

Ask and (Maybe) You Shall Receive

It seems as though technological developments are constantly pushing the boundaries of medical device capabilities, applications, and package size. But some patients who rely on critical devices, such as insulin pumps, bemoan that while product functionality is advancing at a spectacular pace, aesthetics and design are lagging far behind.

Amy Tenderich, who writes the popular blog DiabetesMine (, posted an open letter last year to Apple CEO Steve Jobs, soliciting him to have his team tackle medical product design. In it, Tenderich lauds the iPod for revolutionizing consumer electronics with its functionality, intuitive interface, and, perhaps most of all, sleek design. She wonders: Why can’t these user-friendly features and eye-catching designs be applied to critical devices, too?

“In short, medical device manufacturers are stuck in a bygone era; they continue to design these products in an engineering-driven, physician-centered bubble,” Tenderich writes. “They have not yet grasped the concept that medical devices are also life devices, and therefore need to feel good and look good for the patients using them 24/7, in addition to keeping us alive.”

Building on the momentum generated from last year’s post, Tenderich this year held a design challenge. Submissions from a range of amateur designers included a glucose-strip dispenser with a built-in disposable container modeled after Pez candy dispensers and a device for young children that gives them and their caregivers easily identifiable color cues to indicate glucose levels.

Obviously, feasibility is likely an obstacle to actualizing such designs. But hosting and drawing inspiration from such contests could be a valuable way of appeasing users and creating a product that they genuinely like. The submissions to the DiabetesMine challenge proved to blend aesthetics and practicality—not to mention that they were designed in many cases by actual users of diabetes devices.

For insulin pumps and similar products, functionality and accuracy are paramount. However, a user-friendly and inconspicuous design can potentially go a long way. These attributes can increase patient compliance and improve quality of life. They can even cultivate brand loyalty and promote differentiation in the marketplace.

“If a medical device uses some of the same interaction metaphors as a consumer electronics product, then the medical device may be easier for the patient to learn and safer to use,” muses Matthew Jordan, insulin pump user and director, research and interaction design, of Insight Product Development (Chicago; “Similarly, consumer electronic aesthetics, when applied to medical devices, may make the device seem more familiar and approachable for the patient.”

Although development times and functionality concerns can impose certain limitations on critical device design, it might behoove OEMs of diabetes products and other such “life devices” to try and better tap into patient needs and wants. Through blogs and amateur contests, patients are expressing their dissatisfaction with current models. Be the first to heed the call.

Shana Leonard, Editor
Copyright ©2008 Medical Product Manufacturing News

Coating Technology Improves Implant Osseointegration


Coating Technology Improves Implant Osseointegration

Shana Leonard

Photo by Gary Meek

As new waves of aging, active baby boomers enter their sixties each day and a rising number of younger patients require joint-replacement surgery, the need for more-durable and longer-lasting implants is becoming increasingly urgent. In an effort to address this demand, a research team at the Georgia Institute of Technology (Atlanta; has developed a bioactive coating technology that facilitates osseointegration, which is essential for a successful and long-lasting implant.

When a synthetic material is implanted, the body reacts to the foreign substance by absorbing proteins on the device and consequently causing an inflammatory response, explains Andrés Garcia, professor at the university’s Woodruff School of Mechanical Engineering and member of the research team. To prevent this nonspecific absorption of proteins, the researchers applied a polyethylene glycol (PEG)–based polymer brush—which Garcia likens to the upright bristles on a toothbrush—to the implant. The polymer chain is then polymerized on the titanium surface in a straightforward reaction.

The researchers next introduced specific biological motifs to the nonfouling surface in order to target cellular receptors. Garcia notes that presenting biological motifs is not a novel idea; research has typically focused on an arginine-glycine-aspartic acid (RGD) adhesive sequence. However, recent data have emerged indicating that this approach is not effective in vivo.

“Our original hypothesis was that the reason these short peptides do not work in vivo is that they target the wrong receptors in the cell,” Garcia explains. “What we previously did was developed other biological motifs that have much higher specificity for the adhesion receptors. So, in addition to the coating, we then directly compare the peptide we developed to the standard in the field—which is the RGD motif. We showed that by having a more-specific peptide on this titanium surface, we can get a significant enhancement in biological function compared to surfaces that have RGD, [which] essentially didn’t do anything,” he continues. Garcia adds that the functionalized surfaces even outperformed unmodified titanium in the experiments.

The dual approach of the coating followed by the specific biological motif yielded better growth of bone around the implant and created a more-robust attachment and integration of the device to the bone, according to the researchers. Although pleased at the resulting osseointegration of the titanium implant, the team views the technology as a generalized platform. “We showed that we can [apply the technology beyond peptides] by varying the presentation of the bioactive molecule in terms of the density and the coating, and we showed corresponding differences in the osseointegration or the biological performance of the device,” Garcia says.

Although the Georgia Tech researchers used titanium to prove their hypothesis, the technology can be applied to a range of materials, among them are ceramics, glass, metal, and any material that has an oxide layer.

Copyright ©2008 Medical Product Manufacturing News

Location, Location—Innovation


When one thinks of important medical device innovators, large multinational companies such as Abbott, Boston Scientific, GE Healthcare, Johnson & Johnson, Medtronic, and Siemens all come to mind. But identifying the regional sources of the innovations that drive these companies' growth can be a complicated matter.

Many of the medtech industry's largest companies play significant roles in developing and supporting centers of innovation, both within the United States and abroad. But universities, incubators, government agencies, and start-up companies also play measurable roles in defining the innovation capacity of a particular region. And then there is the matter of innovation quality—whether some locations are superior in terms of generating influential new technologies.

Interesting information about the regional sources of medical device innovation has been developed for this article by the Patent Board (Chicago), a leading patent advisory firm. Patent activity is one of the best formal measures of innovation. Using its proprietary data, tools, analytics, and technology, the Patent Board has studied recent medtech patents in order to identify the key domestic centers of medical device innovation as well as the degree of global participation in generating U.S. patents.

Although the market for medical devices is growing internationally, domestic invention continues to not only thrive but dominate global market share. Of the top 25 global public medical device companies ranked by product revenue, 16 are U.S. based and account for 72% of global profits.1

While domestic medical device patenting is slowing down overall, the United States remains the largest innovator of medical device technologies, and U.S. companies both large and small are still aggressively seeking to develop and protect intellectual property. Non-American participation in U.S. device innovation is also strong; specifically, the proportion of foreign inventors named on U.S. medical device patents has been consistent over the past six years.

This article presents an analysis based primarily on selected patent data from 2007 U.S.-issued inventions in the medical device industry as defined by the Patent Board's industry mapping and corporate unification tools. Inventor addresses given in patents served as a proxy for innovation location. Rather than relying on a count of unique patents as the basis for determining regional innovation productivity, the analysis approached the issue from the perspective of inventor contributions—that is, total numbers of inventors within a given city or core-based statistical area (CBSA) whose names appear among all patents issued during a given time period.

Domestic Hot Spots: Patent Quantity

Perhaps not surprisingly, Minneapolis–St. Paul–Bloomington, MN (including neighboring Wisconsin), turns out to be the top CBSA for patent authorship in 2007 within the medical device category. Both Medtronic Inc. (Minneapolis), the most productive medical device company for 2007 in terms of patent activity, and Boston Scientific Corp. (Natick, MA) have a large regional presence in Minnesota. (Boston Scientific has branches in Maple Grove, Plymouth, and St. Paul.) St. Jude Medical and 3M (both in St. Paul, MN) also have a significant presence in this region. This combination of corporate medical device powerhouses seats this area of the country comfortably in the number one spot for both issued patents and published applications, indicating that there is a significant brain trust in the region (see Table I).

Core-Based Statistical Area
Inventors (no.)
Minneapolis–St.Paul–Bloomington, MN; WI
Los Angeles–Long Beach–Santa Ana, CA
San Francisco–Oakland–Fremont, CA
San Jose–Sunnyvale–Santa Clara, CA
Boston–Cambridge–Quincy, MA; NH
New York–Northern New Jersey–Long Island, NY;    NJ–PA
San Diego–Carlsbad–San Marcos, CA
Chicago–Naperville–Joliet, IL; IN–WI
Miami–Ft. Lauderdale–Miami Beach, FL
Seattle–Tacoma–Bellevue, WA
Table I. The core-based statistical areas (CBSAs) with the greatest inventor participation in U.S. medical device patenting in 2007, ranked by inventor count. Source: The Patent Board.

As Table I shows, four of the top 10 CBSAs are in California. Leading patent creators with operations in these areas include St. Jude Medical, Abbott Laboratories (Abbott Park, IL), and Cymer Inc. (San Diego).

The future of the Minneapolis–St. Paul region is extremely promising not only because of the companies situated there, but also because the University of Minnesota (Minneapolis), which ranks ninth for enterprise patent volume in this area, is taking more-assertive measures to pursue university-based spin-offs through its office of technology commercialization. According to Doug Johnson and Dick Sommerstad from the University of Minnesota office of business development, contributions from past spin-offs have been quantified. Those enterprises accounted for as much as $33 billion between 1980 and 1999 and produced upwards of 280,000 jobs during that period.2 The impact of future spin-offs will likely exceed these numbers now that commercialization of the university's technology developments has been prioritized.

While it might have been expected that the home of Medtronic tops the list of regions with high inventor participation in U.S. medical device patent generation, it could be surprising that four of the top 10 CBSAs are in California. Los Angeles–Long Beach–Santa Ana is ranked second, San Francisco–Oakland–Fremont third, San Jose–Sunnyvale–Santa Clara fourth, and San Diego–Carlsbad–San Marcos seventh. Leading patent creators with operations in these areas include St. Jude Medical, Abbott Laboratories (Abbott Park, IL), and Cymer Inc. (San Diego).

The San Diego–Carlsbad–San Marcos area stands out in that 48% of its U.S.-issued patents for 2007 belong to smaller patenting organizations rather than what the Patent Board calls unified companies (those with a minimum of 45 U.S.-issued patents over the preceding 60 months, typically well established large corporations). This may indicate that the area is a potential hotbed of newly emerging companies within the medical device industry. Nationally, only 31% of medical device patents belong to smaller patenting companies. This number has remained constant at around 30% from 2002 through 2007.

Those four California CBSAs are in the top 10 also for patent applications, another measure of inventor productivity. Therefore, it appears that they will continue to be centers for medical device innovation in the near future. It also explains, in part, why California is the U.S. state most productive of new medical device technology in terms of patents issued for 2007. Minnesota, Massachusetts, New York, and Florida round out the top five for that metric. The five most innovation-productive states in terms of patent applications published within the past year are the same except that Ohio replaces Florida, likely because of the presence there of Hill-Rom Holdings Inc. (Batesville, IN) and Johnson & Johnson (J&J; New Brunswick, NJ).

So far, this article has primarily mentioned corporations as the top patenting organizations within the CBSAs discussed. That is because, while noncorporate entities such as universities, government agencies, and nonprofit research institutes do hold significant patents, the numbers are far below those of their corporate counterparts. Universities account for approximately 3% of U.S. medical device patents issued in 2007, while government and nonprofit research institutes represent approximately 0.5%.

It is interesting that the top CBSAs are home to major medical device–patenting universities and research institutes. The University of Minnesota, the 10-campus University of California system (headquartered in Oakland, CA), Stanford University (Palo Alto, CA), and the Alfred E. Mann Foundation (Santa Clarita, CA), as well as Harvard University (Cambridge, MA) and Boston University, are prominent institutions located within the top-ranked CBSAs. The sixth-ranked New York–Northern New Jersey–Long Island CBSA contains no fewer than 10 universities, including the State University of New York, Columbia University (New York City), and Cornell University (Ithaca, NY). Among the CBSAs in Table I, this region is the second most productive of innovation in terms of inventor contributions from universities and research institutes, behind only the Los Angeles–Long Beach–Santa Ana, CA, area. Along with corporate industry players, the presence of these organizations and the spin-offs they help to create undoubtedly contribute to the ferment of innovation within these top-ranked regions.

Domestic Hot Spots: Patent Quality

The Patent Board tracks and analyzes the innovation quality, movement, and industry impact of patent assets, using a number of indicators. Two indicators that speak to the overall assessment of patent quality are current impact and science linkage.

Current Impact. The current impact indicator measures the broader significance of a company's patent portfolio by examining the impact its patents have across the industry in a given year (see Table II). The current impact score indicates the extent to which a company's patents serve as a foundation for industry patents and technologies developed subsequently.

Core-Based Statistical Area
Current Impact Score
Boulder, CO
Santa Cruz–Watsonville, CA
Columbus, OH
San Jose–Sunnyvale–Santa Clara, CA
San Francisco–Oakland–Fremont, CA
Denver–Aurora, CO
Minneapolis–St. Paul–Bloomington, MN; WI
Austin–Round Rock, TX
Pittsburgh, PA
Kansas City, MO; KS
Table II. The top 10 CBSAs by current impact. This indicator is a measure of the strength of an organization's—and collectively a region's—influence on worldwide technology development through its patents being a foundation for other patents and technologies. Source: The Patent Board.

By this measure, Boulder, CO, replaces Minneapolis–St. Paul–Bloomington, MN, as the top-ranked CBSA, with Boulder's recent medical device patents having the most significant impact on 2007-issued patents. Minneapolis came in seventh place as measured by documented influence of patent portfolios held by companies in each region.

The major industry player in the Boulder area is Covidien Ltd., which is formally headquartered in Hamilton, Bermuda. Covidien accounts for the majority of the region's high-quality patents. Its most fertile technology (in the sense of inspiring other patented work) pertains to electrosurgical apparatus and devices that seal blood vessels, among other applications. Covidien is also a major presence in fifth-ranked San Francisco-Oakland-Fremont, CA, as well.

Industry newcomer Otologics LLC (Boulder, CO), a manufacturer of fully implantable hearing devices, has recently picked up the pace in patenting and may be a factor in terms of future patent quality for this Colorado CBSA.

The Santa Cruz–Watsonville, CA, area is ranked second overall for patent quality. Major corporate contributors to this ranking include Abbott Laboratories and St. Jude Medical. Interestingly, Abbott's most influential endovascular technology developed in this region once belonged to former competitor Guidant Corp. By acquiring Guidant's endovascular business, Abbott was able not only to diversify its portfolio but also to incorporate some very strong, high-quality technology.

Abbott's acquisition strategies and procurement of strong technologies also contribute to the high ranking of the Austin–Round Rock, TX, region, which is in the top 10 for two patent quality indicators. The Austin-centered CBSA ranks eighth overall for patent quality (current impact) and fifth for science linkage (explained in the next section). Abbott Spine (Austin, TX), formerly Spinal Concepts Inc., was acquired by Abbott in 2003 and has several of the region's highest-quality patents. Abbott Diabetes Care (Alameda, CA) also holds highly influential patents that were developed in this region, thanks to its 2004 acquisition of Therasense. The Therasense portfolio brought high-quality technologies for blood glucose self-monitoring systems into the Abbott portfolio. The Abbott Diabetes Care patents, which are more numerous than those that belong to Abbott Spine, have exhibited a high degree of influence among recently issued patents, but also show extremely strong science linkage.

The Minneapolis–St. Paul–Bloomington, MN, CBSA region, the patent quantity leader, ranks seventh for patent quality in the analysis for 2007. Two of Boston Scientific's subsidiaries—Cardiac Pacemakers (St. Paul, MN) and SciMed Life Systems (Maple Grove, MN)—and Medtronic all have high-quality patents that boost this region's rating. A younger company, Acorn Cardiovascular (St. Paul, MN), with technologies for cardiac support devices, is also generating high-quality patents in this region. Acorn's patented work is highly influential among direct competitors in this field.

Science Linkage. Science linkage is an indicator of the degree to which the patents generated in a particular region represent technological innovation building off of objective, peer-reviewed scientific research. A higher score indicates that the company's technology is more seminal or closer to the cutting-edge than those of its competitors. Allentown–Bethlehem–Easton, PA (with neighboring New Jersey), ranks as the top CBSA under this quality metric. J&J's subsidiary Cordis Endovascular (Warren, NJ), which develops products to treat various circulatory diseases, accounts for many of the inventions from this region most closely aligned with new science.

Newly emerging medical device companies such as Glucolight Corp. (Bethlehem, PA) also have strong technologies rooted in scientific research. Glucolight's optical coherence tomography provides a more sophisticated means of continuous and noninvasive blood glucose monitoring that may be crucial for successfully managing intensive-care patients.

The second-strongest CBSA for science linkage is the Washington–Arlington–Alexandria, DC–VA–MD area. Here, government agencies appear among the top patenting organizations, as the U.S. Department of Health and Human Services, U.S. Navy, and U.S. Army are among the most prolific patent generators in this region. They possess patents reflecting a strong basis in scientific research. Among academic institutions in the region, Johns Hopkins University (Baltimore) contributes most prominently to the area's high science linkage rating, being the second most prolific patenting organization in the CBSA.

In addition to mainstays such as Medtronic, emerging companies such as NeuroVista Corp. (Seattle) are also performing well by this indicator. NeuroVista, which is pioneering implantable neurotechnologies for the management and treatment of epilepsy, has three of the five patents top-rated for science linkage.

U.S. Patents, Global Authorship

Regional patent productivity can be examined from the perspective of major cities as well as CBSAs. Using inventor addresses as a proxy for corporate locale results in the top city listed on U.S. medical device patents being in fact not a U.S. city at all. Although the number of patent authors living in U.S. cities exceeds that of foreign-resident inventors, Tokyo is actually the inventor city that is most prolific in terms of authors named on 2007 U.S. medical device patents. San Jose and San Diego follow in second and third place. Tokyo would place eighth among CBSAs if it were included in that ranking.

The majority of 2007 U.S.-issued patents naming Tokyo-resident inventors belong to Japanese-based companies such as Topcon Corp., Olympus Corp., Hoya Corp., and Hitachi Ltd., as might be expected. However, the company that has the greatest number of Tokyo medical device inventors is U.S.-based General Electric (GE; Fairfield, CT). A multinational conglomerate such as GE or Hitachi can harness global resources to enhance innovation.

An issue for consideration suggested by Tokyo's top-city standing is whether U.S. medical device patents are increasingly being authored by foreign inventors and organizations. This does not appear to be the case. If it is so, then the phenomenon is taking place slowly. In 2007, the percentage of U.S.-issued medical device patents naming exclusively foreign inventors was 31.5%. While that represents a significant portion of the industry's patents, the number has risen only 1% since 2002. Incidentally, 3.9% of U.S. medical device patents issued in 2007 list U.S. and foreign inventors working collaboratively.

After Japan, Germany and France are contributing most significantly to the work resulting in U.S. medical device patents (see Table III). Their inventor contributions to U.S. patents issued from 2002 through 2007—that is, the portion of inventors named on the patents who resided in those countries—were 9%, 6%, and 2%, respectively.

Inventors (no.)
United Kingdom
The Netherlands
Table III. The top 10 countries with the greatest inventor participation in U.S. medical device patent authorship, as determined from utility patents issued in 2007. Source: The Patent Board.

The situation is a little different at the top of the list of countries whose inventors published patent applications during the period of this study. Israel replaces France as the third-highest-contributing country. Israel has become a global life sciences and medical device industry hotbed. The country is home to approximately 900 established life sciences companies, and at least 50 or 60 new ones are formed each year. According to Invest in Israel, more than one-third of Israeli life sciences start-ups already generate revenues.3


Most innovation activity in the medical device industry continues to take place within the United States. As evidenced by domestic patent productivity, that technological creativity is distributed throughout the nation. While some regions, such as the Minneapolis–St. Paul–Blooming­ton, MN/WI and Los Angeles–San Francisco–San Jose areas are more productive overall, others, such as Boulder, CO, and Allentown–Bethlehem–Easton, PA/NJ, rank high in measures of patent quality.

Centers of innovation tend to be anchored by strong universities and research institutions, which are not only patenting in their own right but also collaborating with companies. The Association of University Technology Managers has noted that the number of new spin-offs from academic institutions rose from 494 in 2001 to 628 in 2005, a 27% increase. The 10-year increase through that date was 181%. Many of these innovating enterprises operate in the biomedical field.4,5

Other nonprofit research institutions have also been active. For instance, the Cleveland Clinic Foundation (Cleveland), through its technology commercialization arm CCF Innovations, has spun off approximately two dozen companies since 2001. Products based on CCF Innovations' intellectual property have generated nearly $400 million in sales and will undoubtedly continue to stimulate Northeastern Ohio's economy for years to come.

One CCF Innovations spin-off is Zin Medical (Cleveland) established in 2006 and jointly owned by Zin Technologies Inc. and the Cleveland Clinic. It has developed a wireless biometric monitoring device for use in aerospace, military, and civilian terrestrial settings. Zin Medical exemplifies the industry advancement potential of regional collaborative efforts, which will surely be a factor in driving future research and patenting activities in the nation's innovation centers.


  1. "Business News: Medtech's Top-25 Firms Post Strong Revenue Gains in 2007," MX 8, no. 3 (2008): 12-14.
  2. D Johnson and D Sommerstad, "Industry Academic Partnerships: The New Corporate Research and Development" [online briefing] (St. Paul: MN: University of Minnesota, Office of Business Development, 2006 [accessed 13 August 2008]); available from Internet:
  3. "Invest in Israel, Life Sciencs [sic] in Israel" [home page online] (Jerusalem: Invest in Israel, 2008 [accessed 13 August 2008]): available from Internet:
  4. TJ Sheeran, "New Companies Cash In on Medical Innovations" [online] (Cleveland: Associated Press, 2007 [accessed 13 August 2008]): available from Internet:
  5. Association of University Technology Managers, AUTM U.S. Licensing Survey, FY 2005: A Survey Summary of Technology Licensing (and Related) Performance for U.S. Academic and Nonprofit Institutions and Technology Investment Firms, ed. D Bostrom and R Tieckelmann (Northbrook, IL: Association of University Technology Managers, 2007 [accessed 14 August 2008]): available from Internet:

Paris Kucharski is an advisory services associate, and Scott Oldach is president, at the Patent Board (Chicago).

Copyright ©2008 MX

In Memory, Rhall E. Pope


MX magazine, the medical device industry, and especially the insulin pumping world, lost a trusted advisor and gifted contributor with the recent passing of Rhall E. Pope, PhD. A mentor to many device design teams, Pope moved from aerospace to medical when he joined Smiths Medical (St. Paul, MN) as vice president of research and development in 1998.

Pope enjoyed talking to customers and was truly interested in what they had to say. His attitude toward customers inspired the teams he led to build better products. He led the team that took Smiths into the new business area of insulin delivery technologies. Rather than making incremental improvements, he immersed his team in the issues faced by many people with diabetes, and led the company to create a 'smart pump' that represented a radical departure from previous products.


As Smiths grew by adding new businesses, so also did Pope's responsibilities. He continued to inspire the teams he led, encourag­ing a user-centric approach to product development in a variety of other areas. He had a keen interest in diabetes research and most recently served on the board of directors of the Minnesota chapter of the Juvenile Diabetes Research Foundation.

Pope earned a BS from Duquesne University and an MS and PhD from Purdue University. He served on FDA's science review board and was a member of the University of Minnesota Biomedical Engineering Institute's industry advis­ory board.

Pope joined the MX editorial advisory board in 2006. In conjunction with this duty, he was also a member of the steering committee for the magazine's executive-level conference, BIOMEDevice Forum.

When he moved into the device industry, Pope told colleagues that he wanted to end his career helping people have better lives. People who worked with him observe that he accomplished this goal.

Copyright ©2008 MX

Medtech Industry Asserts Value of 510(k) Classification


Under the provisions of the FDA Amendments Act of 2007(FDAAA), the Government Accountability Office (GAO; Washington, DC) is scheduled to issue a report to Congress on the "appropriate use" of FDA's 510(k) premarket notification process for the evaluation and approval of medical devices. The provision calling for such a report grew out of congressional hearings during the summer of 2007, before the bill was approved and signed into law by President Bush last September.

Several consumer groups, including Public Citizen (Washington, DC) and the National Research Center for Women and Families (NRC; Washington, DC), questioned the wisdom and validity of the 'substantially equivalent' predicate device concept, which is a core tenet of the 510(k) process.

Testifying before the health subcommittee of the House Committee on Energy and Commerce, in July 2007, NRC president Diana Zuckerman, PhD, called upon the legislators to seek a detailed analysis of how devices are evaluated and approved under the 510(k) protocol.

"Although the standard of 'substantially equivalent' for devices sounds almost like the standard for a generic drug, the reality is completely different," Zuckerman testified. "Many medical devices approved by the FDA through the 510(k) process are not like any medical devices already on the market, and are instead made of different materials, used for different purposes, use a different technology, or are otherwise 'new and different' rather than slightly improved."

Zuckerman and spokespersons for other consumer and public interest groups would like to see more-rigorous evaluation of all medical devices, which would typically require greater use of clinical trials similar to medical products that are subject to FDA's premarket approval (PMA) process.

The 510(k) protocol was initially codified in the Medical Device Amendments of 1976, which significantly strengthened FDA's authority to regulate medical devices. The protocol has continued to evolve through agency guidance documents and legislation. The concept of substantial equivalence was acknowledged in the 1976 legislation and subsequently became codified in the Safe Medical Devices Act of 1990.

Concerned that FDA's 510(k) protocol is misunderstood, AdvaMed issued a report titled The 510(k) Process: The Key to Effective Device Regulation earlier this month. The organization described the report as a white paper that "outlines the history and evolution of FDA's 510(k) program from its inception with the Medical Device Amendments of 1976 to the present day, explains why the program is an appropriate and effective regulatory approach for the vast majority of medical devices, and dispels some common misconceptions about the program."

AdvaMed says that 90% of all medical devices are evaluated and approved through the 510(k) process.

Mark Leahey, executive director of the Medical Device Manufacturers Association (MDMA; Washington, DC), said, "We vigorously support the 510(k) protocol. We believe it provides both a solid framework and flexibility for evaluating particular kinds of medical devices. FDA already has—and frequently exercises—its authority to require additional information and action steps before a device is approved via the 510(k) protocol. Of course, FDA always has the option of requiring a manufacturer to submit the device under the PMA standard."

The GAO report will review both 510(k) and PMA data over the five-year period of 2003-2007. In preparing the report, the agency met with representatives from AdvaMed, MDMA, FDA, and vari­ous other stakeholders. Although the report is due September 27, a GAO spokesperson has indicated that a written document will not be available at that time, but the agency will brief both the House Energy and Commerce Committee and Senate Health, Education, Labor and Pensions Committee on the salient findings.