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Medical Product Manufacturing News, March/April 2015

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M e d i c a l P r o d u c t M a n u f a c t u r i n g n e w s q m e d . c o m / m p m n 6 M a r c h / a P r i l 2 0 1 5 need to KnoW a university of Michigan spin-off has found a more durable way to enhance electrodes with conductive polymer coatings. the development could further enable the miniaturization of implantable medical devices. an undisclosed medical device company is seeking a ce mark this year for a novel electrophysiology (eP) catheter that uses amplicoat from Biotectix (ann arbor, Mi: www. biotectix.com), with plans to win fda approval soon after, says the company's cofounder and engineering director Jeff hendricks. other companies have their own applications in the works. Biotectix has discovered that amplicoat- coated electrodes can be up to 80% smaller than traditional metal electrodes that measure several millimeters across and still deliver the same amount of energy, hendricks says. "that opens up whole new possibilities for designing a device, for being able to reduce the cost by reducing precious metals. it also opens up whole new fabrication methods [such as flexible circuits]." the technology allows for higher numbers of electrodes for a given-sized lead or device and provides greater tissue-sensing resolution. there is more localized stimulation control, higher signal fidelity, lower power requirements, and reduced stimulation thresholds, according to the company. smaller electrodes also reduce the need for gold and other precious metals. "it's much more similar to the tissue in our body than what's currently available," hendricks says. "it's softer. it transfers charge both electrically and ionically." think of catheter-based probes that are able to fit into much smaller areas of the body and neuromodulation and pacing devices delivering much more precise charges. "it allows you to target the response you're looking for without producing a lot of unwanted side effects," hendricks comments. he also thinks that the efficiencies delivered by amplicoat could further reduce battery sizes for leadless pacemakers. Biotectix's roots go back to the past decade. hendricks, then a university of Michigan graduate student, helped david Martin, then a Michigan professor (now a university of delaware professor and Biotectix's chief scientific officer), with his work on medical applications for Poly(3,4– ethylenedioxythiophene) (Pedot). Pedot, which has been used as a static reducer in electronics packaging since the late 1990s, is the material used to make amplicoat. their efforts resulted in Biotectix, which was formed in 2007 through a joint venture between the university of Michigan and allied Minds, a Boston-based science and technology development and commercialization company. Biotectix's major challenge in recent years was how to make Pedot durable enough for the rigorous environment inside the human body. "we spent a lot of time working on different formulations and being able to demonstrate the coating can demonstrate, say, 10 years of pacing pulses and other environmental impacts of being in a moving human heart for 10 years. we went through several formulations of the coating until we struck on this one," hendricks says. Pedot, which is positively charged, generally has polystyrene sulfonate paired with it as its negative counter ion in industrial applications. Martin, hendricks, and other researchers eventually discovered that surModics inc.'s Photolink technology for hydrophilic coatings could provide the durability they were looking for as a substitute for polystyrene sulfonate. Biotectix has conducted accelerated aging tests in heated saline solutions. it has cranked up pacemaker pulses to a thousand pacing pulses per second to demonstrate that the coating could last for at least 10 years on a heart-pacing electrode. —chris newmarker How a new coating could enable Tinier electronics in the Body Wearable for the Tongue Tackles Traumatic Brain Injury here's a wearable unlike any you have ever heard of before: a device that connects to the tongue to stimulate the cranial nerves to help treat traumatic brain injury. the device, which is in development by Helius medical Technologies (newtown, Pa; www. heliusmedical.com) and Ximedica (Providence, ri; www.ximedica.com), was inspired by the work of Paul Bach-y-rita, an american neuroscientist who was a pioneer in the field of brain plasticity. in 1958, Bach-y-rita's father had suffered a debilitating stroke. convinced that through exercise, the brain could recover from mental deficits, the neuroscientist set up testing his theories to help his father. "so he nursed his father back to health by having him do excruciating exercise for a long period of time," says Phil deschamps, ceo of helius Medical technologies. over time, the exercises succeeded in helping his father recover most of his functions. the technology works according to the same principle. exercise, or in this case exercise conjoined with neural stimulation, can work as a catalyst to cause the brain to reorganize itself to overcome deficits caused by disease or trauma. to understand the technology, think of someone who has had a stroke. "let's say that the part of the brain that dies [in the stroke patient] is the part that moves the right arm," deschamps says. the neural impulses that are coming from the arm travelling up the spine no longer have a destination in the brain." the device supplements the neural impulse—in this case, from the arm—with 27 million impulses that are delivered straight from the tongue directly to the learning centers of the brain. this essentially tricks the brain into thinking the arm is moving. the strength of the signal coaxes the brain into remodelling itself to try to find a new pathway for that movement, which ultimately helps it overcome mental deficits caused by trauma. so why is the company using the tongue as a pathway? "this was the genius of Paul Bach- y-rita, who helped develop this," deschamps remarks. "99% of people think of the tongue as an apparatus for taste. But when you think about it from an evolutionary standpoint, the tongue from zero to six months is your primary learning mechanism." everything a baby grabs and puts into their mouths, the tongue is used to determine whether it is hard, soft, desirable, or undesirable. the tongue is tied to the learning centers of the brain—in particular to the pons—part of the brain stem. scientists eventually had the idea to communicate with the learning centers of the brain via the tongue and to obtain patent protection for the concept. "now, the company owns all of the patents that have to do with stimulating the tongue to combine with physical exercise to produce a therapeutic outcome," deschamps notes. the bulk of the early research attempted to find an interface that would work with the tongue to pass current through it to produce the right kind of neural impulses. the main goal was to try and produce neural impulses traveling from the tongue to the brain that mimic motor impulses that come up through the spine. "a large part of the original research was trying to refine the stimulation pattern so we would be able to produce that through the tongue," deschamps explains. "with respect to the device design element, we had a good head start because the scientist who developed what i call the 'lab widget' produced the right waveform, frequency, and electrical stimulation to produce the desired outcome," deschamps recounts. when helius began to collaborate with Ximedica, the company was focused on taking the basic lab technology and evolving it into a more sophisticated design that would ultimately pass regulatory muster. "our goal was to make it as true to the original stimulation pattern as possible," he says. "the major design issues were around trying to make sure the form was improved to try to help patients use the device more simply and to reproduce the original waveform as much as humanly possible." this required making the device not only simple to use but also compatible with users' normal exercise routines and lifestyles. "Quite frankly, it is a counterintuitive design," deschamps says. "the original device was something that fit entirely in your mouth, and all of the pulse generation was sitting right outside of the mouth." this made it somewhat difficult for the user to exercise without clamping down on the device to hold it in the mouth—owing to the weight of the early prototype. the designs that Ximedica came up with focused on using the neck and shoulders to support the weight of the device. the design makes use of a tongue array linked to a cable. "it is now much more self-contained and easier for patients to be able to hold in their mouth, allowing them to do the exercise more easily," deschamps concludes. —Brian Buntz a coated cardiac eP catheter used in a study involving Biotectix's amplicoat.

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