Sensors in Design 2012 was opened March 28 at the San Jose McEnery Convention Center, in conjunction with Design West, an agglomeration of seven individual design-related symposia with a common exhibition floor. This is my first time attending this meeting, but I overheard several other folks remarking that it’s good to see attendance is back up after a slump the past two years.
The sensors symposium opened with a panel discussion on the future of MEMS. Rob O’Reilly of Analog Devices, Dave Rothenberg of Movea, and Stephen Whalley of Intel comprised the panel, moderated by Alissa Fitzgerald of AM Fitzgerald & Associates. Intel is a MEMS user and systems designer but not a manufacturer, noting that more standardization is required for greater scalability and a robust foundry infrastructure. Healthcare opportunities range from smart phone consumer apps to implantable devices, and will take greater advantage of printable electronics for end device integration. MEMS accelerometers and gyroscopes have been around for 30-40 years, but did not proliferate widely until the price dropped below $5. Other devices that may be poised for their own volume explosion are being hindered by their dependence on expensive TSV solutions for system integration; other system integration architectures must be developed. Whalley opined gyroscopes need to drop below $1 for broader system implementation, but O’Reilly said that this will never happen. There was also some lively misalignments as to whether component margins were adequate. Medical device realms are broadly divided into wearable and implantable, or by clinical devices and lifestyle devices. Either way, FDA approvals will throttle one group severely, while those not requiring such approval will lead the market growth. O’Reilly noted that the MEMS manufacturers are adapting SEMI and JEDEC standards to their industry, but they don’t happen to be MEMS-specific standards. The entry of CMOS foundries like TSMC into MEMS production will likely accelerate the broader adoption of standards. Pricing is an incentive for more implementation of printed electronics, but the requisite manufacturing repeatability is still lacking for many applications. The oil and gas industry has the potential to drive innovation with healthier margins, and without the bureaucratic inhibitors found in medical applications. Energy harvesting MEMS are more likely to prosper with thermoelectric Peltier devices than with piezoelectric vibration harvesters, due to the power density opportunity available.
Nancy Dougherty of Proteus Biomed talked about mindfulness pills for the quantified self. The quantified self is a conceptual platform for self-monitoring of health-related factors based on the premise that you have to be able to measure it before you can fix it. Our national healthcare system is based on population statistics, not on individual metrics. This technology-enabled movement can help change that. Proteus itself designs digestible electronics that can be embedded in pills and report biometric data to a receiver patch worn on the torso, including the identity of the pill and the time it was ingested. An interesting experiment with the use of placebo pills to effect real change in mood can be found at http://theengineeress.com/mindfulness. The pill electronics are powered by opposing calcium and magnesium electrodes that are activated by stomach fluids.
Peter Himes of Silex Microsystems (self-identified as the world’s largest MEMS foundry) gave several examples of MEMS implementation for biomedical applications. MEMS are particular adept for applications in which only very tiny analyte samples are available, though they can also provide significant cost advantages where MEMS functionality can displace bench top equipment alternatives. Microfluidics technology is particularly prevalent in this arena, though devices like micro defibrillators and micro needle patches for drug delivery and bodily fluid sampling also play a large role here.
Alissa Fitzgerald of AM Fitzgerald and Associates described more medical research applications of MEMS technology. Blood pressure cuffs in doctors’ offices have used MEMS pressure sensors since the 1980s; who knew? Contact lenses with a strain sensor to measure intraocular pressure constantly and in real time (made by Sensimed) may displace the need for annual glaucoma testing. Second Sight is commercializing a prosthetic retina that can provide a degree of optical nerve stimulation in lieu of natural sight to circumvent some forms of blindness. The introduction of flexible and biodegradable materials is expanding the repertoire of MEMS tools well beyond its traditional silicon origins.
Jamshid Avloni of Eeonyx Corporation took a look at innovations and applications in interactive fabric sensor technology. Taken to its extreme, this means electronic clothing. The underlying technology is conductive textiles, with coatings that are robust enough to stand up to conventional laundering. Fabric sensors have several advantages over thin film sensors, not the least of which are comfort and invisibility, not in the Harry Potter magic cloak sense but in the sense of presenting nothing foreign or unfamiliar to the user. I’ve already seen a commercial implementation of these materials in a shoe store, where you can step on a platform and get a precise pressure map of your footstep to assist with sizing shoes or designing inserts. Pressure sensing gloves have been used in applications ranging from golf and piano lessons to sniper training. A clean version of paintball has been developed, using rubber balls and impact sensing vests in place of paint, making cleanup a non-issue. A sample of coated material felt no different from conventional clothing fabric. Resistivities of a fabric sample pack ranged from 15 Ω/square to 104Ω/square.
See http://www.eksobionics.com for an example of a biomechanical exoskeleton that makes extensive use of these materials to enable paralyzed people to walk.