by Randy Frank, Contributing Editor
Portable wireless healthcare products are driving the development of many new sensor products
Your car continuously monitors its critical systems. Your cellphone makes numerous measurements constantly. But what about the most sophisticated system there is—you? Historically, measurements were only taken when there was a health problem or during a routine medical checkup. Today, with wellbeing becoming an important focus, more and more measurements are made on a more frequent, some would say real-time, basis.
Medical and healthcare applications continue to challenge sensor suppliers, especially in an untethered world. Cloud-based applications have expanded and enhanced the capability that existing sensors provide. Sensor suppliers are up for the challenge and their customers are poised to take advantage of the newest technology approaches. Several measurements are required to provide an accurate indication of the patient’s health and wellbeing, including pressure, heart rhythm, temperature, motion, glucose, pulse oximetry and more.
MEMS in medicine
Diagnostics and drug research are important medical areas for the Tronics Group. The company has a couple of techniques that are used in microarrays for DNA analysis. It also performs wafer foundry services for several medical applications.
“Point of care diagnosis is doing blood tests and similar things in a doctor’s office or a hospital environment,” said Brian Stephenson, COO, Dallas Operations of Tronics Group. “They are leveraging a lot of advances in MEMS that have happened over the past few years.”
The timing finally seems to be right for microelectromechanical systems (MEMS) sensors in more medical applications.
“Application awareness and some pioneering companies have introduced products and are now starting to be successful, so of course that draws more people in to see what else they can do,” said Stephenson.
It is difficult to pinpoint a specific area that has caused the uptick in medical interest in MEMS.
“A bunch of small improvements have brought us into the picture in the last five years,” said Herve Borrel, president and CEO, Tronics North America. The use of materials that are not commonly used in silicon foundries and flexibility in a more specialized wafer-fabricator, like Tronics, also attracts innovative customers.
“Where we expect to see rapid expansion over the next few years is in the diagnostics and research side applying MEMS in those areas,” said Stephenson.
Flexible/stretchable sensors
Printable, flexible sensors are poised to play an important role in healthcare and other applications. According to IDTechEx’s Dr. Guillaume Chansin, “The market for printed sensors will increase by more than $1 billion by 2020.” Today, disposable glucose test strips have the lion’s share of existing printed sensors, but new materials will open the way for other measurements.
While not printable, at least in the conventional sense, MC10 uses special materials and processing techniques to produce soft and elastic sensors and associated circuitry. The approach has created a new class of biointegrated devices with attractive possibilities for mapping electrical, mechanical, chemical and thermal properties at the cellular level.
One of the first companies to take advantage of the design approach is Reebok. The CHECKLIGHT, a soft skullcap designed by the company, embeds MC10’s conformal electronics platform. Worn with or without a helmet, the instrumented cap provides an indication of impact severity.
“The CHECKLIGHT couples sensors directly to the head to accurately detect the force of impact that the head, not a helmet, receives,” said Isaiah Kacyvenski, head of MC10’s Sports Business division. “Removing the subjective nature of self-reporting serious head impacts starts a conversation and an assessment that far too often isn’t initiated.”
MC10’s Biostamp takes flexibility one step further. The sensing sticker stretches, flexes and moves with the body and can measure physiological functions including data from the brain, muscles, heartbeat, body temperature, hydration levels, respiration, motion and blood oxygenation.
“The MC10 Biostamp bridges the gap between the rigid, boxy nature of contemporary electronics and the soft, sensitive form of the human body,” said Milan Raj, senior electrical engineer at MC10. “This will enable a variety of digital health applications and help users quantify their biometrics with devices that are inconspicuous and mechanically transparent.”
Wearable sensors
Wearable medical sensors do not have to be flexible. Zephyr’s Physical Status Monitoring (PSM) solutions address physiological and biomechanical measurements with a rigid BioPatch that houses sensors and complementary circuitry. Measurements include:
• heart rate
• interbeat (R-R) Interval
• respiration rate
• ECG
• activity level
• position
• posture
The patient-worn BioPatch wirelessly transmits vital signs to the company’s ZephyrLIFE monitoring station using ECHO Mesh Radio for hospital applications and a ZephyrLIFE Portal with the Zephyr HealthHub or 2net device for home applications. Additional sensors can include blood pressure, glucose, weight and SpO2.
Sleep like a baby
Wearable technology has an exciting future, but you don’t want to wear it to bed. BAM Labs (BAM: Body and Motion) found a solution for data collection and analysis with its Touch-free Life Care (TLC) smart bed system. The TLC System sensor mat embeds a Freescale pressure sensor to collect a variety of data. Located under the mattress, the touch-free sensor continuously detects trends in heart rate and breathing rate, motion and presence. Proprietary algorithms in the system process the raw data and the system exchanges measurements with the sensor and BAM Labs’ cloud platform for caregiver and consumer use. This information is conveyed to computer or mobile devices to analyze sleep patterns.
At CES 2014, Sleep Number introduced its x12 bed with SleepIQ (touch-free) technology developed by Sleep Number and BAM Labs. The SleepIQ system monitors presence in bed, average breathing rate, movement and average heart rate.
Control insulin delivery
Using its Enlite glucose sensor, Medtronic’s MiniMed 530G with Enlite system is the first artificial pancreas system in the United States that can automatically stop insulin delivery when glucose values reach a preset level—and when the patient does not respond to the system’s Threshold Suspend alarm. While 69% smaller than its predecessor, the sensor delivers a 31% improvement in overall accuracy.
The system’s Threshold Suspend function automatically stops the delivery of insulin if the sensor detects glucose levels above a threshold that can be set by a healthcare provider between 60 to 90 mg/dL. At the threshold value, the system first alerts the wearer with an alarm. If the individual does not react, the system suspends insulin delivery for two hours, but it can be resumed at any time.
Traditional measurement, new sensor
In spite of all the new medical sensing applications, many well-established measurements continue to generate new products. For example, based on proprietary MEMS technology, Merit Sensors introduced a new blood pressure sensor product, the BP Series, with high accuracy invasive blood pressure measurements being one of its targeted applications.
Measuring 8.1 x 10.5 mm with a weight of 2 g, the BP Series exceeds the requirements of the industry standard American Association of Medical Instrumentation (AAMI) BP22 standard. The sensors operate in a pressure range of -30 to 300 mm Hg over the temperature range of 15 to 40° C.
As a part of Merit Medical Systems, Merit Sensor has evaluated application subtleties of blood pressure sensors in real-life medical situations, as well as the potential failure mechanisms caused by inappropriate use.
“This knowledge is incorporated into the design of the BP Series to exceed critical specifications like burst pressure—the BP Series typically allows for ten times the accidental overpressure or extreme shock application to blood pressure transducers,” said Rick Russell, president of Merit Sensor.
Take a deep breath
Chris Stiffler, founder and CEO of Vicinity Health, had a severe asthma attack early in 2014 that inspired him to develop a new medical device. While he was in the hospital, he tried to find applications or software for asthmatics that could help him understand his breathing when an attack occurred and better cope with his situation.
While he did find a few applications, none of them matched his expectations. So, he developed a tool called Wheezy. It collects data and shows information about the user. It has algorithms that can help when an asthma attack occurs. In addition to collecting available data from other sensors such as steps taken, sleep patterns, activity level and other sources that provide pollen count, dust and more—it integrates that data together to offer some insight into what could be causing the user’s attacks.
Wheezy is a hospital-grade spirometer that measures the volume of air inspired and expired by the lungs to determine the health of the lungs.
“The spirometers that are out in the market actually have movable parts, so they do wear and tear over time,” said Stiffler.
Using a proprietary technique with filed patents, the new device makes measurements at several points similar to hospital spirometers.
The company is testing the hardware now and expects to obtain FDA approval in about a year. Prior to the U.S. sales, the company plans on launching in Europe, China and Taiwan by late 2014. Beta test participants are currently being recruited.
Tronics Group
www.tronicsgroup.com
MC10 Inc.
www.mc10inc.com
Zephyr Technology
www.zephyranywhere.com
BAM Labs
www.bamlabs.com
Freescale Technology
www.freescale.com
Medtronic, Inc.
www.professional.medtronicdiabetes.com
Merit Sensor
www.meritsensor.com/
Vicinity Health
www.vicinityhealth.com