Sweat the details? Nano-bio consortium gets the details from sweat

Boston, MA. The Nano-Bio Manufacturing Consortium (NBMC) October workshop convened Friday October 17 at Northeastern University. Malcolm Thompson of the NBMC welcomed attendees to the workshop by explaining that the consortium formed last year at the behest of the Air Force Research Laboratory (AFRL) to improve human-performance monitoring by measuring factors such as blood pressure, skin temperature, and ECG. In addition, nanotechnology opens the door to measurement of cognition, fatigue, and vigilance. “Cognitive effectiveness is particularly important to the Air Force,” he said, which wants its pilots focused on the mission and wants to be able to measure stress levels.

And in addition to human monitoring, he said, NBMC members are working on projects such as energy-autonomous operation of low-profile munitions systems and the detection of exposure to harmful chemical or biological agents.

Specific projects undertaken by the consortium include a biomarker sensor project, system-packaging project, biometric sensor project, and sweat-management project, with many involving industry and university collaboration, Thompson said. Sweat management was a topic addressed by many presenters at the workshop—sweat provides a means of detecting biomarkers to enable real-time unobtrusive human-performance assessment.

Thompson said that the current state-of-the-art in commercial performance assessment involves monitoring of the biometrics of people with chronic illness remotely or engaging in preventive care. NBMC’s vision is the integration of materials and manufacturing within a common platform to address flexible device applications through the collaboration of universities, the government, and industry.

Rich Chaney of American Semiconductor elaborated on flexibility during his presentation. You can put a flexible strap on a watch, he said, but the watch itself is not really flexible. Wearable technology tethered to a hard box doesn’t lead to customer satisfaction, he said, and people won’t want to wear the product. “We need to cut the cord and get away from those rigid boxes,” he said. “Put everything into the sensor.”

He envisions a stick-on Band-Aid form factor with low profile and low weight. He added that communications would be key to battery life in such a device. You need to build intelligence into the sensor so it can do data and signal processing and report on exceptions—not continually stream data.

Ahmed Busnaina of Northeastern University’s Center for High-rate Nanomanufacturing (CHN) elaborated on points made by Sivasubramanian Somu, research associate professor at Northeastern, during a Thursday afternoon tour of the facility. Busnaina noted that the cost of a printed sensor can be one-tenth or one-hundredth the cost of a silicon sensor. A way to fabricate such sensors is to use CHN’s damascene nanoscale offset printing process, he said, which leverages directed assembly and transfer technologies developed at CHN. The process operates at room temperature, prints down to 20 nm on flexible and hard substances, and scales from microstructures to nanostructures, permitting the directed assembly of nanoparticles.

The process is implemented by the Nanoscale Offset Printing System, or NanoOPS, a prototype of which was demonstrated to 58 companies in September, Busnaina said. (The Boston Globe has more details.) The process could yield carbon nanotube (CNT) and other sensors on silicon or polymer substrates that could detect viruses, bacteria, and antibiotics in drinking water. He cited in particular a nanotube biosensor for metabolic monitoring of sweat—a substance of particular interest to several presenters at the workshop. Unlike blood, sweat can be monitored noninvasively and continuously. “Any biomarker in the blood will exist in sweat,” he said. The sweat sensor could be a very cheap two-terminal device that could be used in hospital labs, by physicians in the hospitals, by consumers, or by athletic departments. But although the sensors could be cheap, the research isn’t—he facetiously though accurately noted that artificial sweat for use in experiments costs $300 per bottle.

Also looking to get details from sweat was Jeffrey Morse of the University of Massachusetts Amherst. In his presentation, he described work with GE Global Research and the University of Cincinnati on low-cost noninvasive wearable sensors for monitoring cognition and stress biomarkers in sweat. The goal, he said, is to monitor as many biomarkers, or biological recognition elements (BRE), as possible. The biomarkers (such as cortisol, dopamine, oxytocin, glucose, lactic acid, and orexin-A) in turn indicate levels of cognition, exercise, and stress.

The researchers are currently limiting themselves to electrical detection (optical sensing would also help, Morse said) and have developed a zinc-oxide FET for orexin-A biomarker detection. The FET offers good specificity and sensitivity, he said.

Challenges involve sensor integration with the sweat patch to enable sweat collection and transport to sensor site. Sensors that could optimize such applications include a multivariable resonance RF sensor developed by GE and an electrochemical impedance spectroscopy (EIS) sensor developed at the University of Cincinnati.

William Adams of the Corey Stringer Institute at the University of Connecticut described the institute’s work in preventing sudden death in sports. The institute is named after a National Football League player who died of heatstroke in 2001. The institute works to track and develop training goals, assess workload, evaluate risk of injury, and create a balance of under vs. over training. The researchers want to monitor factors such as hydration status, heat-accumulation status, heart rate, sweat electrolytes, and environmental conditions including temperature and humidity.

He cited some of the challenges in performance monitoring. A GPS can tell you how far an athlete has run, but it can’t tell you that he stopped at the halfway point and did five pushups. You need extra sensors, such as accelerometers, for that.

Products the institute studies include wearable devices and ingestible temperature monitors. Challenges include integrating data into interpretable results that athletes and coaches can easily understand, he said.

Other workshop presentations covered topics as varied as fabrication of RF antennas, measurement of warfighter trauma, and medical diagnostics. Erik S. Handy of SI2 Technologies Inc. said his company, founded is 2003, conducts R&D for RF applications such as antennas that involve size and cost constraints. The company employs conventional fabrication plus additive manufacturing and printed electronics using direct-write inkjet and micropen dispensing technology.

Examples of products developed include a hybrid wireless system, an ultra-lightweight conformal antenna array, and a mortar diagnostic fuze. The company’s roadmap includes transistors that double as biosensors. The company is also studying blast dosimeters involving helmet-mounted sensors that measure how much trauma a warfighter has suffered. The technique would allow non-experts to record their own EEGs. Apart from military applications, he envisions a $30 portable brain recorder that would find use in sports and education as well as defense.

And William Peter of MIT described the Institute for Soldier Nanotechnologies (ISN), which performs basic research and supports the transitioning of its technology to the Army and industry partners to meet defense and commercial dual-use needs. The “S” in ISN is for soldier, he said, but the technology can apply to sailors, marines, and civilians. ISN, he said, involves symbiotic partnering of the complementary assets of the university, Army, and industry. ISN has a dedicated facility on the MIT campus, and industry partners include XTALIC, FLIR, Raytheon, TSI, JEOL, the Center for Integration of Medicine and Innovative Technology (CIMIT), and Lockheed Martin.

Projects involve photonic crystal nanostructures, optoelectronic fiber devices, and novel nanoparticles. Nanocrystal dye constructs that respond to pH, O2, and glucose, for instance, can serve as environmental reporters for medical diagnostics. Other medical applications involve fiber devices and smart fabrics that enable full body sensing. And OmniGuide Inc., he said, employs a hollow-core fiber for use in laryngology, gynecology, neurosurgery, and otology. The fiber, he said, can snake inside the human body to enable minimally invasive laser surgery. Next-generation drug and vaccine delivery systems will be nanoparticle-based systems that offer unprecedented delivery efficiency and efficacy, he added. 

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