An international collaboration led by Pennsylvania State University has produced a self-powered stand-alone sensor system that can monitor gas molecules in the environment or in human breath at a fraction of the cost. The system combines nanogenerators and micro-supercapacitors to collect and story the energy generated by human movement.
The researchers published last week in Nano Letters an approach that costs just a few dollars in materials and uses widely available equipment. This development is the culmination of many years of work led by lead author Huanyu “Larry” Cheng, James L. Henderson Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State University.
“This really combines previous work that has continued to develop wearable gas sensors,” Cheng said. “Most sensor R&D is focused on manufacturing device materials, where we used one material to manufacture multiple components on a single platform that work together as a standalone system.”
Cheng and his team have previously developed sensors that detect nitrogen dioxide in exhaled air, which can indicate various lung diseases, and other gases that can indicate poor environmental air quality. bottom. They also invented MXenes, or laser-induced graphene foam materials containing two-dimensional transition metals that are less reactive than other metals. New materials and new manufacturing methods enable stretchy sensors that can bend with human movements. Researchers have also applied this approach to fabricate stretchable micro-supercapacitors that can store energy generated by human movement.
In this paper, the group combined these efforts. They first applied the laser to a previously developed 3D porous graphene foam on a flexible substrate. The researchers then sprayed his MXenes onto the graphene foam and used another laser to bond the foam and his MXenes into the nanocomposite material. We then transferred the nanocomposite material to a pre-tensioned elastomer and slowly released it. This sustained release crumples the nanocomposites and can form different patterns for sensors, nanogenerators and micro-supercapacitors.
“Using this laser is like toasting bread. It makes the surface of the bread more stable,” Cheng said, adding that the laser uses carbon dioxide to alter the surface of the material. I explained. “The end result is a more stable and porous product than it started with. This material makes the sensor more sensitive and makes other components more conductive.”
Cheng says the lasers used are available at most processing plants.
“These materials are cheap and the more expensive tools are widely available. There are hundreds of these lasers at Penn State alone.” can be scaled up for clinical use.”
According to Cheng, the same nanocomposite materials that make up each device make the system’s components work seamlessly together. The 3D nanocomposite foam is pre-strained to create a ‘crumpled’ effect, so each component can be stretched and bent and even adhered to human skin or clothing without loss of sensitivity.
“The improved electrical conductivity, mechanical robustness, and specific surface area of crumpled porous graphene/MXene with simple fabrication offer opportunities for applications in standalone stretchable device platforms,” said Zhang. says.
To demonstrate a proof of concept, researchers wore gas sensors under their noses and wrists, nanogenerators in their shoes, and an array of micro-supercapacitors in their shirts. The person exercised vigorously with nanogenerators collecting the energy generated by the movement of his legs. That energy was stored by a micro-supercapacitor, and he used this power to collect data from the gas sensor and send it to his Bluetooth receiver where scientists could analyze the data. Sensors continuously monitored both the exhaled air and the nitrogen dioxide environment.
“The readings were consistent with readings from commercial sensors,” Cheng said. He also notes that the system showed stable rates over 50 days in laboratory tests, demonstrating the long-term stability of the system in real-world applications. “The design strategy and demonstration of this study paves the way for the design, manufacture, and application of next-generation biointegrated electronics for healthy aging and precision medicine.”
Original: Standalone sensor systems use human movement to monitor health and the environment
Than: Pennsylvania State University
