Flexible and Stretchable Wearable Sensors for Human Motion and Physiological Monitoring
With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. However, currently available devices have limits on stretchability, flexibility, portability and high cost because of their functional materials. Therefore, there is a critical need to develop conductive materials that can withstand repeated large strain, pressure and can be manufactured into discreet, low cost, and dense arrays with high stretchability, flexibility, and sensitivity.
This research presents a shape memory polymer embedded highly flexible and stretchable wrinkled carbon nanotube thin film wire. We preassemble CNTs on a shape memory polymer substrate with wrinkles, to demonstrate significant densification, improvement of stretchability and high electrical performance followed by the shrinking of the substrate. And we transferred to Ecoflex or PDMS thin films which utilized as wearable and skin-mountable strain sensor and pressure sensor for human motion and physiological signals detection. Unlike pre-existing sensors, these wrinkled CNT strain and pressure sensors can be worn conformal to human skin and are capable to endure higher strains and pressure. The piezoresistive response of shrink induced wrinkled CNT thin films demonstrated conductive performance in excess of high strain and pressure. Also the wrinkled CNT wires exhibited consistent performance after repetitive stimulus. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible to conventional manufacturing processes. In this proposal, we focus on this wrinkled CNT concept toward practical applications in flexible and highly sensitive sensor for monitoring human physiological signals as wearable sensors which relates to the health of individuals.