Highly sensitive and Durable crack structures on Flexible, Friction-Resistant substrates

Abstract

Flexible sensors using crack-sensitive structures have garnered significant interest due to their exceptional sensitivity stemming from crack disconnection and reconnection mechanisms. However, studies on the sensor’s crack size is imperative, as cracks are typically regarded as defective or harmful in real-life applications. In this study, a new multi-layer configuration (PDMS/Ecoflex)/CNT/PET/(PDMS/Ecoflex) is employed to create piezoresistive pressure sensors with reduced crack size labelled crack free, demonstrating extensive linearity and exceptional sensor responsiveness. The crack size on the conductive layer was significantly reduced using Cetyl Trimethyl Ammonium Bromide cationic surfactant. PDMS/Ecoflex (PE) blend matrix was shown to have an outstanding mechanical and tribological properties compared to PDMS and Ecoflex alone achieving flexibility of up to 500 %, decreasing friction by 56 %, and enhancing wear resistance. The crack-free sensors exhibited a linearity of 0.99, high sensitivity (GF = 132), and low response time (19 ms). Furthermore, crack-free pressure sensors exhibit distinct characteristics such as low detection limits, rapid response/recovery, negligible hysteresis, excellent dynamic response (over 1000 cycles), and exceptional long-term durability. the cracked-free sensor was compared to a standard crack-based sensor to analyze the crack appearance and mechanism on the overall performance and application including health monitoring and various body movement detection.