A triple-layer structure flexible sensor based on nano-sintered silver for power electronics with high temperature resistance and high thermal conductivity

With the rapid development of the aerospace, military, electronics, electric power, automotive, and other fields, flexible sensors with high temperature resistance and good thermal conductivity are increasingly in demand. These sensors need to be highly reliable and maintain resistance to heat, humidity, and physical shock so that their terminal units can withstand extreme environments. In this context, conductive adhesives have attracted considerable interest due to their unparalleled potential for the development of high-temperature flexible sensors and power electronics. In this work, a three-layer structure containing silver nanomixes (Ag-NMs), silver microflakes (Ag-MFs), and polyimide (PI) layers was prepared for use in flexible resistive strain sensor by combining the high electrical and thermal conductivity of sintered nano-silver and the flexibility of micron silver using a 3D printing strategy. This resistive strain sensor exhibits low volume resistivity (1.37 × 10−5 Ω·cm), high thermal conductivity (39 W·m−1·K−1), high temperature resistance (capable of stable operation at 250 °C), high sensitivity (ΔR/R0 values of up to 0.43 and 0.45 after bending to 100° at 25 °C and 250 °C, respectively; ΔR/R0 values of up to 0.31 and 0.18 after stretching 2.5% at 25 °C and 250 °C, respectively), and low fatigue after 1000 load-unload cycles. The Ag-NMs/Ag-MFs/PI flexible resistive strain sensor effectively operates at temperatures up to 250 °C for long periods of time, showing great promise for application in harsh environments.