Additively Manufactured Flexible Electronics Filled with Ionic Liquid for Cryogenic Pressure Sensing

Abstract

Flexible electronics have attracted increasing attention and are extensively used in medical care and health monitoring applications. However, research on their applications in low-temperature environments is limited, mainly owing to material intrinsic limitation. In this work, a cryogenic pressure sensor using low-melting (−71 °C) ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) is fabricated via the template removal method. The sensor unit can function at temperatures ranging from −50 to 30 °C, with improved sensing performance at lower temperatures. At −50 °C, it demonstrates an ultralow detection limit of 0.5 Pa and a high sensitivity of 2.0 × 105 Ω/kPa, thereby enabling the detection of dynamic pressure loads with different frequencies (0.2 to 2 Hz) and waveforms (sine and triangle). Subsequently, these units are integrated into a 3 × 3 array and embedded into a bionic thumb. The sensor can accurately identify up to 9 independent touch points and recognize dynamic sliding with velocities in the range of 0.31 to 4.42 cm/s at an extremely low temperature (−50 °C), thus demonstrating remarkable multitouch and sliding trajectory recognition capabilities. Furthermore, the proposed sensor unit is expected to contribute to the research on the human–machine interface of space suits.