Boosted mechanosensitivity of stretchable conductive composite strain sensors based on kirigami cut design

Abstract

Despite the recent advances in conductive elastomer composites (CECs) for wearable strain sensing, CEC-based resistive sensors usually suffer from limited mechanosensitivity, particularly at low strains. Here, we present a facile and universal way of boosting the strain sensitivity of resistive CEC sensors based on kirigami-cut designs. The strain-dependent reversible opening of kirigami cuts in the CEC sensory layer enables the device to exhibit high sensitivity over a wide strain range by allowing its resistance to increase rapidly at low strains and remain elevated at high strains. Various designs of kirigami-cut sensors are easily and reproducibly prepared via a programmable direct cut-patterning process. The fabricated sensors exhibit high maximum gauge factors of ∼63.1 to ∼5013.1 according to the kirigami design in low strain region (usually <7%) and operate stably with up to ∼82.8 times larger resistance change than the pristine device at 80% strain. The sensor response is also highly stable and reversible, even when the device is subjected to repeated stretching (1000 cycles at 80%). Based on the boosted sensitivity coupled with mechanical stretchability, the kirigami-cut sensors are successfully used to sensitively monitor a wide range of human activities in real time, highlighting their practicality in diverse wearable sensor system applications.