A dual-trigger mode ionic hydrogel sensor for contact or contactless motions recognition

The intelligent flexible sensors with high responsivity and detectivity are highly desirable for wearable devices and human–machine interfaces (HMI). However, the exiting sensors are usually limited to the onefold detection performance for either contact or noncontact mode. Here, a sandwiched hydrogels capacitive system is designed to fabricate a multi-operational modes ionic sensor (MOMS) for recognizing mechanical stimuli and remote gestures simultaneously. The novel MOMS performs satisfying sensitivity (1.7 gauge factor and 3.3 Pa-1 pressure sensitivity), rapid response for contactless gestures recognition, a quite wide working range (up to 100 kPa and 300% elongation) and high touch-free operating distance (40 mm). Moreover, the spatial resolution of the structured sensor array could meet the accurate positioning requirements under both contact and touch-free conditions. It is the first time that a capacitive hydrogel system processes outstanding performances for detecting the contact stimuli and noncontact hands motions at the same time. Hence, the MOMS will make significant advances in intelligent detection techniques and could provide an innovation thinking for the application of synchronous monitoring devices.