Broadband Iontronic Pressure Sensor Inspired by Nociceptor for Pain Recognition

Human pain perception is a representative sensory function that activates self-protection mechanisms. The inability to detect pain can lead to serious injury and permanent damage. To emulate pain sensation, the sensor should be capable of detecting a broad range of pressures, while efficiently filtering out minor or harmless tactile inputs. To address this critical need, we developed a broadband pressure sensor that mimics human nociceptors and can detect both tactile and pain stimuli. This sensor comprises an air gap and ion gel composite for varying the capacitance according to the applied pressure. This can distinguish the small, moderate, and painful touches using hardware-based (air gap) and software-based thresholding. The sensor can set the hardware threshold (0.1 mm gap) as 200 kPa and achieve a wide sensing range up to 3.6 MPa with high sensitivity (11.2 kPa^-1) and excellent linearity within the range ∼900 kPa. The sensor integrated into a prosthetic hand exhibited an avoidance feedback response under stimuli exceeding the pain threshold. This iontronic sensor has potential applications in wearable monitoring, prosthetic tactile feedback, and protective systems for collaborative robots, providing a technological basis for safer interaction in individual with pain insensitivity.