Ion-Selective Mobility Differential Amplifier: Enhancing Pressure-Induced Voltage Response in Hydrogels

Piezoionics is an emerging mechanical-electrical energy conversion paradigm that enables self-powered sensing systems for next-generation intelligent wearable electronics. However, there are currently no rational design approaches to enhance the stimulus response of piezoionic devices. Here, we present a strategy using crown ether as ion-selective mobility differential amplifiers for enhancing the pressure-induced voltage response in ionic polyvinyl alcohol (PVA) hydrogels. The crown ether grafted PVA (PVA-CE) hydrogel prototype achieves a 30-fold amplified piezoionic coefficient of 1490 nV Pa^-1 within 0-1 kPa, compared to 49 nV Pa^-1 of the unmodified PVA. The PVA-CE exhibits an ultra-low pressure detection limit of 0.2 Pa with a fast response time of 18.1 ms. Leveraging these properties, we further demonstrate arrayed pressure sensing with a PVA-CE piezoionic skin, analogous to the human somatosensory network. These capabilities hold great promises for emerging healthcare applications such as synthetic biology, soft robotics, and beyond.