MXene Nanosheet-Enhanced Ionotronic Hydrogels for Wireless Powering and Noncontact Sensing

Abstract

Smart actuators and wearable and implantable devices have attracted much attention in healthcare and environmental sensing. Flexible electronic and ionic materials are the two main approaches used to construct these devices. Among them, hydrogel-based ionic materials offer unique advantages, such as biocompatibility and adaptable mechanical properties. However, ionic hydrogels encounter challenges in achieving wirelessly powered and noncontact sensing. To address this, we introduce MXene nanosheets to construct ionotronic hydrogels. Leveraging the rich surface charges and electronic conductivity of MXene nanosheets, ionotronic hydrogels can harvest vibrational and electromagnetic waves as electrical energy and enable noncontact sensing. Under ultrasound, it can continuously generate voltages up to 85 V and light up light-emitting diodes, promising wireless charging of implanted devices. In addition, it achieves an absorption coefficient of 0.2 for 915 MHz electromagnetic waves, enabling noncontact sensing through radio frequency identification. Notably, the physically crosslinked network of the MXene-based hydrogels maintained structural and performance stability under ultrasonic stimulation and exhibited self-healing properties. Even when cut into two halves, the self-healing hydrogel fully regenerates its original performance. This study provides insight into the development of ionotronic hydrogels for wirelessly powered and noncontact sensing in smart actuators and wearable and implantable applications.