Rapid Template-Transferred Printing of Gelatin-Based Ionogels with Bioinspired Hierarchical Microstructures for Flexible Tactile Sensors

Abstract

Flexible pressure sensors are pivotal for e-skin, artificial intelligence interactions, and personalized medicine. Nevertheless, integrating high sensitivity, a broad detection range, and biodegradability remains difficult. Herein, we developed a flexible piezoresistive tactile sensor comprising a gelatin/deep eutectic solvent/sodium citrate (GDS) ionogel substrate, a carbon nanotube (CNT)/gelatin sprayed hierarchical microstructure sensing layer, and a gelatin gel-based interdigitated electrode. The hierarchical microstructures and interdigital microgrooves, fabricated via template transfer printing, mimic the interlocking spinous structures of human skin, enhancing stress distribution and sensitivity. Due to the superior mechanical properties of the GDS ionogel matrix and the "interlocking effect" between the microstructures and interdigital electrode, the sensor achieves high sensitivity (6.16 kPa^-1), broad range (up to 173 kPa), fast response (<10 ms), low detection limit (10 Pa), and excellent cycling stability over 8000 cycles. Applications in human activity monitoring and human-computer interaction highlight its potential for ultraprecise sensing.