Highly Sensitive, Ultrawide Range, and Multimodal Flexible Pressure Sensor with Hierarchical Microstructure Prepared By a One-Step Laser Printing Process

The hierarchical microstructures composed of surface microstructures and porous structures on soft materials have attracted more and more attention because of their effectiveness in improving flexible sensor performance. However, the preparation methods of the hierarchical microstructures are faced with the problems induced by complex process, high cost, and low efficiency. Up to now, there is no one-step method that can directly realize the hierarchical microstructure on soft materials, even polydimethylsiloxane (PDMS) as the most common soft material. Herein, using glucose additive as porogen and endothermic agent, a simple, low-cost, and fast laser thermal printing one-step process is developed for the preparation of porous PDMS film with surface microstructure. Based on the hierarchical structural PDMS film, a multimodal flexible pressure sensor that can sense tension, compression, and torsion is realized. Due to the hierarchical microstructure composed of surface microstructure and porous structure, the sensor exhibits a high sensitivity of 36.66 kPa(-1) in 0-0.6 kPa, a ultrawide sensing range of 3000 kPa, a 100% elongation, and a high gauge factor of 315.13. The application of the sensor in the monitoring of physiological signals, dynamic loads, and robotic flexible gripper demonstrates the potential of the laser thermal printing process in porous PDMS-based sensors.