Microstructures can effectively improve the sensing performance of flexible piezocapacitive sensors. Simple, low-cost fabrication methods for microstructures are key to facilitating the practical application of piezocapacitive sensors. Herein, based on the laser thermal effect and the thermal decomposition of glucose, a rapid, simple, and low-cost laser direct-printing process is proposed for the preparation of a polydimethylsiloxane (PDMS)-based electrode with a hybrid microstructure. Combining the PDMS-based electrode with an ionic gel film, highly sensitive piezocapacitive sensors with different hybrid microstructures are realized. Due to the good mechanical properties brought about by the hybrid microstructure and the double electric layer induced by the ionic gel film, the sensor with a porous X-type microstructure exhibits an ultrahigh sensitivity of 92.87 kPa–1 in the pressure range of 0–1000 Pa, a wide measurement range of 100 kPa, excellent stability (>3000 cycles), fast response time (100 ms) and recovery time (101 ms), and good reversibility. Furthermore, the sensor is used to monitor human physiological signals such as throat vibration, pulse, and facial muscle movement, demonstrating the application potential of the sensor in human health monitoring. Most importantly, the laser direct-printing process provides a new strategy for the one-step preparation of hybrid microstructures on thermal curing polymers.

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.

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