Ultrahigh Sensitivity Flexible Pressure Sensors Based on 3D‐Printed Hollow Microstructures for Electronic Skins

Abstract Here, ultrahigh sensitivity flexible pressure sensors comprised of 3D‐printing flexible hollow microstructure substrates, gold film spray‐coated on the substrates, and Ag interdigital electrodes are reported. The finite element analysis (FEA) shows that the hollow microcylinder structure has better compression performance compared to solid microcylinder structure. Diverse solid and hollow microstructures, such as microcylinder, microsawtooth, and microrectangle structures are built to investigate the performance difference. The sensitivity of the sensor with hollow microcylinder structure is nearly 100% higher than that of the solid microcylinder structure sensor. By comparing the sensors with different spray‐coating time of Au nanoparticles, the influence of electrode microcrack on sensitivity is revealed. The flexible hollow microcylinder structure sensor with electrode microcrack effect shows ultrahigh sensitivity of 419.622 kPa −1 in the ultralow pressure range (< 100 Pa), rapid response time (30.76 ms), and recovery time (15.17 ms). To show the great performance of the sensor, it is used to detect human physiological signals such as cheek bulging, throat swallowing, and artery pulse. To realize the spatial sensing resolution, a 3 × 4 pressure sensor array is fabricated. The applications of the sensor may pave the way in human physiological signals monitoring and electronic skins in the future.