The flexible piezoresistive sensor has attracted more and more attention in health monitoring as a man−machine interface due to its simple structure and convenient signal reading. Herein, a highly sensitive flexible piezoresistive sensor with a 3D conductive sensing unit is presented. The 3D conductive sensing unit consists of a 3D network thermoplastic elastomer (TPE) substrate fabricated by fused deposition molding (FDM) 3D printing and carbon nanotubes (CNTs) conductive layer embedded into the surface of the TPE substrate. The finite element analysis (FEA) shows that the 3D network structure has excellent mechanical properties, which is basically consistent with the experimental results. Experimentally, based on the novel 3D conductive network, the flexible piezoresistive sensor exhibits superior comprehensive properties in the compressed or stretched state. The sensitivity of the sensor is as high as 136.8 kPa −1 at an applied pressure <200 Pa while compressing, and its gauge factor (GF) can reach 6.85 while stretching. Meanwhile, the sensor shows excellent stability and durability performance because CNTs embedded into the surface of the TPE substrate have little effect on the flexibility of the elastomeric composite of the sensor. Finally, the piezoresistive sensor is used for detecting subtle muscular movements (facial expressing and throat swallowing) and body movement like arm bending. These results indicate that the novel 3D conductive structure provides an alternative way to improve the performance of piezoresistive sensors and extend their potential applications in health monitoring.

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.

The flexible piezoresistive sensors have great potentials in wearable electronics. Sensitivity and stability are the key parameters for the piezoresistive sensors. However, the 3D flexible piezoresistive sensors are difficult to meet high sensitivity and good stability simultaneously. Herein, combining 3D printing with a carbon nanotubes (CNTs) surface‐filled (SF) structure that CNTs are filled in the surface of styrene–ethylene–butylene–styrene (SEBS) substrate, a highly sensitive, stable, and flexible piezoresistive sensor is developed. Experimental results show that the CNTs SF sensor not only has high sensitivity similar to the CNTs surface‐coated sensor, but also has good stability similar to the CNTs integral‐filled sensor. Due to the 3D network structure and SF CNTs conductive layer, the sensor shows high stretchability of 20.9 times, good sensitivity of 161.53 kPa−1 at an applied pressure <250 Pa under compressed status, high gauge factor of 7.24 under stretched status, excellent stability (>2000 cycles), the short mechanical response time (149 ms) and recovery time (75 ms). Meantime, the sensor shows an obvious response to temperature. Furthermore, the sensor is used to detect tiny and big human activities such as speaking, throat swallowing, and breathing, exhibiting its great potential for application in wearable electronics.

Nanosecond laser shock annealing is used to induce ultrafast organic salt diffusion into the PbI2 layer to modulate the crystalline structure, residual tensile strain, and electron transport kinetics of perovskite films.