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Abstract MXenes have received tremendous attention for flexible electronics owing to their excellent conductivity, water dispersibility, and mechanical flexibility. However, the sediment from the MXene production process is usually discarded as trash, resulting in low utilization. Here, we present a flexible pressure sensor that enables micro‐force sensing and efficient utilization of MXene by confining MXene trash among structured MXene electrodes. Benefiting from the synergistic effect of both the confined micro‐conical structure and easily changeable space of MXene trash, the as‐designed device can detect extremely subtle pressure of 2.9 Pa, deliver a high sensitivity over 4.08 kPa−1, and exhibit a remarkably fast response time (7 ms). These properties make it suitable for monitoring weak force signals from human wrist pulse and even for detecting dynamic responses associated with acoustic waves. This work provides a reference for the versatile and efficient application of MXene in the same device, showing great potential for sustainable production of next‐generation wearable smart electronics.

Piezoelectric wearable electronics, which can sense external pressure, have attracted widespread attention. However, the enhancement of electromechanical coupling performance remains a great challenge. Here, a new solid solution of Ba1−xSrxSn0.09Ti0.91O3 (x = 0.00~0.08) is prepared to explore potential high-performance, lead-free piezoelectric ceramics. The coexistence of the rhombohedral phase, orthorhombic phase and tetragonal phase is determined in a ceramic with x = 0.06, showing enhanced electrical performance with a piezoelectric coefficient of d33~650 pC/N. Furthermore, Ba0.94Sr0.06Sn0.09Ti0.91O3 (BSST) is co-blended with PDMS to prepare flexible piezoelectric nanogenerators (PENGs) and their performance is explored. The effects of inorganic particle concentration and distribution on the piezoelectric output of the composite are systematically analyzed by experimental tests and computational simulations. As a result, the optimal VOC and ISC of the PENG (40 wt%) can reach 3.05 V and 44.5 nA, respectively, at 138.89 kPa, and the optimal sensitivity of the device is up to 21.09 mV/kPa. Due to the flexibility of the device, the prepared PENG can be attached to the surface of human skin as a sensor to monitor vital movements of the neck, fingers, elbows, spine, knees and feet of people, thus warning of dangerous behavior or incorrect posture and providing support for sports rehabilitation.

ZnO is a performance-rich material due to its unique coupling of piezoelectricity and semiconductor properties. However, the intrinsic piezoelectric screening effect of ZnO weakens the electromechanical conversion efficiency and greatly limits its application. To solve this dilemma, it has been recently shown that the piezoelectricity of ZnO can be enhanced by doping to suppress the screening effect, but the exact modulation mechanism remains an open question. Here, we take a new perspective to investigate the piezoelectricity modulation mechanism of Y-doped ZnO at the atomic scale. Both the experimental and simulation results verify the successful suppression of the piezoelectric screening effect. The underlying modulation mechanism of Y-doped ZnO is revealed from the perspective of carrier concentration, work function and bandgap width, respectively. The prepared Y-doped ZnO demonstrates a 97.8%-dropped carrier concentration and a significant improvement (nearly 8.5-fold) in the output performance. This work provides theoretical guidance for the design of ZnO-based piezoelectric devices and is expected to be generalized to other piezoelectric materials, which is of great significance for improving the energy conversion efficiency of piezoelectric devices. [ABSTRACT FROM AUTHOR]