A smart face mask that can conveniently monitor breath information is beneficial for maintaining personal health and preventing the spread of diseases. However, some challenges still need to be addressed before such devices can be of practical use. One key challenge is to develop a pressure sensor that is easily triggered by low pressure and has excellent stability as well as electrical and mechanical properties. In this study, a wireless smart face mask is designed by integrating an ultrathin self‐powered pressure sensor and a compact readout circuit with a normal face mask. The pressure sensor is the thinnest (totally compressed thickness of ≈5.5 µm) and lightest (total weight of ≈4.5 mg) electrostatic pressure sensor capable of achieving a peak open‐circuit voltage of up to ≈10 V when stimulated by airflow, which endows the sensor with the advantage of readout circuit miniaturization and makes the breath‐monitoring system portable and wearable. To demonstrate the capabilities of the smart face mask, it is used to wirelessly measure and analyze the various breath conditions of multiple testers.

Flexible and biocompatible integrated photo‐charging devices consisting of photovoltaic cells and energy storage units can provide an independent power supply for next‐generation wearable electronics or biomedical devices. However, current flexible integrated devices exhibit low total energy conversion and storage efficiency and large device thickness, hindering their applicability towards efficient and stable self‐powered systems. Here, a highly efficient and ultra‐thin photo‐charging device with a total efficiency approaching 6% and a thickness below 50 µm is reported, prepared by integrating 3‐µm‐thick organic photovoltaics on 40 µm‐thick carbon nanotube/polymer‐based supercapacitors. This flexible photo‐charging capacitor delivers much higher performance compared with previous reports by tuning the electrochemical properties of the composite electrodes, which reduce the device thickness to 1/8 while improving the total efficiency by 15%. The devices also exhibit a superior operational stability (over 96% efficiency retention after 100 charge/discharge cycles for one week) and mechanical robustness (94.66% efficiency retention after 5000 times bending at a radius of around 2 mm), providing a high‐power and long‐term operational energy source for flexible and wearable electronics.

Wearable Healthcare Devices Convenient breath monitoring via wearable devices is helpful for personal healthcare, especially during the COVID‐19 pandemic. In article number 2107758, Kenjiro Fukuda, Takao Someya, and co‐workers develop a wearable smart face mask based on an ultrathin self‐powered pressure sensor with high output ability, and various breath conditions from multiple testers are wirelessly detected and analyzed.

The nanopatterning of the surfaces of polymer substrates enhances the performances of photovoltaics. Ultraflexible organic photovoltaics (OPVs) are one of the promising energy harvesters for wearable electronics. A reduction in incident light angle dependence while maintaining the power conversion efficiency (PCE) is desirable for wearable electronics devices in which the angle of incident light continuously changes due to the deformation of the device. However, the nanopatterning of the ultrathin polymer substrates of ultraflexible OPVs using the reported methods is challenging because they fatally damage the substrates. Here, the fabrication of ultraflexible OPVs having a low incident light angle dependence while maintaining a PCE of 10.5% by developing ultrathin nanograting polymer substrates is reported. The nanograting‐patterned fluorinated polymer enables the formation of periodic nanograting structures onto the back surface of a 1 µm thick polymer substrate having a pitch of 760 nm and a height of 100 nm, while the opposite surface remains flat after the formation of the planarization layer. Furthermore, with the nanopatterning of the ultrathin substrate, electron‐transporting layer, and active layer, the ultraflexible OPVs exhibit a PCE of 10.8%. The combination of new materials with the developed patterning method is expected to afford even greater performances.

In article number 2000523, Kenjiro Fukuda, Takao Someya and co‐workers integrate flexible organic photovoltaics with a carbon nanotube/polymer‐based supercapacitor on a 1‐µm‐thick ultrathin substrate, enabling an efficient and ultra‐flexible design. It exhibits a total system efficiency approaching 6% and a thickness below 50 µm, and a superior 94.66% efficiency retention after 5000 bending cycles at a radius of around 2 mm.

Water vapor plasma treatment enables direct gold bonding on flexible polymer films in air at ambient temperatures.

Cyborg insects have been proposed for applications such as urban search and rescue. Body-mounted energy-harvesting devices are critical for expanding the range of activity and functionality of cyborg insects. However, their power outputs are limited to less than 1 mW, which is considerably lower than those required for wireless locomotion control. The area and load of the energy harvesting device considerably impair the mobility of tiny robots. Here, we describe the integration of an ultrasoft organic solar cell module on cyborg insects that preserves their motion abilities. Our quantified system design strategy, developed using a combination of ultrathin film electronics and an adhesive–nonadhesive interleaving structure to perform basic insect motion, successfully achieved the fundamental locomotion of traversing and self-righting. The body-mounted ultrathin organic solar cell module achieves a power output of 17.2 mW. We demonstrate its feasibility by displaying the recharging wireless locomotion control of cyborg insects.

Recent progress in organic photovoltaics (OPVs) has led to an increased importance of laboratory-scale fabrication in ambient air using solution processes. However, the effect of the existence of both ambient air and light during the formation of a photoactive layer on the performance of fabricated devices has not been elucidated thus far in detail. Here, we show that photoactive layer formation in completely dark conditions enables air-processable OPVs with a high power conversion efficiency. The degradation in OPV performance caused by the coexistence of air and room light was confirmed by systematically examining atmospheric and room-light irradiation conditions during the formation and drying of the photoactive layer. Moreover, the degradation rate was much faster than that in the case of dried solid photoactive layers exposed to room light in ambient air. The photoactive layer with non-fullerene acceptors showed a much slower degradation rate, owing to room light, than that with fullerene acceptors. Based on these findings, we demonstrate that by eliminating light during formation, slot-die-coated OPVs in ambient air show comparable performance to that of spin-coated OPVs in an inert glovebox.