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Wearable flexible piezo-resistive pressure sensors hold a wide-ranging potential in human health monitoring, electronic skin, robotic limbs, and other human–machine interfaces. Out of the most successful recent efforts for arterial pulse monitoring are sensors with micro-patterned conductive elastomers. However, a low-current output signal (typically in the range of nano-amperes) and bulky and expensive measurement equipment for useful signal acquisition inhibits their wearability. Herein, through a finite element analysis we establish the design rules for a highly sensitive piezo-resistive pressure sensor with an output that is high enough to be detectable by simple and inexpensive circuits and therefore ensure wearability. We also show that, out of four frequently reported micro-feature shapes in micro-patterned piezo-resistive sensors, the micro-dome and micro-pyramid yield the highest sensitivity. Furthermore, investigations of different conductivity values of micro-patterned elastomers found that coating the elastomer with a conductive material (usually metallic) leads to higher current response when compared to composited conductive elastomers. Finally, the geometric parameters and spatial configurations of micro-pyramid design of piezo-resistive sensors were optimized. The results show that an enhanced sensitivity and higher current output is achieved by the lower spatial density configuration of three micro-features per millimeter length, a smaller feature size of around 100 μm, and a 60–50 degrees pyramid angle. 

Black phosphorus (BP) as a rising star among 2D materials has attracted attention for a wide range of applications due to its fascinating properties. The key point for the real application of phosphorene depends on its exfoliation technique to produce high‐quality nanosheets. In recent years, tremendous efforts have been made in the preparation and energy storage application of phosphorene and phosphorene‐based hybrid electrodes. Herein, the state‐of‐the‐art liquid‐based exfoliation and characterization of phosphorene fabricated by sonication, anodic and cathodic electrochemical exfoliation, and bipolar electrochemical exfoliation in diverse solutions and conditions are discussed. In addition, the electrochemical properties and storage mechanism of phosphorene‐based electrodes for rechargeable batteries and supercapacitors are discussed. Finally, the challenges and opportunities of phosphorene nanosheets in terms of exfoliation and energy storage applications are addressed.