Harvesting electrical energy from different forms of water by using the hydrovoltaic effect is a promising approach to green energy acquisition. However, at present, different devices are required to obtain electrical energy from different water forms, and the output performance of the devices is not high, which greatly reduces the convenience and effectiveness of harvesting electrical energy from different water forms. Here, a carbon nanofiber electrode with a hierarchical porous structure capable of promoting water molecule adsorption, rapid penetration, and diffusion is reported. Besides, the electrode acts as a nanofluidic diode with anodic aluminum oxide in which the built‐in electric field drives selective separation and directional transport of ions and efficient ion/electron current conversion at the electrodes. Unlike typical hygroelectric devices, the device can work with moisture (93% relative humidity, 25 °C, open‐circuit voltage (VOC) ≈ 1.1 V, short‐circuit current density (JSC) ≈ 27 µA cm−2), water droplets (2 µL, VOC ≈ 1.03 V, JSC ≈ 640 µA cm−2), and bulk water (VOC ≈ 1.15 V, JSC ≈ 256 µA cm−2). It provides an efficient way to generate electricity in multiform water environment, greatly broadening the working scene and improving the adaptability of the device in complex weather environments.

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Flexible sensors with the ability to precisely detect the full range of tiny strain (less than 0.1%), small strain (within 1%), and large strain (≈50%) are in significant demand to satisfy the requirements for electronic skin applications. More importantly, the sensor performance is required to be accurate and reliable when operating in some unconstrained environments, such as excessive extension, high bending, torsion, and scratching impact. However, it remains challenging to meet all these requirements simultaneously in a single strain sensor. Herein, an ultrathin composite film composed of reduced oxide (rGO) and carbon tube (CNT) is prepared, and then transferred onto a modified elastomer polydimethylsiloxane surface that forms strong hydrogen bond interaction with the film. The as‐fabricated sensor achieves wide range and high sensitivity (gauge factor (GF) ≈ 105, 160, and 310 in the strain regions of 0–25%, 25–40%, and 40–50%, respectively). More importantly, the proposed strain sensor performs mechanical robustness, low hysteresis, scratch resistance due to the effective improvement of interfacial slipping and delamination. The sensor can be used to monitor human physiological information, including pulse waveforms in a variety of wrist postures and acoustic vibration signal (≈7 kHz).