Sensitive humidity sensor based on moisture-driven energy generation

The emergence of novel self-powered humidity sensors has attracted considerable attention in the fields of smart electronic devices and personal healthcare. Herein, self-powered humidity sensors have been fabricated using a moisture-driven energy generation (MEG) device based on asymmetric tubular graphitic carbon nitride (g-CN) films prepared on anodized aluminum (AAO) template. At a relative humidity (RH) of 96%, the MEG device can provide an open-circuit voltage of 0.47 V and a short-circuit current of 3.51 µA, with a maximum output power of 0.08 µW. With inherent self-powered ability and humidity response via current variation, an extraordinary response of 1.78 × 106% (41%–96% RH) can be gained from the MEG device. The possible power generation mechanism is that g-CN/AAO heterostructure can form ion gradient and diffusion under the action of moisture to convert chemical potential into electrical potential, evoking a connaturally sensitive response to humidity. Self-powered respiration monitoring device based on the sensor is designed to monitor human movement (sitting, warming up, and running) and sleep status (normal, snoring, and apnea), maintaining excellent stability during cumulative 12-h respiration monitoring. This self-powered humidity sensing technology has promising potential for extensive integration into smart electronic and round-the-clock health monitoring devices.