Full-Self-Powered Humidity Sensor Based on Electrochemical Aluminum–Water Reaction

Abstract

A detailed examination of the principle of operation behind the functioning of the full-self-powered humidity sensor is presented. The sensor has been realized as a structure consisting of an interdigitated capacitor with aluminum thin-film digits. In this work, the details of its fabrication and activation are described in detail. The performed XRD, FTIR, SEM, AFM, and EIS analyses, as well as noise measurements, revealed that the dominant process of electricity generation is the electrochemical reaction between the sensor’s aluminum electrodes and the water from humid air in the presence of oxygen, which was the main goal of this work. The response of the sensor to human breath is also presented as a demonstration of its possible practical application.

Recent Development of Moisture‐Enabled‐Electric Nanogenerators

“…Several major industries such as the chemical, pharmaceutical, and electronics industries have compulsory requirements to install humidity sensors to ensure product quality. [93] Most of the previous reported MEENGs' output performances have indicated a quasi-linear dependence on RH, so introducing higher RH is one of the generic strategies to enhance electricity generation. [48] However, many of these devices have a relatively high humidity threshold, which means that several types of MEENGs would not work under low RH.…”

“…Several major industries such as the chemical, pharmaceutical, and electronics industries have compulsory requirements to install humidity sensors to ensure product quality. [ 93 ]…”

Self-Powered Wearable Breath-Monitoring Sensor Enabled by Electromagnetic Harvesting Based on Nano-Structured Electrochemically Active Aluminum

“…It was shown that this structure reacted in the presence of high humidity levels, close to 100% RH [31]. It was also proven [32] that the signal from this kind of structure was a consequence of the electrochemical reaction between aluminum and water on the surface of the sensor. In this work, the concept of a sensor based on activated aluminum is extended by adding electromagnetic (EM) harvesting and an electronic rectifier in order to modulate the output from the EM antenna.…”

“…The method of aluminum activation described here is a novel method, discovered and used for the first time for aluminum-battery-based sensor activation [31,32]. Other methods have been used for aluminum activation [42,43].…”

“…In the field of self-powered humidity sensors, one approach is to generate electricity directly from moisture and use it as a humidity detector [21][22][23][24][25][26][27][28][29], even though this approach can only provide the ability to detect the difference between very high and very low humidity levels. Other examples are based on TiO 2 nanowire networks [15,30] and the aluminum-air battery principle [31,32]. Aluminum-air batteries represent a specific example of the much wider class of the so-called "metal-gas" batteries [33].…”