A Self‐Powered Gas Sensor Based on Coupling Triboelectric Screening and Impedance Matching Effects

Abstract

triboelectrification and electrostatic induction, it enables to convert the mechanical energy into electrical signal. [4] When triggering in a gaseous ambient, a dipole layer is formed after contact-electrification between two triboelectric materials. [5] The surface triboelectric charge density is greatly influenced by the surface alteration of certain chemisorption of the molecular oxygen species. During the chemisorption process of some gas molecules, the additional free electrons acquired by triboelectric material would screen the triboelectric charge generated on the surface of the triboelectric layer, thus resulting in the variation of electrical output signal. [6] In this case, TENG can be treated as a self-powered gas sensor simply without any external power source. [7] However, the ambient environment, including temperature, humidity, motion frequency, and amplitude all affect the output electric signals and disrupt the sensing signals, resulting in a poor selectivity, stability, and reliability.To improve the performance of TENGbased gas sensors, the concept of impedance matching effect induced triboelectric gas sensing systems have been proposed. [8] As well known, the sensing mechanism of semiconductor gas sensor is based on varied resistance of the sensing materials in response to the gas concentration. When connecting a TENG with a traditional semiconductor gas sensor, the output of TENG would vary with the working status of the load sensor due to the impedance matching effect. [9] Every part in such a system works independently and does not interfere with each other, providing a strong theoretical basis and technical support for self-powered triboelectric gas sensors (SPTGS). However, due to the large internal impedance of TENG (≈GΩ level), the fluctuation of electrode resistance induced slight change on electrical signal usually was negligible. [10] Therefore, the previous works generally employed metal as electrode and did not take into account the impedance matching effect in the construction of triboelectric sensors. [11] In actual fact, when triboelectric gas sensors utilize sensitive materials as triboelectric layer and electrode, the oxygen species absorbed on both triboelectric layer and electrode would react with the target gas molecule, leading to a change of surface state, electrical properties, or work function. [12] Thus, the variation in impedance

Gas-Responsive and Self-Powered Visual Composite Langmuir–Blodgett Films for Ultrathin Gas Sensors

“…As a result, the resistance of the film increases, thus increasing the Voc of the device. 31 Subsequently, when the LB film was exposed to NH 3 , the reason for the decrease in Voc may be the occurrence of deprotonation leading to a frictional electrical shielding effect on the surface of the LB film. This process reduces the surface charge density and weakens the frictional galvanic effect, which ultimately leads to a decrease in the output voltage.…”

“…When exposed to HCl atmosphere, the protons are transferred to the LB film and combined with NH 2 or N–H in the dye molecules, resulting in a protonation reaction that leads to a decrease in the concentration of pores in the film. As a result, the resistance of the film increases, thus increasing the Voc of the device . Subsequently, when the LB film was exposed to NH 3 , the reason for the decrease in Voc may be the occurrence of deprotonation leading to a frictional electrical shielding effect on the surface of the LB film.…”

Recent Progress of Flexible Photodetectors Based on Low‐Dimensional II–VI Semiconductors and Their Application in Wearable Electronics

“…As an alternative, TENGbased selfpowered technology has been proved to be an efficient strategy to satisfy the requirements of the electronics toward minimization, high integration, more intelligence etc. Although several efforts have been done on TENGbased selfpowered flexible electronics, there are still many challenges that need to be solved in future research, such as the stability of the output electric signals in mechanical energy harvesting process, [154] the integrated relia bility in systems, [155] the mechanical flexibility, [156] and the dura bility [157] of the integrated flexible electronics, etc. 4) Reliable safety and good biocompatibility.…”

A Self‐Powered, Rechargeable, and Wearable Hydrogel Patch for Wireless Gas Detection with Extraordinary Performance

“…To this end, self‐powered gas sensors have recently been proposed by integrating or coupling nanogenerators based on the triboelectric effect, photovoltaic (PV) effect, and thermoelectric effect with the sensor. [ 26–42 ] For example, Sun et al. have proposed a self‐powered NO 2 sensor driven directly by triboelectric nanogenerators (TENG) instead of traditional power supply.…”