Applications of Graphene in Self-Powered Sensing Systems

Abstract

The advancements in the development of intelligent systems have resulted in an increase in the number, density, and distribution range of sensors. Traditional energy supply methods cannot meet the demands of the complex and variable sensor systems. However, the emergence of self-powered sensing devices that generate energy from their surroundings has provided a solution to this problem. Graphene, which has both an excellent sensing performance and wide range of applications in energy devices, facilitates the design of self-powered sensing systems. In recent years, several graphene-based self-powered sensors have been developed to overcome the design limitations of sensing systems. In this review, these sensors are divided into five categories according to their different energy conversion methods.(1) Self-powered by the electrochemical effect. The traditional electrochemical battery can be designed as a flexible structure that is responsive to external stimuli, including pressure, deformation, humidity, light, and temperature. It is an effective, stable, self-driving sensor, with working life determined by the amount of oxidizing/reducing agent present and the reaction rate. Flexible electrochemical cells with a high strain sensitivity ((I/I0)/ε = 124) and stretchability (2000%) have been achieved. (2) Self-powered by the photovoltaic effect. Graphene can form a Schottky junction when coupled with various semiconducting materials, such as Si, GaAs, MoS2, and some of their nanostructures. In these heterostructures, the van der Waals interface exhibits a Schottky barrier, which can separate photogenerated electron-hole pairs without external bias. Graphene-based Schottky junctions have been widely used as self-powered photodetectors with extremely high responsivities ( ~149 A•W −1 ). (3) Self-powered by the triboelectric effect. The contact and separation of two surfaces can result in the separation of charges due to the difference in electron affinities of the materials. This results in an induced electrostatic force between the electrodes, thereby driving the flow of electrons in an external circuit. Triboelectric nanogenerators can realize self-driving touch/pressure sensing and are used for several applications, including touch screens, neural finger skin, and electronic skin. (4) Self-powered by the hydrovoltaic effect. Graphene can interact with water at the solid-liquid interface and generate an electrical signal. Therefore, graphene-based hydrovoltaic devices can constitute very simple self-driving sensors that are efficient in determining fluid flow, solution concentration, and humidity, among others. (5) Self-powered by other effects, such as the thermoelectric effect, piezoelectric effect, or pyroelectric effect. Although the electrical signals generated by these effects are relatively weak, they can be used for some special applications, such as temperature or infrared sensors. Finally, we discuss the future developments, challenges, and prospects of graphene-based self-powered sensing devices and syste...

Facile synthesis of Ti3C2Tx@gold nanoparticle-arginine and serine-functionalized graphene quantum dot aerogel for electrochemical detection of chloramphenicol

“…However, CAP is still used illegally in agricultural production and aquaculture because of its low cost and high efficiency. 5 Some modern techniques, such as gas chromatography (GC), 6 gas chromatography-mass spectrometry, 7 high-performance liquid chromatography (HPLC), 8 liquid chromatography combined with mass spectrometry (LC-MS), 9 chemiluminescence, 10 enzymelinked immunosorbent assay (ELISA), 9 fluorescence method 8 and electrochemical sensors, 11 have been developed for the detection of CAP. LC-MS is the most commonly used method for the detection of CAP in the laboratory, but it needs expensive instrumentation, a well-trained workforce and complex sample treatment steps.…”