Droplet Rapid-Analasis Method of Metal-Salt Solution Based on Triboelectric Effect

Detection and analysis of metal-salt solution are significant in many areas, especially for environmental monitoring. However, the complicated procedure and specific equipment are necessary, which is difficult to realize on-site rapid detection. In resent years, the arising of triboelectric nanogenerator attracts more and more investigation. Herein, a novel compact sensor for rapid detection of metal-salt solution droplet based on triboelectrification was developed. The proposed sensor enables to sense fundamental motion state and intrinsic property of test droplets, such as the concentration, with nonlinear responses produced in form of triboelectric pulses. Furthermore, the printed circuit board (PCB) technology was adopted to print interdigital electrodes for cost-effective fabrication. A thin film of polytetrafluoroethylene (PTFE) layer was prepared to cover electrodes, serving as a negative charged material in triboelectrification effect. As a functional dielectric material, PTFE with transferred electrons constructs electrostatic field, while interdigital electrodes collect electrons due to the electrostatic induction changed by the movement of liquid droplets. Therefore, according to the relation between the electric output signal and the features of droplet, the molarity, volume and type of measured droplet can be semi-quantitatively figured out. Thus, this triboelectrification-based method provides a new path to carry out a rapid and on-site detection of metal-salt solution droplet, and show an attractive potential toward a low-cost, portable and repeatable application.