Design & Development of Laser Etched Porous-Silicon Capacitive Chip for Rapid Sensing of Pesticide Solvents

Abstract This work presents the development of porous silicon-based electrical sensor for the detection and quantification of organic solvents. The design of silicon chip is modeled as capacitive sensor. Different electrode configurations like coplanar top electrodes, top-bottom, coplanar bottom electrodes were analyzed in order to select optimum chip design for sensing application. The prototype chip was fabrication that used a mechanized pulse fiber laser etching process in order to develop a single-layer silicon structure with uniform porous structures. The fabricated chip was characterized using scanning electron microscopy and it shows an average pore diameter of 55.22 µm and pore depth of 98.9 µm. Organic solvents like ethanol, methanol, acetonitrile were tested and analyzed in order to investigate the performance of the proposed chip. Unlike porous silicon based optical sensors, the proposed sensor exhibited stable results up to 35 days at room temperature. The application of the proposed sensor chip is demonstrated for sensing and for the quantification of Atrazine chemical which is a pesticide solvent which is utilized in farming to control weeds. The sensitivity and the limit of detection was found to be 0.51 nF/ppm and 0.929 ppm respectively. The proposed capacitive-based porous silicon chip is suitable for time-effective and low-cost sensing and detection of organic solvents that are used in food industry.