Dusty plasmas for on-site spectroscopic analysis of water sources

Abstract

ABSTRACT This paper reports on a low-cost, borosilicate glass-based spectroscopic sensor for the detection of water contaminants. 10 P L water samples are inserted into a sandblasted sample re servoir in a borosilicate glass substrate and are partially evaporated with a 200 nm thin-film Cr microheater/cathode patterned to the bottom of the reservoir. The relative contaminant concentration within the partially evaporated sample is greater, providing a means of measuring lower concentrations of impurities. An on-chip plasma discharge is stuck to the sample, sputtering the water contaminants into the discharge, doping its spectral emissions. Cu and Fe impurities are detected at 10 ppm in a 2.5% HNO 3 solution and Ca and Mg contaminants are detected at 100 ppm. The on-chip microheater yields temperature changes as high as 96 qC when supplied with 100 mA. Multiple single-use sensors can be fabricated inexpensively on the borosilicate glass substrate using simple, standard photolithography techniques. Keywords: plasma spectroscopy, atomic emission spectroscopy, on-site water monitoring, metal ion water contaminants, metal ion water impurities, field-portable devices