Towards a monolithically integrated microsystem based on the green tape ceramics technology for spectrophotometric measurements. Determination of chromium (VI) in water

A general procedure is presented for the fabrication of miniaturized continuous flow analytical microsystems based on photometric detection using the low temperature co-fired ceramics technology. Optical elements such as light emitting diodes and photodiodes (all in the size of a few hundred micrometers) are integrated by means of an off-chip approach. A simple procedure is demonstrated to integrate a glass window after the ceramic sintering in order to minimize the decrease in sensitivity due to the reduction of the optical path length when scaling down. A flow cell with a shape of a bubble has been used to increase the area of the light beam. The device is robust, affordable, and small-sized. It enables absorbance measurements to be performed in-situ or for continuous monitoring of environmental samples. Specifically, a microsystem is introduced for colorimetric determination of chromium (VI) ion in waters based on the diphenylcarbazide reagent as a model. Under the optimized conditions, a linear response is obtained for the concentration range from 0.1 to 20 mg L-1, with a detection limit of 50 μg L-1.