CMOS arrays as chemiluminescence detectors on microfluidic devices

A simple, low-cost process to integrate complementary metal oxide semiconductor array detectors (CMOSAD) for chemiluminescence is presented, evaluated, and applied to the determination of nitrite in ground water samples. CMOS arrays of different brands (obtained from commercial image sensors) were adapted as chemiluminescence detectors on microfluidic devices. The performance of the CMOSADs was evaluated in the visible zone of the spectrum using a tungsten halogen lamp as light source. Intrinsic parameters assessed included signal stability, spectral response, dark current, and signal-to-noise ratio. Thereafter, the CMOSADs were integrated on microfluidic devices and their performances in quantitative analysis were assessed with the chemiluminometric reaction of hydrogen peroxide with luminol, catalyzed with hexacyanoferrate (III). The parameters assessed were sensitivity, linear range, detection limit, reproducibility, correlation coefficient of the calibration curves, and baseline drift during measurements. The CMOSAD with the best performance was selected to assess the applicability of the developed microfluidic devices with the integrated detector. The microfluidic system permitted the determination of nitrite with both good precision and good recovery values in the analysis of ground water samples. Integration was easily achieved and enabled the development of a simple, low-cost, and feasible alternative to conventional detectors.