Fluorescence detection of submicromolar concentration using a filter-free fluorescence sensor

In this paper, the detection of fluorescence from the solution of a fluorescent dye with a submicromolar concentration by the filter-free fluorescence sensor is reported. The filter-free fluorescence sensor has a photo-gate structure and the intensities of excitation and fluorescent lights can be calculated from the photocurrents for different gate voltages. It makes it possible to measure various wavelengths even without optical filters and mirrors. The separation ability of excitation light (470 nm) and fluorescence (530 nm) in the developed filter-free fluorescence sensor was 1200:1 for LED light source. The fluorescent measurements were carried out for the dye of fluorescein isothiocyanate isomer. The excitation light with the wavelength of 470 nm was used, and the photocurrents were measured for the gate voltages of 1 V and 3 V, respectively. Based on the calculation, the fluorescence from fluorescein isothiocyanate isomer was detected for the solution with the concentration of as low as 100 nM (12 bases).