Development of an on-chip microfluidic system with filter-free multiple-wavelength sensor for microflow cytometry

This study aimed to report a compact microfluidic measurement system, based on a filter-free multiple-wavelength sensor, that can selectively identify wavelengths without using an optical component. Two types of fluorescent beads were successfully identified in the study using the proposed system. The sensor detected both wavelength and intensity of light using a potential peak formed by the photogate (PG) voltage. While conventional method detected only electrons moving toward the PG side and have to modulate the V-PG for wavelength measurement, our novel system focused on electrons moving toward the n-well side of the sensor as well. The wavelength was identified from the ratio of two currents, namely In-well and I-PG. Furthermore, wavelengths with different absorption characteristics could be identified based on the depth of the potential peak. The findings from this study may eventually be applied in the field of biology, including the quantitative and qualitative analyses of cells.