Integration of linear variable filters on CMOS for compact emission and absorption sensing

A compact optical spectrometer approach is presented that integrates multiple linear variable filters (LVFs) onto a CMOS imaging sensor for measurement of liquid-phase fluorescence and absorption that provides a 3.77-6.08 nm spectral resolution over a 400-1050 nm wavelength range. For fluorescence detection, we demonstrate detection limits of 0.28 nM for Quantum Dot emitters and 32 ng/mL for near-infrared fluorescent dyes. For colorimetric absorption detection, the system provides detection limits comparable to those obtained with a conventional spectrometer and a laboratory optical spectrum analyzer (OSA). As an exemplary application, we utilize the instrument for quantification of the concentration of chlorine in water.