On-chip Raman spectrometers using narrow band filter array combined with CMOS image sensors

Recent advancements in nanotechnology raise the feasibility of a miniaturized, portable Raman spectrometer with promising applications such as material identification, food safety monitoring, and health care. Miniaturizing Raman spectrometers has remained a challenge owing to the inevitable weakness of Raman signals and the conflict between small size and spectral resolution. In this study, we present a portable mini-Raman spectrometer comprising a complementary metal–oxide semiconductor (CMOS) image sensor (CIS) integrated with an array of filter sets, a confocal probe, and a laser diode that successfully meets the miniaturization challenge. We also report successful measurement of Raman spectra using the CIS-based mini-spectrometer, measuring cyclohexane liquid, tylenol pills, and vitamin-C pills with high spectral resolution. Our mini-Raman spectrometer, which can measure Raman signals in a two-dimensional (2D) image format in a single-shot, can be embedded into commercial mobile phones and transformed into a promising Raman camera.