Single cell micro-absorption spectroscopy system with temperature control: System design and spectral analysis

Micro-absorption spectroscopy is a useful tool for studying the biological characteristics of single cells. However, the weak spectral signal, due to low absorption caused by the tiny optical path length of the cell, makes the spectral data noisy and difficult to analyze. This paper describes a device for single-cell microspectroscopy measurement that integrates an optical fiber spectrometer and an image CCD within a microscopic system, allowing for the simultaneous acquisition of morphology information and the absorption spectrum of a single cell. The device utilizes an illumination source driven by modulated current sources instead of constant current sources and the corresponding spectral signal extraction method to reduce noise levels. It also features a transparent temperature-controlled sample chamber for regulating the sample's temperature, as the absorption of cells may change with temperature. Due to the unwanted baseline drift in the spectral signals, a method of analyzing the similarity degree between the measured spectrum and the standard spectrum is proposed to study the characteristic variation of cells. To verify the feasibility of this method, the device was used for the microscopic spectral measurement and analysis of single red blood cells. The results showed that the variation patterns of spectral parameters correspond to the cell's responses to changes in temperature and storage duration.