Patent name: Optical sensor system and sensing method based on attenuated total reflection

Technical field: The present invention relates to an optical sensor system based on attenuated total reflection (ATR), and more specifically, to a surface plasmon resonance based optical sensor system and a method for sensing Background technology: Sensors based on surface plasmon resonance (SPR) can be purchased in the market for research and development. For example, SI3R sensors can be purchased from GE Healthcare's BIAC0RE instrument product line in Uppsala, Sweden. These commercially available instruments use sensor glass chips, which are covered with a thin gold film carrying a fixed chemical sensor layer, as well as an integrated fluid box for allowing sample fluid and other fluids to pass through the sensor chip. The wedge-shaped beam is coupled to the sensor chip through a prism and a reusable optical interface to reflect the incident light from a certain angle range along a straight line at the glass/gold film interface, resulting in a total internal reflection (TIR) evanescent field at the glass/gold interface. At a unique narrow angle range of a specific wavelength, this TIR evanescent field transfers energy from incident light through the gold film and generates surface plasmon resonance at the interface of the gold film/sensor layer. The surface plasma wave generates an enhanced evanescent electric field, which has a characteristic penetration depth into the sample side of the gold surface, and thus the refractive index of the sample determines the angle of the sra. The 2D array of photodetectors detects the distribution of reflected light intensity by comparing the incident angle of a row of sensor light points along the irradiation line, in order to simultaneously generate SHU spectra for each sensor light point. When imaging multiple SHUs on a photodetector, the image has bright and dark bands. The sensor measures the angular position of dark bands generated on the detector surface through resonance coupling of reflected light and as surface plasma energy enters the gold film. The angular position of surface plasmon resonance depends on the refractive index of the sample penetrated by the SI ^ R evanescent field. The amount of reflected energy will also depend on the degree of absorption of evanescent field energy, just as the sample has a complex refractive index at a selected wavelength. The high sensitivity and resolution of SRA spectroscopy are expected, especially in the case of kinetic studies. In the field of high throughput biomolecular screening, high sensitivity is also expected for SI ^ R spectroscopy and other ATR spectroscopy methods. The sensitivity or resolution of the concave or peak (or in some cases multiple concave or peaks) or detectable changes in angle (or wavelength) at the centroid (center of mass) of the SRA reflection curve is mainly limited by the constancy, drift, and noise level of the background light intensity of the total internal reflection curve OlR curve. Ideally, the IlR curve is constant relative to the incident angle. However, in practice, due to the variation of reflection with incident angle and the distribution of radiation from the light source, the emitted beam spans the intensity profile, and thus the TIR curve is often a Gaussian curve with at least ー maximum values. Reflection may vary for various reasons, such as reflection loss in the optical coupling between prisms (or gratings) and plasma supported metals. A constant background intensity pattern can be normalized through suitable software algorithms. However, changing background images and/or significant corrections will introduce "normalization errors". Regardless of the type of algorithm used to calculate depressions, peaks, centroids (centers of mass), etc., the ATR spectral characteristics must be minimized in high-resolution ATR sensor instruments to minimize this "normalization error". The use of normalization for significant changes in intensity across the entire detector array results in a decrease in signal-to-noise ratio in lower intensity areas on the edge of the detector array