Portable image-based detection system for Upconverting phosphor immune lateral flow assay

A portable image-based detection system for Up-converting phosphor immune lateral flow assay is introduced. A commecial low light level CMOS sensor is chosen as the detector, which is low cost. The excitation light source is a 980nm and 500mw laser diode. In order to minish the error induced by the un-uniformity of laser irradiation, a diffuser is inserted into the beam and a calibration algorithm is developed. The residual error from the un-uniformity irradiation is less than 1%. Benefit from the adjustable of the exposure time, the integrated dynamic range of the system is as high as 106dB. The repeat test error for the very low signal is 1% (variation coefficient). And the linear correlation coefficient between the tested T/C value and sample concentration is 0.998. Compared to the traditional instrument, the detection system is static, low cost, portable and high-precision.