A 16-channel avalanche photodiode detector array for visible and near-infrared flow cytometry

Abstract

We report on the development and application of a flow cytometer using a 16-channel avalanche photodiode (APD) linear detector array. The array is configured with a dispersive grating to simultaneously record emission over a broad wavelength range using the 16 APD channels of the linear APD array. The APD detector elements have a peak quantum efficiency of 80% near 900 nm and have at least 40% quantum efficiency over the 400-nm to 1000-nm wavelength range. The extended red sensitivity of the detector array facilitates the use of lower energy excitation sources and near IR emitting dyes which reduces the impact of autofluorescence in signal starved measurements. The wide wavelength sensitivity of the APD array permits the use of multiple excitation sources and many different fluorescent labels to maximize the number of independent parameters in a given experiment. We show the sensitivity and linearity measurements for a single APD detector. Initial results for the flow cytometer with the 16-element APD array and the 16-channel readout ASIC (application specific integrated circuit) are presented.