High-sensitivity cytometric detection using fluidic-photonic integrated circuits with array waveguides

We demonstrate a new detection scheme for a micro-fabricated flow cytometer. The fluidic-photonic integrated circuits (FPICs) that perform flow cytometric detection possess new functionality, such as on-chip excitation, time-of-flight measurement, and above all, greatly enhanced fluorescence detection sensitivity. Using the architecture of space-division waveguide demultiplexer and the technique of cross-correlation analysis, we obtained high detection sensitivity with a simple light source and a detector, without high-power laser excitation and lock-in amplifier (or photomultiplier tube) detection. Besides improving cytometric detection, the technology of integrating microfluidic circuits with photonic circuits into the FPIC presents a new platform for sophisticated biomedical-sensing devices with significant cost, size, and performance advantages.