Time-Resolved fluorescence measurement system for real-time high-throughput microfluidic droplet sorting

This work presents a Fluorescence Life-Time (FLT) measurement system for real-time microfluidic droplet sorting in high throughput conditions. This system is implemented using a low cost System-on-Chip (SoC) Field-Programmable Gate Array (FPGA) platform, that combines a Cyclone V FPGA with a dual-core ARM Cortex-a9 Hard Processor System (HPS). A time-correlated single photon counting system is implemented in the FPGA part and the data are transferred to the SDRAM of the HPS part to be processed by a developed bare-metal C program to extract the FLT of each droplet passing through the detection spot. According to the droplet's measured FLT, an action could be taken to sort this droplet. The system automatically detects the droplets and extracts their FLT values at different simulated droplet flow rates; from a few droplets up to 1 thousand droplets per second. Thanks to the use of a maximum Likelihood-based algorithm, the standard deviation of the measured FLTs of simulated droplets of the same material is only 30% above the theoretical quantum photon shot noise limit.