Improvement of particle alignment control and precise image acquisition for on-chip high-speed imaging cell sorter

We have developed a real-time imaging cell sorting system composed of a micrometer-sized gel-electrode-embedded microfluidic sorting chip and a real-time image analysis/recognition unit equipped with a high-speed camera and image processing circuits. For the microfluidic continuous cell sorting, we have examined the precise position and velocity control of flowing particles and the precise acquisition of microscopic images of flowing particles. The results showed that (1) hydrodynamic focusing can line up particles precisely within a range of 5 μm particle size distribution, (2) active air pressure-driven flow velocity control can create the flow in the microfluidic pathways up to 160mm/s with 0.15MPa air pressure maintaining linear correlation between air pressure and flow velocity, and (3) 1μs flash illumination can prevent the blur even under 200mm/s flow. Applying the above elements into the system, the recognition error of target particles was within 5% for 2 μm particles with 2.5mm/s flow. The experimental results demonstrate the potential of the image index-based on-chip cell sorter for practical application.