Integrated Opto-Acoustofluidic Sorter with Data-Efficient Digital Photon Counting

Fluorescence-activated cell sorting (FACS) is fundamental for single-cell analysis, but conventional systems often require free-space optical alignment and high-rate analog acquisition. Here, we present an integrated acoustofluidic sorter that combines focused traveling surface acoustic wave (FTSAW) actuation, an on-chip fiber-optic interface, and event-level digital photon counting. By operating at a 10 kHz sampling frequency, our software-defined acquisition scheme substantially reduces the real-time data burden compared to analog reconstruction methods, all while maintaining a high signal-to-noise ratio exceeding 23 dB. The system achieves 93.8% purity for sorting fluorescent microspheres at a theoretical throughput of up to 2 kHz. Furthermore, we demonstrated its practical utility by separating Haematococcus pluvialis from Chlorella vulgaris with 92.6% purity, while preserving high membrane integrity and short-term metabolic activity. By integrating the optical fibers into the chip and using photon-counting acquisition, the system reduces optical alignment requirements and lowers the acquisition burden for sorting control. These features may provide a practical basis for developing compact and easier-to-operate single-cell analysis platforms.