Static droplet array (SDA) is a pivotal tool for high-capacity screening assays, yet extraction and collection the target droplets that contain unique analytes or cells from the SDA remains one major technical bottleneck that limits its broader application. Here we present an optical-based on-demand droplet release (OODR) system by incorporating a 1064 nm laser-responsive indium tin oxide (ITO) layer into a chamber array-based droplet microfluidic chip. By focusing the 1064 nm laser onto the ITO layer, microbubbles can be created via local heating to selectively push-out the droplets from the chamber. Then the released droplet is readily exported in a one-droplet-one-tube (ODOT) manner by the inherent capillary force into pipette tip. Releasing of the droplets containing fluorescein sodium demonstrated ∼100% successful rate (9 out of 6400 droplets were successfully released) and low residual (only ∼5% of the droplet volume remains in the chamber). White or fluorescence image-based releasing of single-cell-droplets directly after cell loading or multi-cells-droplets derived from on-chip single-cell cultivation for both E. coli and yeast cells further demonstrated the wide applicability of OODR. The present system is user-friendly and has the potential to be applied in various high-throughput screening assays, including single molecule/cell analysis, drug screening, and phenotype-based cell sorting.

静态液滴阵列 (SDA) 是高容量筛选分析的关键工具，但从 SDA 中提取和收集含有独特分析物或细胞的目标液滴仍然是限制其更广泛应用的主要技术瓶颈。在这里，我们提出了一种基于光学的按需液滴释放 (OODR) 系统，该系统将 1064 nm 激光响应氧化铟锡 (ITO) 层合并到基于腔室阵列的液滴微流控芯片中。通过将 1064 nm 激光聚焦到 ITO 层上，可以通过局部加热产生微泡，从而选择性地将液滴推出腔室。然后，通过固有的毛细管力，释放的液滴很容易以一滴一管（ODOT）的方式导出到移液器吸头中。含有荧光素钠的液滴的释放显示出约 100% 的成功率（6400 个液滴中的 9 个被成功释放）和低残留（仅约 5% 的液滴体积保留在腔室中）。细胞加载后直接基于白色或荧光图像释放单细胞液滴，或者从大肠杆菌和酵母细胞的片上单细胞培养中产生多细胞液滴，进一步证明了 OODR 的广泛适用性。本系统用户友好，有潜力应用于各种高通量筛选测定，包括单分子/细胞分析、药物筛选和基于表型的细胞分选。