Monodisperse picoliter droplets have been widely used for biochemical reactors and preparation of functional microbeads for food, cosmetics, and medical industry. Although conventional microfluidic technologies enable the production of monodisperse picoliter droplets, special instruments (e.g. syringe pump) are required, leading to its poor usability and accessibility in other research fields. In this study, we propose centrifuge-based step emulsification device housed in a microtube for simple and fast generation of monodisperse picoliter droplets. Our device consists of a reservoir part for storage of the dispersed phase and a microchannel part for droplet formation. Centrifugation using a commercial centrifuge exerts excessive pressure on the dispersed phase, infusing it into a microchannel. The infused dispersed phase is pinched off, forming droplets due to the channel geometry for step emulsification. The produced droplets at the step then are transported to the bottom of the microtube due to the centrifugal force. Using this device, we achieved formation of monodisperse water-in-oil (W/O) picoliter droplets with diameters ranging from 18 to 90 μm. Moreover, we demonstrated the cell-free protein synthesis reaction in monodisperse picoliter droplets as well as the production of cell-sized glucose-responsive hydrogel microbeads. We believe that our device would be a powerful tool for simple and fast preparation of picoliter samples with high usability.

单分散皮升液滴已被广泛用于生化反应器以及食品，化妆品和医疗行业功能性微珠的制备。尽管常规的微流体技术可以产生单分散的微微升液滴，但仍需要特殊的仪器（例如注射泵），这导致其在其他研究领域的可用性和可及性很差。在这项研究中，我们建议将微离心管中的离心式乳化装置装在微管中，以简单，快速地产生单分散皮升液滴。我们的设备由一个用于分散相存储的容器部分和一个用于液滴形成的微通道部分组成。使用商用离心机进行的离心分离会对分散相施加过大的压力，从而将其注入微通道。注入的分散相被夹断，由于用于分步乳化的通道几何形状而形成液滴。然后，由于离心力的作用，在该步骤产生的液滴被输送到微管的底部。使用该设备，我们实现了直径在18至90μm范围内的单分散油包水（W / O）皮升液滴的形成。此外，我们证明了单分散皮升液滴中的无细胞蛋白质合成反应以及细胞大小的葡萄糖反应性水凝胶微珠的产生。我们相信，我们的设备将是用于简单且快速地制备具有高可用性的皮升样品的强大工具。我们实现了直径在18至90μm范围内的单分散油包水（W / O）皮升液滴的形成。此外，我们证明了单分散皮升液滴中的无细胞蛋白质合成反应以及细胞大小的葡萄糖反应性水凝胶微珠的产生。我们相信，我们的设备将是用于简单且快速地制备具有高可用性的皮升样品的强大工具。我们实现了直径在18至90μm范围内的单分散油包水（W / O）皮升液滴的形成。此外，我们证明了单分散皮升液滴中的无细胞蛋白质合成反应以及细胞大小的葡萄糖反应性水凝胶微珠的产生。我们相信，我们的设备将是用于简单且快速地制备具有高可用性的皮升样品的强大工具。