This paper presents a digital microfluidic (DMF) platform based on a printed circuit board (PCB) for droplet mixing. Mixing droplets without a top cover plate is important for bio-chemical analysis. For this reason, a more efficient mixing method is required especially for mixing a viscous liquid droplet in an open surface. Here, to improve the performance of droplet mixing, we propose the integration of an acoustically oscillating bubble to an electrowetting-on-dielectric (EWOD) chip, which can generate microstreaming inside the droplet. Firstly, an EWOD chip integrated with through-holes for bubble trapping was designed and fabricated through PCB fabrication. This PCB manufacturing technology helps to place more electrodes in the limited chip size. Secondly, we developed the custom-made circuit and interface to individually control multiple actuators (including EWOD actuation and acoustic excitation). Finally, an operation test was conducted to evaluate the capability of not only droplet transportation but also mixing on an open surface. The proposed PCB-based DMF platform for bubble-induced droplet mixing was experimentally verified and expected to make DMF chips more efficient when used for clinical point-of-care diagnostic applications.

中文翻译：

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基于 PCB 的数字微流体平台，用于在开放表面上混合液滴

本文提出了一种基于印刷电路板（PCB）的数字微流体（DMF）平台，用于液滴混合。在没有顶盖板的情况下混合液滴对于生化分析非常重要。因此，特别是对于在开放表面中混合粘性液滴而言，需要更有效的混合方法。在这里，为了提高液滴混合的性能，我们建议将声振荡气泡集成到电介质电润湿（EWOD）芯片中，该芯片可以在液滴内部产生微流。首先，通过PCB制造设计并制造了集成有用于捕获气泡的通孔的EWOD芯片。这种PCB制造技术有助于在有限的芯片尺寸内放置更多的电极。其次，我们开发了定制电路和接口来单独控制多个执行器（包括 EWOD 驱动和声学激励）。最后，进行了操作测试，以评估液滴传输和在开放表面上混合的能力。所提出的用于气泡诱导液滴混合的基于 PCB 的 DMF 平台经过实验验证，预计将使 DMF 芯片在用于临床护理点诊断应用时更加高效。