Digital (i.e., droplet-based) microfluidics, by the electrowetting-on-dielectric (EWOD) mechanism, has shown great potential for a wide range of applications, such as lab-on-a-chip. While most reported EWOD chips use a series of electrode pads essentially in 1D line pattern designed for specific tasks, the desired universal chips allowing user-reconfigurable paths would require the electrode pads in 2D pattern. However, to electrically access the electrode pads independently, conductive lines need to be fabricated underneath the pads in multiple layers, raising a cost issue particularly for disposable chip applications. In this paper, we report the building of digital microfluidic plates based on a printed circuit board (PCB), in which multilayer electrical access lines were created inexpensively using the mature PCB technology. However, due to its surface topography and roughness and resulting high resistance against droplet movement, the as-fabricated PCB surfaces require high (~500 V) voltages unless coated with or immersed in oil. Our goal is the EWOD operations of droplets not only on oil-covered surfaces but also on dry ones. To meet the varying levels of performances, three types of gradually complex post-PCB microfabrication process are developed and evaluated. By introducing land-grid-array sockets in the packaging, a scalable digital microfluidic system with a reconfigurable and low-cost chip is also demonstrated.

中文翻译：

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使用多层印刷电路板的直接参考二维阵列数字微流体

通过电介质电润湿 (EWOD) 机制的数字（即基于液滴的）微流体已显示出在广泛应用中的巨大潜力，例如芯片实验室。虽然大多数报道的 EWOD 芯片使用一系列基本上为特定任务设计的 1D 线图案的电极垫，但允许用户重新配置路径的所需通用芯片将需要 2D 图案的电极垫。然而，为了独立地对电极焊盘进行电气访问，需要在焊盘下方以多层方式制造导电线，这增加了成本问题，尤其是对于一次性芯片应用而言。在本文中，我们报告了基于印刷电路板 (PCB) 的数字微流体板的构建，其中使用成熟的 PCB 技术廉价地创建了多层电气接入线。然而，由于其表面形貌和粗糙度以及由此产生的对液滴运动的高阻力，制造的 PCB 表面需要高 (~500 V) 电压，除非涂有油或浸在油中。我们的目标是不仅在油覆盖的表面上而且在干燥的表面上进行液滴的 EWOD 操作。为了满足不同水平的性能，开发和评估了三种逐渐复杂的 PCB 后微制造工艺。通过在包装中引入陆栅阵列插座，还展示了具有可重构和低成本芯片的可扩展数字微流体系统。我们的目标是不仅在油覆盖的表面上而且在干燥的表面上进行液滴的 EWOD 操作。为了满足不同水平的性能，开发和评估了三种逐渐复杂的 PCB 后微制造工艺。通过在包装中引入陆栅阵列插座，还展示了具有可重构和低成本芯片的可扩展数字微流体系统。我们的目标是不仅在油覆盖的表面上而且在干燥的表面上进行液滴的 EWOD 操作。为了满足不同水平的性能，开发和评估了三种逐渐复杂的 PCB 后微制造工艺。通过在包装中引入陆栅阵列插座，还展示了具有可重构和低成本芯片的可扩展数字微流体系统。