Departments of Bioengineering and Applied Physics, Stanford University and Howard Hughes Medical Institute, Stanford, California 94305, USA.
Lab Chip. 2013 May 21;13(10):1911-8. doi: 10.1039/c3lc41394b. Epub 2013 Mar 25.
Multilayer microfluidics based on PDMS (polydimethylsiloxane) soft lithography have offered parallelism and integration for biological and chemical sciences, where reduction in reaction volume and consistency of controlled variables across experiments translate into reduced cost, increased quantity and quality of data. One issue with push up or push down microfluidic control concept is the inability to provide multiple control pressures without adding more complex and expensive external pressure controls. We present here a microfluidic serial DAC (Digital to Analog Converter) that can be integrated with any PDMS device to expand the device's functionality by effectively adding an on-chip pressure regulator. The microfluidic serial DAC can be used with any incompressible fluids and operates in a similar fashion compared to an electronic serial DAC. It can be easily incorporated into any existing multilayer microfluidic devices, and the output pressure that the device generates could be held for extensive times. We explore in this paper various factors that affect resolution, speed, and linearity of the DAC output. As an application, we demonstrate microfluidic DAC's ability for on-chip manipulation of flow resistance when integrated with a simple flow network. In addition, we illustrate an added advantage of using the microfluidic serial DAC in preventing back flow and possible contamination.
基于 PDMS（聚二甲基硅氧烷）软光刻的多层微流控技术为生物和化学科学提供了并行性和集成性，其中反应体积的减少和实验中可控变量的一致性转化为成本的降低、数据数量和质量的提高。推挽式或推压式微流控控制概念的一个问题是，如果不添加更复杂和昂贵的外部压力控制，就无法提供多个控制压力。我们在这里提出了一种微流控串行 DAC（数字到模拟转换器），可以与任何 PDMS 设备集成，通过有效地添加片上压力调节器来扩展设备的功能。微流控串行 DAC 可与任何不可压缩流体一起使用，其工作方式与电子串行 DAC 类似。它可以很容易地集成到任何现有的多层微流控设备中，并且设备产生的输出压力可以保持很长时间。我们在本文中探讨了影响 DAC 输出分辨率、速度和线性度的各种因素。作为应用，我们展示了微流控 DAC 在与简单的流网络集成时，对芯片上流动阻力进行控制的能力。此外，我们还说明了在防止回流和可能的污染方面使用微流控串行 DAC 的一个额外优势。
