All-electronic droplet generation on-chip with real-time feedback control for EWOD digital microfluidics
All-electronic droplet generation on-chip with real-time feedback control for EWOD digital microfluidics
复制标题
DOI：
10.1039/b717417a
复制
发表时间：
2008-01-01
期刊：
影响因子：
6.1
通讯作者：
Kim, Chang-Jin (CJ)
中科院分区：
文献类型：
--
作者：
Gong, Jian;Kim, Chang-Jin (CJ)
电介质上电润湿（EWOD）致动实现了数字（或液滴）微流体，其中在二维表面上操纵小的液体包。由于其机械简单性和低能耗，EWOD对便携式系统特别有希望。为了提高液滴的体积精度，这对于诸如生物化学测定的定量应用是期望的，现有的实践将需要近乎完美的装置制造和操作条件，除非液滴是在通过离开芯片的额外泵设置的反馈控制下产生的。在本文中，我们开发了一个全电子（即，无辅助泵送）芯片上液滴产生的实时反馈控制。一个快速电压调制，电容传感，和离散时间PID反馈控制器集成在操作电子板。与开环控制以及采用外部泵的先前反馈控制相比，在液滴体积均匀性方面获得了显著改善。此外，这种新的能力使用户能够规定液滴体积，甚至低于先前考虑的最小值，允许例如1：x（x < 1）混合，与先前考虑的n：m混合（即，n和m单位液滴）。
Electrowetting-on-dielectric (EWOD) actuation enables digital ( or droplet) microfluidics where small packets of liquids are manipulated on a two-dimensional surface. Due to its mechanical simplicity and low energy consumption, EWOD holds particular promise for portable systems. To improve volume precision of the droplets, which is desired for quantitative applications such as biochemical assays, existing practices would require near-perfect device fabrication and operation conditions unless the droplets are generated under feedback control by an extra pump setup off of the chip. In this paper, we develop an all-electronic (i.e., no ancillary pumping) real-time feedback control of on-chip droplet generation. A fast voltage modulation, capacitance sensing, and discrete-time PID feedback controller are integrated on the operating electronic board. A significant improvement is obtained in the droplet volume uniformity, compared with an open loop control as well as the previous feedback control employing an external pump. Furthermore, this new capability empowers users to prescribe the droplet volume even below the previously considered minimum, allowing, for example, 1 : x (x < 1) mixing, in comparison to the previously considered n : m mixing (i.e., n and m unit droplets).