Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan.
Lab Chip. 2012 Oct 21;12(20):3943-51. doi: 10.1039/c2lc40436b.
Microfluidic technology plays an essential role in various lab on a chip devices due to its desired advantages. An automated microfluidic system integrated with actuators and sensors can further achieve better controllability. A number of microfluidic actuation schemes have been well developed. In contrast, most of the existing sensing methods still heavily rely on optical observations and external transducers, which have drawbacks including: costly instrumentation, professional operation, tedious interfacing, and difficulties of scaling up and further signal processing. This paper reports the concept of electrofluidic circuits - electrical circuits which are constructed using ionic liquid (IL)-filled fluidic channels. The developed electrofluidic circuits can be fabricated using a well-developed multi-layer soft lithography (MSL) process with polydimethylsiloxane (PDMS) microfluidic channels. Electrofluidic circuits allow seamless integration of pressure sensors with analog and digital operation functions into microfluidic systems and provide electrical readouts for further signal processing. In the experiments, the analog operation device is constructed based on electrofluidic Wheatstone bridge circuits with electrical outputs of the addition and subtraction results of the applied pressures. The digital operation (AND, OR, and XOR) devices are constructed using the electrofluidic pressure controlled switches, and output electrical signals of digital operations of the applied pressures. The experimental results demonstrate the designed functions for analog and digital operations of applied pressures are successfully achieved using the developed electrofluidic circuits, making them promising to develop integrated microfluidic systems with capabilities of precise pressure monitoring and further feedback control for advanced lab on a chip applications.
微流控技术因其所需的优势在各种芯片实验室设备中起着至关重要的作用。与执行器和传感器集成的自动化微流控系统可以进一步实现更好的可控性。已经开发出许多微流控致动方案。相比之下，大多数现有的传感方法仍然严重依赖于光学观察和外部换能器，这些方法存在以下缺点：仪器成本高、专业操作、繁琐的接口以及难以扩展和进一步进行信号处理。本文报告了电流体电路的概念 - 使用离子液体 (IL) 填充的流体通道构建的电路。所开发的电流体电路可以使用经过充分开发的多层软光刻 (MSL) 工艺与聚二甲基硅氧烷 (PDMS) 微流体通道制造。电流体电路允许将压力传感器与模拟和数字操作功能无缝集成到微流体系统中，并提供电读出信号以进行进一步的信号处理。在实验中，基于电流体惠斯通电桥电路构建模拟运算器件，该电路具有施加压力的加和减的电输出结果。数字运算（与、或和异或）器件使用电流体压力控制开关构建，并输出施加压力的数字运算的电信号。实验结果表明，使用所开发的电流体电路成功实现了对施加压力的模拟和数字运算的设计功能，这使得它们有望开发出具有精确压力监测和进一步反馈控制能力的集成微流体系统，用于先进的芯片实验室应用。
