IEEE Trans Biomed Circuits Syst. 2017 Dec;11(6):1488-1499. doi: 10.1109/TBCAS.2017.2766210.
Flow-based microfluidic biochips are attracting increasing attention with successful biomedical applications. One critical issue with flow-based microfluidic biochips is the large number of microvalves that require peripheral control pins. Even using the broadcasting addressing scheme, i.e., one control pin controls multiple microvalves simultaneously, thousands of microvalves would still require hundreds of control prins, which is unrealistic. To address this critical challenge in control scalability, the control-layer multiplexer is introduced to effectively reduce the number of control pins into log scale of the number of microvalves. There are two practical design issues with the control-layer multiplexer: (1) the reliability issue caused by the frequent control-valve switching, and (2) the pressure degradation problem caused by the control-valve switching without pressure refreshing from the pressure source. This paper addresses these two design issues by the proposed Hamming-distance-based switching sequence optimization method and the XOR-based pressure refreshing method. Simulation results demonstrate the effectiveness and efficiency of the proposed methods with an average 77.2% (maximum 89.6%) improvement in total pressure refreshing cost, and an average 88.5% (maximum 90.0%) improvement in pressure deviation.
基于流控的微流控生物芯片因其在生物医学领域的成功应用而受到越来越多的关注。基于流控的微流控生物芯片的一个关键问题是需要大量的微阀，这些微阀需要外围控制引脚。即使使用广播寻址方案，即一个控制引脚同时控制多个微阀，数千个微阀仍需要数百个控制引脚，这是不切实际的。为了解决控制可扩展性方面的这一关键挑战，引入了控制层多路复用器，以将控制引脚的数量有效地减少到微阀数量的对数级。控制层多路复用器存在两个实际设计问题：（1）频繁的控制阀切换导致的可靠性问题，以及（2）控制阀切换而没有来自压力源的压力刷新导致的压力降级问题。本文通过提出的基于汉明距离的切换序列优化方法和基于异或的压力刷新方法来解决这两个设计问题。仿真结果表明，所提出的方法具有有效性和高效率，总压力刷新成本平均提高了 77.2%（最高提高了 89.6%），压力偏差平均提高了 88.5%（最高提高了 90.0%）。
