Satarkar Nitin S, Zhang Wenli, Eitel Richard E, Hilt J Zach
Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA.
Lab Chip. 2009 Jun 21;9(12):1773-9. doi: 10.1039/b822694f. Epub 2009 Mar 13.
In recent years, hydrogels have attracted attention as active components in microfluidic devices. Here, we present a demonstration of remote controlled flow regulation in a microfluidic device using a hydrogel nanocomposite valve. To create the nanocomposite hydrogel, magnetic nanoparticles were dispersed in temperature-responsive N-isopropylacrylamide (NIPAAm) hydrogels. The swelling and collapse of the resultant nanocomposite can be remotely controlled by application of an alternating magnetic field (AMF). A ceramic microfluidic device with Y-junction channels was fabricated using low temperature co-fired ceramic (LTCC) technology. The nanocomposite was incorporated as a valve in one of the channels of the device. An AMF of frequency 293 kHz was then applied to the device and ON-OFF control on flow was achieved. A pressure transducer was placed at the inlet of the channel and pressure measurements were done for multiple AMF ON-OFF cycles to evaluate the reproducibility of the valve. Furthermore, the effect of the hydrogel geometry on the response time was characterized by hydrogels with different dimensions. Magnetic hydrogel nanocomposite films of different thicknesses (0.5, 1, 1.5 mm) were subjected to AMF and the kinetics of collapse and recovery were studied.
近年来，水凝胶作为微流控装置中的活性成分受到关注。在此，我们展示了一种使用水凝胶纳米复合阀对微流控装置中的流动进行远程控制调节的方法。为了制备纳米复合水凝胶，将磁性纳米颗粒分散在温度响应性的N-异丙基丙烯酰胺（NIPAAm）水凝胶中。通过施加交变磁场（AMF）可以远程控制所得纳米复合材料的溶胀和收缩。使用低温共烧陶瓷（LTCC）技术制造了具有Y形通道的陶瓷微流控装置。将纳米复合材料作为阀并入该装置的其中一个通道中。然后将频率为293 kHz的AMF施加到该装置上，实现了对流动的开-关控制。在通道入口处放置一个压力传感器，并对多个AMF开-关循环进行压力测量，以评估阀的重现性。此外，通过使用不同尺寸的水凝胶来表征水凝胶几何形状对响应时间的影响。对不同厚度（0.5、1、1.5毫米）的磁性水凝胶纳米复合膜施加AMF，并研究其收缩和恢复的动力学。
