A simple means for weaving a hydrogel into a microdevice is presented. A glass plate is scored on both sides with trenches of depth slightly more than half the plate thickness. Trenches on the two faces of the wafer are perpendicular to each other, and integral holes are formed at the intersections between the perpendicular trenches. This crosscut microstructure is readily loaded with a hydrogel, which interlocks with the wafer. When the hydrogel is thermoresponsive in its swelling, the hydrogel crosscut construct (HyC) can be used for thermofluidic gating of flow perpendicular to the plate surface. A simple test rig to demonstrate this principle is constructed, and response times to changes in temperature are determined. An autonomous thermofluidic oscillator, which makes use of the HyC and functions by the coupled dissipation of thermal and hydraulic pressure gradients, is demonstrated.
Bibliographical noteFunding Information:
This work was support in part by NIH grant HD040366, and by a Samuel J. Melendy Fellowship to Y. Gu. Part of this work was carried out in the University of Minnesota Nanofabrication Center (MNFC), which receives partial support from NSF through the NNIN program.
Babak Ziaie received his Ph.D. in Electrical Engineering from the University of Michigan in 1994. From 1995 to 1999 he was a postdoctoral-fellow and assistant research scientist at the Center for Integrated Microsystems (CIMS) of the University of Michigan. He joined the Electrical and Computer Engineering Department of the University of Minnesota as an assistant professor. Since January 2005, he has been with the School of Electrical and Computer Engineering at Purdue University where he is an associate professor. His research interests are related to BioMEMS, including include implantable wireless microsystems, smart polymers for physiological sensing and active flow control, micromachined interfaces with the central nervous system, biomimetic sensors and actuators, and ultra-sensitive sensors for biological (molecular and cellular) applications. Dr. Ziaie received an NSF Career award in Biomedical Engineering (2001) and a McKnight Endowment Fund Award for Technological Innovations in Neuroscience (2002). Dr. Ziaie is a member of the IEEE and the American Association for the Advancement of Science.