Micro-Self-Assembly on Programmable Surfaces

Karl F. Bohringer, Ph.D.
MEMS Laboratory
Department of Electrical Engineering
University of Washington, Seattle

ABSTRACT:
In next generation microelectromechanical systems (MEMS), sensors and actuators will be integrated with electronic, optical, and fluidic components made from diverse materials onto a variety of substrates. Massively parallel micro self-assembly is an efficient, low-cost alternative to complex, monolithic fabrication processes or robotic pick-and-place microassembly.

We demonstrate a technique for assembly of multiple batches of micro components onto a single substrate. The assembly is driven by capillary force, which is created by droplets of hydrocarbon-based lubricant exclusively on hydrophobic sites on the substrate in an aqueous environment. In addition, an electrochemical approach for surface hydrophobicity modulation is adopted to alter the driving force, so as to control where the assembly takes place. Therefore, for each batch of identical micro components, desired sites on the substrate are modified to be hydrophobic and the micro components will be assembled to these hydrophobic sites. A key innovation is the ability to repeatedly apply this technique, which allows different batches of micro components to be organized onto the same substrate. Moreover, electroplating is incorporated into the technique as a post assembly procedure to establish electrical connections for the assembled components.

BIO:
Karl Bohringer is currently an assistant professor in Electrical Engineering with adjunct appointments in Mechanical Engineering and Computer Science & Engineering at the University of Washington, Seattle. He received both his M.S. and Ph.D. degrees in Computer Science from Cornell University and his Diplom-Informatiker degree from the University of Karlsruhe, Germany. During his dissertation work on distributed micromanipulation he designed, built, and tested multiple micro actuator arrays at the Cornell Nanofabrication Facility. He also spent a year as a visiting scholar at the Stanford Robotics Lab and Transducer Lab where he collaborated on research in MEMS distributed cilia arrays. From 1996 to 1998 he investigated techniques for parallel micro selfassembly at the University of California, Berkeley. His current interests include microelectromechanical systems (MEMS), micromanipulation and microassembly, and integrated biologically active microsystems. His Ph.D. thesis was nominated for the ACM doctoral dissertation award. He received an NSF postdoctoral associateship in 1997 and an NSF CAREER award in 1999.