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Published September 2008 | Published + Supplemental Material + Cover Image
Journal Article Open

Electronic control of elastomeric microfluidic circuits with shape memory actuators


Recently, sophisticated fluidic circuits with hundreds of independent valves have been built by using multi-layer soft-lithography to mold elastomers. However, this shrinking of microfluidic circuits has not been matched by a corresponding miniaturization of the actuation and interfacing elements that control the circuits; while the fluidic circuits are small (~10–100 micron wide channels), the Medusa's head-like interface, consisting of external pneumatic solenoids and tubing or mechanical pins to control each independent valve, is larger by one to four orders of magnitude (mm to cm). Consequently, the dream of using large scale integration in microfluidics for portable, high throughput applications has been stymied. By combining multi-layer soft-lithography with shape memory alloys (SMA), we demonstrate electronically activated microfluidic components such as valves, pumps, latches and multiplexers, that are assembled on printed circuit boards (PCBs). Thus, high density, electronically controlled microfluidic chips can be integrated alongside standard opto-electronic components on a PCB. Furthermore, we introduce the idea of microfluidic states, which are combinations of valve states, and analogous to instruction sets of integrated circuit (IC) microprocessors. Microfluidic states may be represented in hardware or software, and we propose a control architecture that results in logarithmic reduction of external control lines. These developments bring us closer to building microfluidic circuits that resemble electronic ICs both physically, as well as in their abstract model.

Additional Information

This journal is © The Royal Society of Chemistry 2008. Received 17th March 2008, Accepted 3rd June 2008. First published on the web 9th July 2008. The authors like to thank Anna Chetverikova, Christina Morales of the Caltech Microfluidic Foundry, Ali Ghaffari of the Micro/Nano Center, Caltech for assistance in fabrication; Lyn Hein and Kate Finigan for administrative support and Glenn George for advice on electronics. All of the authors wish to thank the Boeing Company for funding this project under the SRDMA program. Contributions: SV suggested the initial ideas and was involved with all subsequent ideas, designs and experiments, and wrote the paper. SS, SM, DA undertook several experiments, contributed to valve design and software programming, while being mentored by SV and AS. AS contributed ideas and helped write the paper. Electronic supplementary information (ESI) available: Movie showing in real time a 76 micron diameter wire being actuated using a 240 mA current. It is easy to visually determine that the channel is completely squeezed shut by the wire on actuation. See DOI: 10.1039/b804515a. The HTML version of this article has been enhanced with colour images.

Attached Files

Published - VYAloac08.pdf

Supplemental Material - VYAloac08.avi

Cover Image - VYAloac08.gif


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August 22, 2023
March 5, 2024