Field-Effect Control of Electroosmotic Pumping Using Porous SiliconaSilicon Nitride Membranes

Field-effect control of electroosmotic (EO) flow, which has been demonstrated on single microchannels, provides a novel method to modulate the zeta potential and, therefore, the EO flow through a porous membrane. To realize field-effect control of EO pumping with a membrane, a SiN sub(x)-coated poro...

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Bibliographic Details
Published in:Journal of microelectromechanical systems 2009-01, Vol.18 (6)
Main Authors: Vajandar, S K, Xu, Dongyan, Sun, Jiashu, Markov, DA, Hofmeister, W H, Li, Deyu
Format: Article
Language:English
Subjects:
Bias
Channels
Electric fields
Electric potential
Gates
Membranes
Pumping
Zeta potential
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Summary:Field-effect control of electroosmotic (EO) flow, which has been demonstrated on single microchannels, provides a novel method to modulate the zeta potential and, therefore, the EO flow through a porous membrane. To realize field-effect control of EO pumping with a membrane, a SiN sub(x)-coated porous silicon membrane was designed and fabricated. The heavily doped silicon core was used as a conducting electrode to apply the transverse gate potential, which modulates the zeta potential of the channel walls and, thereby, the EO flow rate with constant externally applied electric fields along the channels. We observed significant electrolytic-rectification effect, i.e., for gate voltage (V sub(g)) 0. Significant EO flow control, nearly 70% reduction in flow velocity, was observed for positive gate bias, while only 15 % flow-velocity enhancement was observed for negative gate bias of similar magnitude. This first demonstration of field-effect control on porous membranes opens the door for making high-flow rate EO pumps with porous membranes of low zeta potential materials.
ISSN:1057-7157
DOI:10.1109/JMEMS.2009.2031692