Journal article
Impact of leakage current and electrolysis on FET flow control and pH changes in nanofluidic channels
Lab on a chip, Vol.9(11), pp.1609-1617
06/07/2009
Handle:
https://hdl.handle.net/2376/105375
PMCID: PMC2910628
PMID: 19458870
Abstract
We have fabricated multiple-internal-reflection Si infrared waveguides integrated with an array of nanochannels sealed with an optically transparent top cover. The channel walls consist of a thin layer of SiO
2
for electrical insulation, and gate electrodes surround the channel sidewalls and bottom to manipulate their surface charge and
ζ
-potential in a fluidic field effect transistor (FET) configuration. This nanofluidic device is used to probe the transport of charged molecules (Alexa 488) and to measure the pH shift in nanochannels in response to an electrical potential applied to the gate. During gate biasing for FET operation, laser-scanning confocal fluorescence microscopy (LS-CFM) is used to visualize the flow of fluorescent dye molecules (Alexa 488), and multiple internal reflection-Fourier transform infrared spectroscopy (MIR-FTIRS) is used to probe the characteristic vibrational modes of fluorescein pH indicator and measure the pH shift. The electroosmotic flow of Alexa 488 is accelerated in response to a negative gate bias, whereas its flow direction is reversed in response to a positive gate bias. We also measure that the pH of buffered electrolyte solutions shifts by as much as a pH unit upon applying the gate bias. With prolonged application of gate bias, however, we observe that the initial response in flow speed and direction as well as pH shift becomes reversed. We attribute these anomalous flow and pH shift characteristics to a leakage current that flows from the Si gate through the thermally grown SiO
2
to the electrolyte solution.
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Details
- Title
- Impact of leakage current and electrolysis on FET flow control and pH changes in nanofluidic channels
- Creators
- Youn-Jin Oh - Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico, 87131, USA. Fax: +1 277 5443; Tel: +1 277 3118Danny Bottenus - Department of Chemical Engineering, Washington State University, Pullman, WA, 99164, USACornelius F Ivory - Department of Chemical Engineering, Washington State University, Pullman, WA, 99164, USASang M Han - Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico, 87131, USA. Fax: +1 277 5443; Tel: +1 277 3118
- Publication Details
- Lab on a chip, Vol.9(11), pp.1609-1617
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Identifiers
- 99900546754101842
- Language
- English
- Resource Type
- Journal article