An AC Electro-osmosis Micropump
Date Issued
2005
Date
2005
Author(s)
Chen, Yu-An
DOI
en-US
Abstract
ABSTRACT
Pumping of electrolyte solution in micro scale, by planar asymmetric electrode array, based on AC electro-osmosis (ACEO) is reported in this thesis. The principle of ACEO flow is attributed to interaction between the component of electric field parallels the electrode surface and ions adjacent to the electrodes. Based on theoretical analysis proposed by Ramos et al. [7], distribution of flow velocity on electrode surface is calculated. Numerical results show that pumping can be achieved by asymmetry electrode geometry. Experimentally, the microfluidic chip is fabricated by electron beam evaporation, with Au/Cr on glass substrate, for the electrode array and replica molding via soft lithographic technique for the micro-channel. Total of 67 pairs of asymmetric electrode array to pump KCl solution (10-4M) are demonstrated.
Results show that pumping direction can be controlled by tuning the excitation voltage (1 to 9 volts peak to peak), and/or frequency (100Hz to 100kHz). Higher voltage, and/or frequency, results in pumping direction from wide to narrow electrode – indicative of faradaic process. Conversely, non-faradaic process occurs with lower voltage and/or frequency, which causes reversal in pumping direction and is attributed to electrical double layer forming on electrode surfaces. Maximum pumping velocity is over 20μm/sec for both faradaic and non-faradaic processes. In addition, transitional potential that causes a change in pumping direction is observed under a fixed frequency of 1kHz.
Pumping of electrolyte solution in micro scale, by planar asymmetric electrode array, based on AC electro-osmosis (ACEO) is reported in this thesis. The principle of ACEO flow is attributed to interaction between the component of electric field parallels the electrode surface and ions adjacent to the electrodes. Based on theoretical analysis proposed by Ramos et al. [7], distribution of flow velocity on electrode surface is calculated. Numerical results show that pumping can be achieved by asymmetry electrode geometry. Experimentally, the microfluidic chip is fabricated by electron beam evaporation, with Au/Cr on glass substrate, for the electrode array and replica molding via soft lithographic technique for the micro-channel. Total of 67 pairs of asymmetric electrode array to pump KCl solution (10-4M) are demonstrated.
Results show that pumping direction can be controlled by tuning the excitation voltage (1 to 9 volts peak to peak), and/or frequency (100Hz to 100kHz). Higher voltage, and/or frequency, results in pumping direction from wide to narrow electrode – indicative of faradaic process. Conversely, non-faradaic process occurs with lower voltage and/or frequency, which causes reversal in pumping direction and is attributed to electrical double layer forming on electrode surfaces. Maximum pumping velocity is over 20μm/sec for both faradaic and non-faradaic processes. In addition, transitional potential that causes a change in pumping direction is observed under a fixed frequency of 1kHz.
Subjects
交流電滲流
微幫浦
AC Electro-osmosis
micropump
PDMS
Type
thesis
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