TITLE

An electro-osmotic micro-pump based on monolithic silica for micro-flow analyses and electro-sprays

AUTHOR(S)
Zilin Chen; Ping Wang; Chang, Hsueh-Chia
PUB. DATE
June 2005
SOURCE
Analytical & Bioanalytical Chemistry;Jun2005, Vol. 382 Issue 3, p817
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
A high-pressure electro-osmotic micro-pump fabricated by a sol-gel process is reported as a fluid-driving unit in a flow-injection analysis (FIA) system. The micro FIA system consists of a monolithic micro-pump on a glass slide (2.5×7.5 cm), a micro-injector, and a micro-sensor (2.5×1.5 cm). The monolithic silica matrix has a continuous skeleton morphology with micrometer-sized through-pores. The micrometer-size pores with a large negative surface charge density build up a large pressure under a DC electric field to drive fluid through the downstream units. A novel Nafion joint for the downstream cathode eliminates flow into the electrode reservoir and further enhances pressure build-up. The measured pump-pressure curve indicated a maximum pressure of 0.4 MPa at flow rate of 0.4 µL min-1 at 6 kV. Despite the large voltage, the small current transmission area through the monolith produced a negligible current (less than 100 µA) that did not generate bubbles or ion contaminants. The flow rate can be precisely controlled in the range 200 nL to 2.5 µL min-1 by varying the voltage from 1 to 6 kV. The high pump pressure and the large current-free DC field also enabled the pump to act as an electro-spray interface with a downstream analytical instrument.
ACCESSION #
17211501

 

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