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Journal of Micro/Nanolithography, MEMS, and MOEMS

Capillary-driven microfluidic chips with evaporation-induced flow control and dielectrophoretic microbead trapping
Author(s): Yuksel Temiz; Jelena Skorucak; Emmanuel Delamarche
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Paper Abstract

This work reports our efforts on developing simple-to-use microfluidic devices for point-of-care diagnostic applications with recent extensions that include the trapping of microbeads using dielectrophoresis (DEP) and the modulation of the liquid flow using integrated microheaters. DEP serves the purpose of trapping microbeads coated with receptors and analytes for detection of a fluorescent signal. The microheater is actuated once the chip is filled by capillarity, creating an evaporation-induced flow tuned according to assay conditions. The chips are composed of a glass substrate patterned with 50-nm-thick Pd electrodes and microfluidic structures made using a 20-μm-thick dry-film resist (DFR). Chips are covered/sealed by low temperature (50°C) lamination of a 50-μm-thick DFR layer having excellent optical and mechanical properties. To separate cleaned and sealed chips from the wafer, we used an effective chip singulation technique which we informally call the “chip-olate” process. In the experimental section, we first studied dielectrophoretic trapping of 10-μm beads for flow rates ranging from 80  pL s−1 to 2.5  nL s−1 that are generated by an external syringe pump. Then, we characterized the embedded microheater in DFR-covered chips. Flow rates as high as 8  nL s−1 were generated by evaporation-induced flow when the heater was biased by 10 V, corresponding to 270-mW power. Finally, DEP-based trapping and fluorescent detection of functionalized beads were demonstrated as the flow was generated by evaporation-induced flow after the microfluidic structures were filled by capillarity.

Paper Details

Date Published: 23 September 2014
PDF: 7 pages
J. Micro/Nanolith. 13(3) 033018 doi: 10.1117/1.JMM.13.3.033018
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 13, Issue 3
Show Author Affiliations
Yuksel Temiz, IBM Research – Zürich (Switzerland)
Jelena Skorucak, IBM Research – Zürich (Switzerland)
Emmanuel Delamarche, IBM Research – Zürich (Switzerland)

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