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Open Access Publications from the University of California

Improving Assay Performance using Microfluidic Cavity Acoustic Transducers

  • Author(s): Nanayakkara, Imaly Anoshka
  • Advisor(s): Lee, Abraham P
  • et al.
Abstract

The development of an integrated immunoassay platform is crucial for providing diagnostic tools for global health applications. With the emergence of microfluidics, there is an increased focus in addressing this need. While many platforms have been created to successfully complete an immunoassay, they still require bulky external equipment to manipulate fluid within the device. Using technology developed in the BioMiNT lab, we've created an immunoassay platform that is capable of on-chip pumping and mixing with lateral and vertical-cavity acoustic transducer (LCAT & VCAT respectively) coupled to a piezoelectric transducer (PZT). PDMS devices were fabricated, molded and bonded to glass slides adhered with antigen-spotted nitrocellulose pads. Once they are primed with blocking buffer to introduce air bubbles, the devices are actuated with a PZT to drive fluid pumping and mixing. The reagents are pumped into the device serially and after completion, the spotted antigens on the pad become a dark purple hue, indicating an antibody-antigen binding event. For quantitative results, the intensities are evaluated using computer software. Results show that the resulting spot intensities are comparable to an established, optimized microarray platform in one-fifth of the time. We also show that these results cannot be reproduced in a passive or flow-through microfluidic device, indicating that convective mixing is necessary for improved signal intensity. Using the LCAT/VCAT platform, an immunoassay can be performed in 20 minutes and with increased sensitivity. Future work will involve expanding the device to allow for an automated point-of-care platform.

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