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Biocompatible bonding of a rigid off-stoichiometry thiol-ene-epoxy polymer microfluidic cartridge to a biofunctionalized silicon biosensor

Abstract

Attachment of biorecognition molecules prior to microfluidic packaging is advantageous for many silicon biosensor-based lab-on-a-chip (LOC) devices. This necessitates biocompatible bonding of the microfluidic cartridge, which, due to thermal or chemical incompatibility, excludes standard microfabrication bonding techniques. Here, we demonstrate a novel processing approach for a commercially available, two-step curable polymer to obtain biocompatible ultraviolet initiated (UVA)-bonding of polymer microfluidics to silicon biosensors. Biocompatibility is assessed by UVA-bonding to antibody-functionalized ring resonator sensors and performing antigen capture assays while optically monitoring the sensor response. The assessments indicate normal biological function of the antibodies after UVA-bonding with selective binding to the target antigen. The bonding strength between polymer and silicon chips (non-biofunctionalized and biofunctionalized) is determined in terms of static liquid pressure. Polymer microfluidic cartridges are stored for more than 18 weeks between cartridge molding and cartridge-to-silicon bonding. All bonded devices withstand more than 2500 mbar pressure, far exceeding the typical requirements for LOC applications, while they may also be de-bonded after use. We suggest that these characteristics arise from bonding mainly through intermolecular forces, with a large extent of hydrogen bonds. Dimensional fidelity assessed by microscopy imaging shows less than 2% shrinkage through the molding process and the water contact angle is approximately 80°. As there is generally little absorption of UVA light (365 nm) in proteins and nucleic acids, this UVA-bonding procedure should be applicable for packaging a wide variety of biosensors into lab-on-a-chip systems.
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Category

Academic article

Language

English

Author(s)

Affiliation

  • SINTEF Digital / Smart Sensors and Microsystems
  • Norwegian University of Science and Technology

Year

2022

Published in

Journal of Micromechanics and Microengineering (JMM)

ISSN

0960-1317

Volume

32

Issue

7

View this publication at Norwegian Research Information Repository