Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

Richard Bruch; André Kling; Gerald A. Urban; Can Dincer

doi:10.3791/56105

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Method Article

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

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DOI:

10.3791/56105

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September 19th, 2017

Richard Bruch^*¹ , André Kling^*¹^,³ , Gerald A. Urban¹^,² , Can Dincer¹^,²

¹Department of Microsystems Engineering, University of Freiburg, ²Freiburg Materials Research Center, University of Freiburg, ³Department of Biosystems Science and Engineering, ETH Zurich

^* These authors contributed equally

Summary

A microfluidic biosensor platform was designed and fabricated using low-cost dry film photoresist technology for the rapid and sensitive quantification of various analytes. This single-use system allows for the electrochemical readout of on-chip-immobilized enzyme-linked assays by means of the stop-flow technique.

Abstract

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An easy-to-use and low-cost sensor platform is highly desired to measure various types of analytes (e.g., biomarkers, hormones, and drugs) quantitatively and specifically. For this reason, dry film photoresist technology - enabling cheap, facile, and high-throughput fabrication - was used to manufacture the microfluidic biosensor presented here. Depending on the bioassay used afterwards, the versatile platform is capable of detecting various types of biomolecules. For the fabrication of the device, platinum electrodes are structured on a flexible polyimide (PI) foil in the only clean-room process step. The PI foil serves as a substrate for the electrodes, which are insulated with an epoxy-based photoresist. The microfluidic channel is subsequently generated by the development and lamination of dry film photoresist (DFR) foils onto the PI wafer. By using a hydrophobic stopping barrier in the channel, the channel is separated into two specific areas: an immobilization section for the enzyme-linked assay and an electrochemical measurement cell for the amperometric signal readout.

The on-chip bioassay immobilization is performed by the adsorption of the biomolecules to the channel surface. The glucose oxidase enzyme is used as a transducer for electrochemical signal generation. In the presence of the substrate, glucose, hydrogen peroxide is produced, which is detected at the platinum working electrode. The stop-flow technique is applied to obtain signal amplification along with rapid detection. Different biomolecules can quantitatively be measured by means of the introduced microfluidic system, giving an indication of different types of diseases, or, in regard to therapeutic drug monitoring, facilitating a personalized therapy.

Introduction

Over the past two decades, diagnostic applications have become elementary for in-depth studies on the development of global public health. Traditionally, laboratory diagnostic tools are used for the detection of diseases. Even though they still play a key role in the diagnosis of diseases, point-of-care testing (POCT) performed near the patient or by the patient himself has become more and more commonplace in recent years. Especially in such cases that require immediate treatment, such as acute myocardial infarction or diabetes monitoring, the rapid confirmation of a clinical finding is essential. Hence, there is a growing need for POCT devices that can be operated by....