Microfluidic-based Laser-Induced Graphene Sensors for Enhanced Electrochemical Immunoassay Performance

Diagnosing many human diseases is driven by the detection of one or more specific biomarkers. Rapid and sensitive detection of these biomarkers is crucial in preventing further illness and/or the spread of diseases within the individual and to other people. Microfluidic-based electrochemical immunoassays for biomarker detection have been explored as a practical alternative to time-consuming and expensive techniques such as polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), which require highly trained personnel. An important component in the fabrication of microfluidic devices is the electrode. Screen-printed carbon electrodes (SPCEs) are widely used due to their potential for mass production, and ease of printing directly onto the microfluidic device. Relatively recently, laser-induced graphene (LIG) has been used as an electrode material for electrochemical biosensors. LIG electrodes have excellent electrochemical properties like high conductivity and large surface area that make them superior to traditional SPCEs. However, although the incorporation of LIG electrodes into microfluidics has previously been demonstrated, this application has yet to be comprehensively explored. In this work, a simple method of incorporating LIG into microfluidics without harming electrode performance has been developed. The electrodes were subsequently characterized using various instrumental and electrochemical techniques. Furthermore, by tuning the geometry of both LIG electrodes and microfluidic devices, the advantages of this material can be exploited to create highly sensitive platforms for a variety of applications in the field. Future work involves the creation and execution of electrochemical immunoassays using LIG electrodes in a microfluidic device for use at the point-of-care.