Integrated lab-on-a-chip devices: Fabrication methodologies, transduction system for sensing purposes

Lab-on-a-chip (LOC) biosensors have recently piqued the interest of the research community as a result of its potential utility in personal healthcare and disease diagnostics. LOCs devices have been consistently developed over the last decades as merging microfluidics onto a single chip for performing many lab studies at the same time, such as biochemical and biomolecular detection. Molding, microcontact printing, micromachining, and other techniques were used in the preliminary advancement of miniature sensing platforms known as micro total analysis systems (μTAS). These time-consuming and multi-step processes were utilized to create structures on a micrometer size. As time passes, new approaches and modifications for replacing rigid substrates with flexible substrates were developed. Over the years, paper and plastic substrates have shown unique properties such as durability, flexibility, mobility, cost-effective, and simple manufacturing procedure owing to their compatibility with a wide range of printing equipment. This review discusses the different types of fabrication methods and techniques such as photolithography, soft lithography, screen printing, inkjet printing, laser micromachining, nanoimprinting for designing LOC sensing devices extensively. The types of transduction systems which includes electrochemical, optical and mechanical that play an important role in sensing devices have also been extensively described in this manuscript. Additionally, detection of numerous analytes categorized into small molecules, macromolecules and cell bodies have been comprehensively reviewed in this manuscript with illustrations and tabulated form.