Biosensing with Paper-Based Miniaturized Printed Electrodes-A Modern Trend

Abstract

From the bench-mark work on microfluidics from the Whitesides's group in 2007, paper technology has experienced significant growth, particularly regarding applications in biomedical research and clinical diagnostics. Besides the structural properties supporting microfluidics, other advantageous features of paper materials, including their versatility, disposability and low cost, show off the great potential for the development of advanced and eco-friendly analytical tools. Consequently, paper was quickly employed in the field of electrochemical sensors, being an ideal material for producing custom, tailored and miniaturized devices. Stencil-, inkjet-, or screen-printing are the preferential techniques for electrode manufacturing. Not surprisingly, we witnessed a rapid increase in the number of publications on paper based screen-printed sensors at the turn of the past decade. Among the sensing strategies, various biosensors, coupling electrochemical detectors with biomolecules, have been proposed. This work provides a critical review and a discussion on the future progress of paper technology in the context of miniaturized printed electrochemical biosensors.

Keywords: biosensors.; paper analytical device; printed electrodes; wax patterning.

Figure 1

Configurations of paper analytical devices used for electrochemical biosensing. RE–reference electrode, CE–counter electrode, WE–working electrode. Schemes were adapted from the following references: strip [24], folded [34], stack [40], paper disk [32].

Figure 2

Surface modification strategies of paper-based enzymatic biosensors: (a) inkjet-printed graphene–enzyme composite; (b) biomolecule drop cast over nanostructured layer; (c) biomolecule and redox mediator mixture drop casting; (d) screen-printed carbon–redox mediator composite with biomolecule drop casting; (e) biomolecule and redox mediator mixture drop casting over nanostructured layer.

Figure 3

Working principle of affinity biosensors based on sandwich-type assays coupled with electrochemical detection. S–enzymatic substrate, P–product, Med–redox mediator.