Printed Electrochemical Biosensors: Opportunities and Metrological Challenges

Abstract

Printed electrochemical biosensors have recently gained increasing relevance in fields ranging from basic research to home-based point-of-care. Thus, they represent a unique opportunity to enable low-cost, fast, non-invasive and/or continuous monitoring of cells and biomolecules, exploiting their electrical properties. Printing technologies represent powerful tools to combine simpler and more customizable fabrication of biosensors with high resolution, miniaturization and integration with more complex microfluidic and electronics systems. The metrological aspects of those biosensors, such as sensitivity, repeatability and stability, represent very challenging aspects that are required for the assessment of the sensor itself. This review provides an overview of the opportunities of printed electrochemical biosensors in terms of transducing principles, metrological characteristics and the enlargement of the application field. A critical discussion on metrological challenges is then provided, deepening our understanding of the most promising trends in order to overcome them: printed nanostructures to improve the limit of detection, sensitivity and repeatability; printing strategies to improve organic biosensor integration in biological environments; emerging printing methods for non-conventional substrates; microfluidic dispensing to improve repeatability. Finally, an up-to-date analysis of the most recent examples of printed electrochemical biosensors for the main classes of target analytes (live cells, nucleic acids, proteins, metabolites and electrolytes) is reported.

Paper-Based Screen-Printed Electrodes: A New Generation of Low-Cost Electroanalytical Platforms

“…Notwithstanding the above, the commercialization of these devices continues to be a challenge since the knowledge transfer from laboratories to the society is still complicated. Although general printed electrochemical devices represent a unique opportunity to enable low-cost, fast, non-invasive and/or continuous monitoring of analytes, metrological aspects such as sensitivity, repeatability and stability represent very challenging aspects [ 190 ]. It is important to note that, in the laboratory, many of the fabrication and assembling steps are handmade, which affects the precision.…”

Glycated Hemoglobin and Methods for Its Point of Care Testing

“…The use of instrumentation would make the lateral flow immunochromatographic assay more applicable for diabetes mellitus, but this also creates material demands on equipment and limits the ability to perform the lateral flow immunochromatographic assay in point-of-care conditions. In addition to the standard lateral flow tests, various microfluidic devices have become popular and applicable in practice [ 76 , 77 , 78 , 79 ].…”

Electrochemical Nanobiosensors as Point‐of‐Care Testing Solution to Cytokines Measurement Limitations

“…Besides the selectivity, antifouling materials also help to face other important metrological variables for SPE‐based cytokines measurement as repeatability and stability [111]. Nonspecific (protein) adsorption (fouling) or binding (NSB) over WE are usually avoided by the use of bovine serum albumin (BSA) in most of here detailed SPEs and other similar platforms for cytokine biosensing (Table 1).…”

“…These properties should be optimally covered by electrochemical nanobiosensors for cytokine testing at the bedside, like those SPE‐based, which do not require a conventional lab infrastructure. Ideal cytokine electrochemical nanobiosensors must accomplish several technological dispositions to be in line with the ASSURED criteria [111, 169]: (i) Selectivity, a feature derived from the affinity and specificity conferred by the biorecognition element, which implies very low detection limit and low interferences (e. g., anti‐biofouling), respectively. (ii) Metrologically defined as the calibration plot‘s slope (i. e., output/input signals), the sensitivity is crucial for useful cytokine biosensing (few ml pg −1 or ml fg −1 ideally).…”