ABSTRACT
Electrochemical biosensors are analytical devices that hold a current across the surface of an electrode on which biological receptors are immobilized. These devices enable the conversion of physio-biochemical reactions by biological molecules into electron movements, so the output can be observed as the flow of charge across the electrode. These biosensing platforms detect changes in the reactive and resistive properties of the electrode surface when an alternating current (AC) or voltage is applied to output signals. Impedance-based electrochemical biosensors have advantages compared with other biosensors, such as high sensitivity, low cost, and ease of operation. In addition to uses as miniature detection tools, biosensors and microfluidics play vital roles in nano-diagnostics. Many sensors have been developed at the nanoscale by exploiting the greater conductivity across the electrodes and improved specificity for biorecognition element-receptor binding in biosensing devices. Several of these sensors have been assessed in trials and emerged as clinical products for detecting and diagnosing diseases, bacteria, viruses, deficiencies, and biofluid malfunctions in the human body. This review summarizes advances in impedance-based biosensors and their working principles and classifications, as well as providing relevant illustrations by focusing on the essential biorecognition elements, receptors, and target molecules during diagnosis. Copyright © 2022 The Authors