AC Electrokinetics-Enhanced Capacitive Virus Detection

Abstract

The occurrence and spread of various serious viral outbreaks in pandemic dimension is one of the few major threats to public health and life worldwide nowadays. A disease diagnosis method that is sufficiently sensitive, rapid, and compact for point-of-care (POC) detection, and requires minimal sample pretreatment is highly desired. Hence, developing such a detection method for POC detection of viral disease is of the utmost significance for medical healthcare. Among different types of biosensors, capacitive biosensors, which fall into the category of electroanalytical biosensors, stand out and have shown great success due to their excellent performances and high potential to be developed as easy-to-handle devices. Capacitive sensors reported for virus detection are a type of surface-based affinity sensors. Specific binding reactions occurring on the sensor surface will cause changes in the dielectric properties or thickness of the interfacial layer at the electrolyte-electrode interface. By measuring the sensor’s capacitance, the sensor can convert the quantity of target analytes, such as antigen, or nucleic acids from virus, or antibody from patient serum, into readable outputs.

This chapter firstly provides some background information on the significance of capacitive virus detection and briefly reviews the current status that scientists and researchers have accomplished in developing POC tests of viral disease (section “Introduction”). Section “Capacitive Biosensors” briefly presents various receptors that can be utilized and the sensing mechanism. Section “AC Electrokinetic (ACEK) Enrichment” introduces alternating current electrokinetic (ACEK) effects that can be incorporated into capacitive sensing. Last, sections “Sensor Designs” and “Sensor Performances” present sensor electrode characterization and sensor performances, respectively. Sensor characterization methods include equivalent circuit extraction and fitting with respect to the electrode cell’s impedance spectrum, electrodes surface treatment, and data acquisition and analysis. The discussion of sensor performance includes the optimization of buffer solutions, electrical signals, and sensor specificity, sensitivities, etc.