Printed Capacitive Immunoassay for Detecting SARS-CoV-2 Viral Particles

The key to fight against a global pandemic such as COVID-19 is to have low-cost, reliable, and fast-response diagnostic tools. Electronic biosensors are preferred because of their ease of integration into current centralized healthcare networks and integration with modern point-of-care testing (POCT) devices. Printed electronic sensors provide a sensitive and reliable diagnostic platform to aid in controlling transmissible diseases. In this work, we demonstrate a fully printed capacitive biosensor. The sensor uses coplanar electrodes, coupled with capture antibodies immobilized on microporous polyvinylidene-fluoride (PVDF) films to detect the SARS-CoV-2 spike protein in spiked buffer solutions. Antibody immobilization on the PVDF surface is confirmed with confocal fluorescent imaging microscopy. Gold nanoparticle (GNP)-tagged detection antibodies are also introduced to provide increased sensitivity. The GNPs provide a reflectance layer that leads to increased capacitance. This increased capacitance can be measured directly and has demonstrated the ability to screen for spiked samples with statistical significance. This fully printed capacitive immunoassay has the potential to be used as a transmissible disease screening and vaccine efficacy assessment tool for resource-limited areas.