Researchers from Carnegie Mellon University and the University of Pittsburgh used aerosol jet 3D printing technology to develop one of the fastest COVID-19 diagnostics yet available. The microfluidic chip-based assay detects the presence of two of the antibodies to SARS-CoV-2, the virus responsible for COVID-19, and returns results in 10 to 15 seconds.
The test identifies the spike S1 protein and receptor binding domain in a drop of blood and detects 
The 3D-printed test platform interfaced with a portable potentiostat and connected to a smartphone. Source: Rahul Panat et al.antibody concentrations at levels as low as 0.15 ng/ml through an electrochemical reaction within a handheld microfluidic device. Results are transmitted to a simple interface on a smart phone, after which the device is disinfected within one minute using a special chemistry that allows multiple, successive readings from the same device.
Fabrication entails printing inexpensive gold micropillar electrodes at nanoscale by thermally sintering aerosol droplets together. This causes a rough, irregular surface that provides increased surface area of the micropillars and an enhanced electrochemical reaction, where antibodies can latch on to antigens coated on the electrode. The specific geometry allows the micropillars to load more proteins for detection, resulting in very accurate, quick results.
The test is reported to have a very low error rate as the binding reaction between the antibody and antigen used in the device is highly selective. The platform can also be used to gauge immune response in individuals, which could prove useful as COVID vaccines are made available and might also be applied to the detection of biomarkers for Ebola, HIV and other infectious agents.
The research is published in Advanced Materials.
