COVID-19 Test Chip Made by Aerosol Jet Nanoparticle 3D Printing Detects SARS-CoV-2 Antibodies in 10-12 Seconds

Antibody concentrations can be extremely low and still detected below one picomolar (0.15 nanograms per milliliter). This detection happens through an electrochemical reaction within a handheld microfluidic device which sends results almost immediately to a simple interface on a smart phone.

An additive manufacturing technology called aerosol jet 3D printing is responsible for the efficiency and accuracy of the testing platform. Tiny, inexpensive gold micropillar electrodes are printed at nanoscale using aerosol droplets that are thermally sintered 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 has a very low error rate because the binding reaction between the antibody and antigen used in the device is highly selective. The researchers were able to exploit this natural design to their advantage.

"We utilized the latest advances in materials and manufacturing such as nanoparticle 3D printing to create a device that rapidly detects COVID-19 antibodies," said Rahul Panat, an associate professor of mechanical engineering at Carnegie Mellon who uses specialized additive manufacturing techniques for research ranging from brain-computer interfaces to biomonitoring devices. "Because our technique can quantify the immune response to vaccination, it is very relevant in the current environment."

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Carnegie Mellon University