Researchers at the University of Michigan in Ann Arbor have invented a COVID-19 antibody test that’s portable, offers results quickly, and is inexpensive and precise. The microfluidic device was developed by Optofluidic Bioassay, a U-M startup.
The microfluidic device, or “lab on a chip,” shrinks multiple lab functions onto a chip that’s millimeters or centimeters in size.
The new system is believed to be the first microfluidic approach to a gold standard testing protocol known as enzyme-linked immunosorbent assay (ELISA). U-M researchers have previously published results showing their device can work as well as the slower, larger, standard ELISA setup.
U-M officials are validating the system for use on COVID-19 antibodies and have demonstrated they can detect synthetic COVID-19 antibodies. They are working with researchers at a hospital in New Jersey on experiments with blood from COVID-19 patients.
Labs around the U.S. are working to develop better antibody tests. The U-M approach is different because it centers on a device rather than chemical mixtures, or reagents, to detect COVID-19 markers.
“We are unique because we are a hardware company,” says Xudong (Sherman) Fan, a biomedical engineering professor at U-M and co-founder of Optofluidic Bioassay. “Anyone working on COVID-19 antibody tests can use their reagents in our device.”
Antibody tests can reveal who was already exposed to the virus and developed immunity, at least temporarily, and can go back to work safely. If widespread testing is completed, it could show the true scale of the pandemic and its death rate.
The researchers say their approach could give doctors near-real-time insights into how patients are responding to treatment or a vaccine once one is developed.
Small-scale antibody testing has been done in some countries. Kits are beginning to become available in the U.S., but they aren’t widely available yet.
Antibody, or serology tests are different from the tests being used to diagnose COVID-19. Instead of screening for the virus, it detects antibodies, or proteins the immune system manufactures to fight it.
The majority of labs working on serology kits are making a particular type called rapid diagnosis tests that give yes or no readings. False negatives can be a problem and, because they don’t give a lot of information, they aren’t useful in monitoring the immune system’s response during treatment.
A handful of labs are making ELISA tests. They are typically quantitative and accurate, showing the concentration of antibodies, which makes them more reliable and less prone to false positives. However, standard ELISA results take several hours, and the machines that provide the results are the size of refrigerators. The samples also need to be sent to the test lab for analysis.
Microfluidic ELISA, which is what the U-M researchers are working on, can give quantitative and accurate results in 15 minutes with blood from a finger prick. It is also portable.
“Our approach offers the best of both worlds,” Fan says. “We can achieve the quickness and simplicity of the rapid diagnostic test with the accuracy of the standard ELISA quantitative measure. Because our device generates such sensitive and quantitative measurements, we believe its use goes beyond identifying recovered patients. Antibodies begin to show up a few days after infection, so we could use this approach to monitor patients’ immune response to infection, treatment, and vaccination.”
The test machine can be the size of a microwave and can test multiple samples at once. It was invented at U-M several years ago and developed by Optofluidic Bioassay, which was founded by Fan and Maung (Malcolm) Khaing Oo, former research investigator of biomedical engineering and chief technology officer of Optofluidic.
“The estimated cost of testing is a few dollars per test of two to three different antibodies, making this a very viable option for use in hospitals, doctors’ offices, field clinics, and potentially even pharmacies,” says Xiaotian Tan, a doctoral student in biomedical engineering who is working on COVID-19 antibody testing with Fan.
The researchers plan to eventually apply for U.S. Food and Drug Administration Emergency Use Authorization.