Point of Care

New Low-Cost Sensor Offers Promising Test for Rapid, At Home COVID-19 Testing

Laboratory companies and scientists are working furiously to produce the rapid, point of care testing technology needed to prevent asymptomatic people from spreading SARS-CoV-2. And in a promising new development, researchers from the California Institute for Technology (Caltech) have developed a new type of test that combines multiple kinds of data with a low-cost sensor that could enable rapid in-home diagnosis of a COVID infection in less than 10 minutes. In addition, the multiplexed test uses small volumes of saliva or blood and can be utilized without the involvement of a health care professional.

The Diagnostic Challenge

To contain the spread of COVID-19, it is vital to ensure that people with SARS-CoV-2 stay home. The problem is that those who are infected are often asymptomatic and have no idea that they are exposing others to the virus. While asymptomatic people can always get tested, scarce testing resources are needed to diagnose patients who do exhibit symptoms. Moreover, current COVID-testing technologies generally take hours or days to produce results and require the use of expensive, complex equipment.

Truly effective screening of the asymptomatic would require tests capable of rapidly and accurately identifying infections that people could easily self-administer, like a scanning device that could be used before leaving home to ensure that the COVID-19 coast is clear.

The New Sensor-Based Test

Maybe, just maybe, the new Caltech test will turn out to be the prototype for this solution. A team of scientists that has previously developed wireless sensors capable of monitoring conditions such as gout and stress levels via the detection of extremely low levels of specific compounds in blood, saliva, or sweat, carried out the research in the laboratory of Wei Gao, assistant professor in the Andrew and Peggy Cherng Department of Medical Engineering at Caltech.

Gao’s sensors are made of graphene, a sheet-like form of carbon. A plastic sheet etched with a laser generates a 3D graphene structure with tiny pores. Those pores create a large amount of surface area on the sensor, which makes it sensitive enough to detect, with high accuracy, compounds that are only present in very small amounts. The new version of the sensor, which is called the SARS-CoV-2 RapidPlex, contains antibodies and proteins that allow it to detect the presence of the virus itself; antibodies created by the body to fight the virus; and chemical markers of inflammation, which indicate the severity of the COVID-19 infection.

The device has been tested only in the laboratory thus far with a small number of blood and saliva samples obtained from individuals who have tested positive or negative for COVID-19. While preliminary results indicate that the sensor is highly accurate, the developers caution that larger-scale tests must still be performed.


Although exciting, the new scanner test will take at least a year to roll off the pipeline. With the pilot study completed, the next step will be to test how long the sensors last with regular use, and then begin testing them with hospitalized COVID-19 patients. After the in-hospital testing is completed, the researchers will have to evaluate the suitability of the tests for in-home use. Of course, once all of the testing is completed, the device will have to receive regulatory approval from the U.S. Food and Drug Administration before it is available for widespread use at home. The developers hope to be able to begin testing for in-home use sometime next year. 


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