A low-cost, non-invasive device uses light and saliva to quickly test Covid-19 patients

A team of researchers at ICFO and IrsiCaixa report on the development of a low-cost, portable, non-invasive device that uses light and saliva to test Covid-19 patients in less than 30 minutes. The results show that the device can detect very low concentrations of SARS-CoV-2 with 91.2% sensitivity and 90% specificity. This is similar to PCR, but antigen test.

The Covid-19 breakout became a game changer in the medical field in 2020. Research has blossomed and has begun to move in earnest to find solutions in a variety of ways. On the one hand, we are looking for vaccination to control the spread of the disease, and on the other hand, we are looking for testing techniques that may be available and accessible to everyone in the world. Initially, PCR was one of the few available technologies that could provide accurate results, but this technology was expensive and required specialized personnel and equipment to perform them. Due to the growing demand for testing, antigen testing has become a much faster and cheaper alternative because it is less sensitive than before, but it is less reliable.

In a recent study published in Biomedical Optics Express, ICFO researchers Rubaiya Hussain, Alfredo E. Ongaro, Ewelina Wajs, ICREA Professor Valerio Pruneri, researchers Maria L. Rodriguez DeLa Concepción, Eva Riveira-Muñoz, Ester Ballana, Julià Blanco, Ruth Toledo, Anna Chamor A new technology that can provide fast and reliable detection of SARS-CoV-2 in saliva samples of COVID-19, led by Masanella, Lourdes Mateu, Eulalia Grau, Bonaventura Crotet and Jorge Carrillo of the IrsiCaixa AIDS Research Institute. Demonstration and developed tests. The team achieved a detection limit much lower than the antigen test, and blinded more than 50 patients with results with 91.2% sensitivity and 90% specificity.

Things necessary

IrsiCaixa researchers Marisa Rodriguez and Jorge Carrillo collaborate daily with COVID-19 patients, saying, “In the early stages of a pandemic, it is very possible to detect all infected individuals to control the spread of the virus. It turned out to be important, so IrsiCaixa gathered with researchers to take the initiative, Bonaventura Crotet, to combine the benefits of each and to infect SARS-CoV-2 from saliva. We have found the need to find alternatives to PCR and antigen testing to detect the virus. For most patients, samples are available because they are much easier and less invasive. ”With this idea in mind, they Contacted the ICFO for technology for an optical-based imaging and diagnostic device developed by Valerio Pruneri’s team. ICFO researcher Alfredo Ongaro vividly recalls: Sampling and achieving accurate results on a short time scale, perhaps as fast as an antigen test. “

Flow virus meter

The team has developed a flow virus meter, a device that uses light to detect the concentration of viruses in a liquid flowing through a very small tube called a microfluidic channel.

This device uses a few drops of saliva and fluorescent markers. When collecting saliva from the saliva of the patient’s mouth, it is introduced by putting it in a solution containing a fluorescent antibody. If saliva contains virus particles, fluorescent antibodies will attach to the virus.

Rubaiya Hussain, ICFO researcher

Then, “The reader collects the sample and sends it to the microfluidic channel. The microfluidic channel goes through the laser illumination detection setup. The laser illuminates the sample and if virus particles are present, the fluorescence is unique. Emits an enhancement of the signal. Within 1 minute, the reading is converted to the peak of the graph, warning the system that the sample is positive. “

The ICFO team conducted a blind test using 54 samples provided by IrsiCaixa, identifying 31 of the 34 positives and only 3 false negatives. In addition, they measured 3834 virus copies per milliliter. This means that the device can detect the presence of the virus at very low concentration levels, at least three orders of magnitude lower than the rapid antigen test on the market.

A device that anyone can use anywhere

Finally, ICFO researcher Ewelina Wajs points out: With very fast response times for culture-dependent gold standards, such as Legionella and E-coli. “

Researchers say they can run up to 2000 tests per day on a single device. The components that make up the device are commercially available at low cost and can be manufactured on a large scale. In addition, this technique also means reducing the need for plastic packaging for extensive testing on a single device. This is in favor of the Green Environment Policy.

Finally, its low cost and simple operational design could be an excellent solution for diagnosis and dissemination management in low-income countries where access to healthcare and vaccines for all populations is restricted. .. The fact that it does not need to be operated by professional staff or in a professional lab means that it is used for mass screening of the population in crowded areas such as restaurants, schools, offices, theaters and cinemas. ..