Monday, May 23, 2022


A device made with nanodiamonds, much smaller than specks of dust, would function as a laser pointer and detect the coronavirus with an efficiency far above the usual tests and instantly

This is a very novel approach to testing for the presence of the virus that causes Covid-19. Enables faster, less expensive and potentially less prone to erroneous tests than existing screening methods

In an interview with the Spanish expert in quantum computers, Ignacio Cirac, he explained a basic question of quantum physics: “We still do not fully understand particles on a quantum scale , but that does not mean that we cannot use their properties. You don’t have to understand it, you have to live with it and use it.

Without fully understanding the disturbing behavior of particles on the smallest scale, we use their properties when we use GPS, and when we go to the doctor for an MRI we do it thanks to quantum physics. Now, MIT physicists propose the development of a device based on quantum physics that would detect the virus with a much smaller margin of error than conventional tests, with much higher efficiency and at a reduced cost, despite the fact that for its development you need diamond particles. This device is one of the diamond-based quantum sensor proposals to build powerful tools for biomedical diagnostics.

Although the work, developed at MIT and based on quantum effects, is still theoretical, these detectors could potentially be adapted to detect virtually any virus, according to the researchers.

The new approach is described in an article  published Thursday in Nano Letters magazine   by Changhao Li, an MIT doctoral student; Paola Cappellaro, professor of nuclear science and engineering and physics; and Rouholla Soleyman and Mohammad Kohandel of the University of Waterloo.


Existing tests for the SARS-CoV-2 virus include rapid tests that detect specific viral proteins and polymerase chain reaction (PCR) tests that take several hours to process. Neither of these tests can quantify the amount of virus present with great precision. Even standard PCR tests can have false negative rates of more than 25 percent.

In contrast, the new test could have false negative rates below 1 percent and be sensitive enough to detect just a few hundred strands of viral RNA, in just one second.


The MIT researchers start from diamond nanoparticles. In these particles, much smaller than specks of dust, they are part of a crystalline lattice that shapes the diamond. This network, we insist that its scale is nanometric, has defects, voids, which are called nitrogen vacancies (NV). These voids are extremely sensitive to minimal disturbances, so minimal that we are talking about quantum effects. The crystal lattice of diamond is being explored for a wide variety of detection devices that require high sensitivity.

The new method would involve coating the nanodiamonds containing these NV centers with a material that is magnetically coupled to them and has been treated to bind only with the virus-specific RNA sequence. When virus RNA is present and binds to this material, it breaks the magnetic connection and causes changes in diamond fluorescence that are easily detected with a laser-based optical sensor.

The sensor uses only inexpensive materials (the diamonds involved are smaller than specks of dust), and the devices could be scaled up to analyze an entire batch of samples at once, the researchers explain.

The lasers used to read the results are comparable to cheap and widely available commercial green laser pointers

The gadolinium-based coating with its RNA-tuned organic molecules can be produced using common chemical processes and materials, and the lasers used to read the results are comparable to cheap and widely available commercial green laser pointers.

While this initial work was based on detailed mathematical simulations that showed that the system can work in principle, the team continues to work to translate that into a functional, lab-scale device to confirm the predictions.

“We don’t know how long it will take to make the final demonstration,” says Li. His plan is to do a basic lab pre-test first and then work on ways to optimize the system to work in real virus diagnostic applications.

The multidisciplinary process requires a combination of expertise in physics and quantum engineering, to produce the detectors themselves, and in chemistry and biology, to develop the molecules that bind with viral RNA and find ways to bind them to the surfaces of diamonds.

Even if complications arise from translating the theoretical analysis into a working device, says Cappellaro, there is such a large margin of lower false negatives that is predicted from this work that it will likely still have a huge advantage over standard PCR tests in that sense. And even if the precision were the same, this method would still have a huge advantage in producing your results in a matter of minutes, rather than taking several hours.

The basic method can be tailored to any virus, including new ones that may emerge, simply by tailoring the compounds that are attached to the nanodiamond sensors to match the generic material of the specific target virus.



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