How laser test helps detect COVID-19 from saliva in seconds
Innovative test is different from PCR and antibody test, and gives faster, accurate result
Highlights
- A new test using laser technology pioneered in Abu Dhabi speeds up mass screening for coronavirus.
- The new system is considered a "game-changer" and the new first line of defence against community viral transmission.
- The technique, known as Diffractive Phase Interferometry (DPI), looks for specific inflammation markers caused by a COVID-19 infection in a sample.
DUBAI / ABU DHABI: For years, researchers had been developing a laser-based reader to detect bacteria and even cancer.
Now, in Abu Dhabi, an ultra-sensitive light-based sensor had been “repurposed” to detect coronavirus in saliva or nasal swab.
The technique, known as Diffractive Phase Interferometry (DPI), looks for specific inflammation markers caused by COVID-19 infection in a sample.
SEE MORE
- Explained: COVID-19 test for entering Abu Dhabi
- Testing the waters: South Korea's waterparks open under new anti-COVID-19 measures
- Rapid COVID-19 screening test for Abu Dhabi – all you need to know
- Do I need a COVID-19 test before flying out of the UAE?
- Residents returning to Dubai: Who pays for COVID-19 test and treatment?
It is different from PCR (polymerase chain reaction) and antibody tests. Proponents of this new testing technology say it is highly accurate.
First line of defence
The laser-based border test is still not as definitive as the PCR nasal swab, but it’s considered advanced and reliable enough to help in a mass screening drive.
The PCR is highly accurate, but takes hours or days to process samples. DPI, on the other hand, gives results in minutes.
The gear was developed by Abu Dhabi-based QuantLase Imaging Lab, a medical arm of Abu Dhabi Securities Exchange-listed International Holding Co (IHC).
The are several DPI testing centres in Abu Dhabi now open, including the one in Ghantoot operated by Tamouh Healthcare.
The number goes up to 8,000 on weekends.
Officials expect up to 10,000 people to pass through the tent every day during the Eid break.
What happens if I test negative on DPI?
A negative test on the DPI machine means you will be allowed to enter Abu Dhabi within 48 hours from the time of testing, health authorities said.
What if my DPI test is positive?
If you test positive on the DPI machine, it means you would need a PCR test at the center, which then costs Dh320. The examinee must stay home until the result is out.
'Game-changer'
The UAE has pioneered the DPI-based rapid test. The non-invasive test uses “optical biosensors” and is seen as a game-changer in the coronavirus fight.
Using what is called "nanophotonic biosensors", based on a specialised complementary metal-oxide semiconductor (CMOS), it detects virus antigens using miniaturised chips — from saliva or a nasal swab.
The nanosensor can detect robinucleic acid (RNA) strands that identify SARS-CoV-2.
Specifically, the test detects changes in the cellular structure when infected by the virus, explained Dr. Pramod Kumar, who leads the research team.
Therefore, it detects COVID-19 in humans as soon as it is present in the body.
In May, the Abu Dhabi DPI team announced they had already created six DPI working laboratory demonstrator test devices.
This presents a number of advantages compared to traditional antibody test, which tend to kick up high rates of "false negatives". The latter is also more invasive as it uses a ‘finger-prick” kit to detect the presence of antibodies in a person.
DPI laser testing advantages:
- Is low-cost and delivers faster results, allowing for mass screening;
- Uses a non-invasive method (via saliva or nasal swab sample);
- It looks for specific viral markers and subjects them to light sensors, giving results within seconds;
- Detecs in real-time with high specificity from a low-concentration sample;
- More reliable than an antibody test;
- Modular, portable testing gear, can be used a point-of-care or bedside detector
- Needs minimal training to operate
Sample preparation
Once a sample is prepared and is in place, the device confirms a positive or negative for coronavirus instantaneously.
However, allowing for preparation time and analysis, a result — from sample to diagnosis — may take up to 30 minutes.
Interferometers are widely used in science and industry for the measurement of small displacements, refractive index changes and surface irregularities.
In most interferometers, light from a single source is split into two beams that travel in different optical paths. These beams are then re-combined to produce interference.
In analytical science, interferometers are used to measure lengths and the shape of optical components with nanometer precision; they are the highest precision length measuring instruments in existence.
Besides biomolecular interactions, interferometry is also being used in astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, spectroscopy (and its applications to chemistry), quantum mechanics, nuclear and particle physics, plasma physics, remote sensing, among others.
Testing
European scientists are also testing the same laser detector in the COVID-19 fight. For example, researchers in Spain have tested the demonstrators on patients’ samples provided by Vall D´Hebrón Hospital in Barcelona and several other hospitals in Spain.
The Spanish DPI testing gear is contained in portable box (25x15x25 cm), and controlled from a tablet. Its proponents from Catalan Institute of Nanoscience and Nanotechnology's said their rapid test kit is accurate, sensitive, non-invasive, inexpensive to produce and is user-friendly. Preparing of samples is the only technical expertise required, so the equipment could be widely deployed for general practitioners or nurses to test patients.
May: The Abu Dhabi DPI team announce they had already created six DPI working laboratory demonstrator test devices.
July 14, 2020: Abu Dhabi introduces the laser-based test technique to screen for COVID-19 prior to entry in the emirate.
July 18, 2020: Tamouh Healthcare opens second new tent for DPI screening in Seih Shoaib to triple the capacity at the first tent in Ghantoot area.
July 27, 2020: The Abu Dhabi Health Services (SEHA) adds three more test centers (Zayed Sports City, Corniche area, and Hili area in Al Ain) using DPI.
July 30, 2020: The DPI test pre-booking rule waived for families.
Medical innovations in the UAE
The United Arab Emirates is consolidating its position as a centre of innovation. It has pioneered health research and the fight against COVID-19.
For example, doctors at the Abu Dhabi Stem Cell Centre have devised a world-first nebuliser-based stem cell therapy which has proven to treat severe cases of coronavirus, and increase survival rates.
The UAE has also repurposed Strata's airctaft parts manufacturing facility in the desert oasis city of Al Ain to produce 90,000 N95 masks daily.
The UAE has so far airlifted medical gear to 71 countries, equivalent to 1,046 metric tons of aid. With the DPI laser test, the UAE has shown its ability to innovate to help solve a global health challenge.
It's not immediately clear whether the Abu Dhabi's DPI tester would be mass produced for export.