A ‘micro laboratory’ chip, known as TriSilix, was recently developed at Imperial College London. It performs a miniature version of the polymerase chain reaction or PCR analysis on the spot. PCR is the gold-standard test for detecting viruses and bacteria in biological samples such as bodily fluids, feces, or environmental samples.

PCR is usually performed in a laboratory, which means test results aren’t immediately available. However, TriSilix can process and present results in a matter of minutes.

The chip is made from silicon. Silicon itself is cheap, however, it is typically expensive to process into chips. To make this new lab-on-a-chip, the researchers developed a series of methods to produce the chips in a standard laboratory, cutting the costs and time it takes to fabricate them and potentially allowing them to be produced anywhere in the world.

Rather than sending swabs to the lab or going to a clinic, TriSilix lets the lab could come to you on a fingernail-sized chip. Consumers with infectious diseases can use the test much like people with diabetes use blood sugar tests, simply providing a sample and waiting for results.

The researchers have so far used TriSilix to diagnose a bacterial infection mainly present in animals as well as a synthetic version of the genetic material from SARS-CoV-2, the virus behind COVID-19.

The researchers say the system could in the future be mounted onto handheld blood sugar test-style devices. This would let people test themselves and receive results at home for colds, flu, and recurrent infections.

Table-top devices for testing of infections like COVID-19 already exist, but these tests can be time-consuming and costly since the patient must go to a clinic, have a sample taken by a healthcare worker and go home or stay in the clinic to wait.  People leaving their homes when not feeling well increases the risk of spreading a pathogen to others.

If validated on human samples, this new test could provide results outside a clinic, at home, or on-the-go within minutes.

Furthermore, a highly portable test could accelerate the diagnosis of infections and reduce costs by eliminating the transportation of samples.  Such tests could be performed by citizens in the absence of highly trained medical professionals; hence, if they need to self-isolate, they can start immediately without potentially infecting others.

Making testing more accessible and cheaper is especially important for people in rural areas of low-income countries, where clinics can be far away and expensive to travel to.  If made available to patients, it could also be used to diagnose and monitor infections like urinary tract infections, which often recur despite antibiotics.

Monitoring infections at home could even help patients, with the help of their doctor, to personalize and tailor their antibiotic use to help reduce the growing problem of antibiotic resistance.

Each TriSilix lab-on-a-chip contains a DNA sensor, temperature detector, and heater to automate the testing process. A typical smartphone battery could power up to 35 tests on a single charge.

Next, the researchers plan to validate TriSilix with clinical samples, automate the preparation of samples and advance their handheld electronics. They are looking for partners and funders to help accelerate the translation of the technology to deliver testing at resource-limited settings at homes, farms, or remote locations in the developing world. 

Nature Communications, December 2020, “Disposable Silicon-Based All-in-one micro-qPCR for Rapid On-site Detection of Pathogens,” by Estefania Nunez-Bajo, et al.  © 2020 Springer Nature Limited.  All rights reserved.