Researchers Create Lab-on-a-Chip for Quick Infection Testing

December 04, 2020 by Luke James

As the pandemic resurges in many parts of the world, researchers have found a way to bring the speed and accuracy of infection testing to mobile devices with a lab-on-a-chip.

A new lab-on-a-chip has been developed by researchers at Imperial College London who hope it can pave the way for low-cost portable diagnostic testing. 

The lab-on-a-chip (LoC) technology, known as TriSilix, is a "micro laboratory" that can reportedly perform a scaled-down version of the polymerase chain reaction (PCR) test on the spot, presenting its results in just a few minutes. PCR, which detects viruses and bacteria in biological samples, is usually performed in a laboratory, meaning that test results don’t become immediately available. 


The dimensions of TriSilix are 10 x 10 x 0.65 mm

The dimensions of TriSilix are 10 x 10 x 0.65 mm. Image used courtesy of Imperial College London

Each LoC device contains a DNA sensor, temperature detector, and heater so that the testing process can be automated. According to the researchers' published findings in Nature Communications, a standard smartphone battery is capable of powering up to 35 tests on a single charge.


Silicon-Based Micro-qPCR

The researchers say that they’ve developed a series of methods for producing LoC devices in a standard laboratory rather than large cleanroom facilities typically required to make electronic chips.

They also say that they were able to produce the chips, which are made entirely from silicon, while cutting down the cost and time it takes to fabricate them, enabling them to, in theory, be produced anywhere in the world.


The Micro-qPCR lab-on-a-chip

The Micro-qPCR lab-on-a-chip produced by researchers in London. It’s cheap to make, easy to fabricate, and can provide results in a matter of minutes, according to researchers. Image used courtesy of Imperial College London


The project’s lead researcher, Dr. Firat Guder, said: “Rather than sending swabs to the lab or going to a clinic, the lab could come to you on a fingernail-sized chip. You would use the test much like how people with diabetes use blood sugar tests, by providing a sample and waiting for results—except this time it’s for infectious diseases.” 


Fabricating the TriSilix Chips

To create an ultra-low-cost LoC device, the architecture exploits the properties of silicon and integrates three modes of operation: an electrical heater, a thermistor, and a label-free electrochemical sensor. 


A schematic illustration of the fabrication of a TriSilix chip and wafer-scale fabrication of TriSilix chips

A schematic illustration of the fabrication of a TriSilix chip and wafer-scale fabrication of TriSilix chips. Image used courtesy of Nature Communications


To achieve cleanroom-free fabrication, the researchers developed a series of fabrication methodologies based on wet etching to form porous silicon, electroplating, thermal bonding, and laser cutting. In this study, fabrication began with lightly doped p-type 4-inch silicon wafers, but the researchers point out that larger wafers would also work. 


Diagnosing the Cold, Flu, and Possibly COVID-19 From Home

The researchers have already used TriSilix to diagnose bacterial infections that are usually found in animals. Even more exciting, however, is that they've also been able to identify a synthetic version of the genetic material from the virus behind COVID-19, SARS-CoV-2. 

The researchers hope that the system can soon be mounted onto a handheld blood sugar test-style device, enabling people to test themselves and receive results at home for ailments like the common cold, flu, and urinary tract infections. 


TriSilix architecture

The TriSilix device's transducer integrates three modes: a electrochemical nucleic acid sensor, a heater, and a temperature sensor. Screenshot used courtesy of the Guder Research Group

Due to its high portability, the TriSilix device could in theory accelerate the diagnosis of infections and reduce costs by eliminating the need for transport and lab-based testing. And because the tests can be self-administered without the need for a medical professional, those who test positive for an infection like COVID-19 could immediately isolate themselves to minimize the transmission risk. 

The researchers plan to validate their TriSilix LoC devices with clinical samples and are currently looking for partners to begin delivering testing in resource-limited settings.


Electronics and COVID-19 Diagnostics

The researchers at Imperial College London aren't the only ones who have their eyes on chip-level technology to broaden pathogen testing. In the past year, many other research teams and companies have also invested resources in finding silicon solutions. Here are a few you might have missed: