At-home medical testing using smartphone-powered microchip

There are already portable devices used for detecting diseases – rapid COVID-19 antigen test, for example – but scaling these down to a micro-level has always been difficult, due to so many moving parts.

However, a team of researchers at the University of Minnesota has created a microfluidic device that functions without all the bulky components such as pumps, tubing, and wires. Not only that, but it can be powered wirelessly by a smartphone, opening the door for faster and more affordable at-home medical testing.

“It’s not an exaggeration that a state-of-the-art, microfluidic lab-on-a-chip system is very labour intensive to put together,” said Sang-Hyun Oh, an electrical and computer engineering professor and senior author of the study. "Our thought was, can we just get rid of the cover material, wires and pumps altogether and make it simple?”

To give you some idea, many lap-on-chip systems work by moving liquid droplets across a microchip to detect the virus pathogens or bacteria inside the sample. This new method, however, was surprisingly inspired by wine – more specifically, the ‘legs’ or long droplets that form inside a wine bottle due to surface tension caused by evaporation of alcohol.

The technique involves placing tiny electrodes close together on a 2cm x 2cm chip, which generate strong electric fields that pull droplets across the chip and create a similar ‘leg’ of liquid to detect molecules within.

With only 10 nanometres between the electrodes, the electric field is so strong that the chip doesn’t need as much electricity to function. This meant the researchers could activate the chip using the same technology currently used for contactless payments – near-field communications from a smartphone. This is the first time a smartphone has been used to wirelessly activate narrow channels without microfluidic structures.

“This is a very exciting, new concept,” said Christopher Ertsgaard, lead author of the study and a recent University alumnus. “During this pandemic, I think everyone has realised the importance of at-home, rapid, point-of-care diagnostics. And there are technologies available, but we need faster and more sensitive techniques. With scaling and high-density manufacturing, we can bring these sophisticated technologies to at-home diagnostics at a more affordable cost.”

Start-up company GRIP Molecular Technologies is currently working with the team of researchers to commercialise this new device. “To be commercially successful, in-home diagnostics must be low-cost and easy-to-use,” said Bruce Batten, Founder and President of GRIP Molecular Technologies. “Low voltage fluid movement, such as what Professor Oh’s team has achieved, enables us to meet both of those requirements. GRIP has had the good fortune to collaborate with the University of Minnesota on the development of our technology platform. Linking basic and translational research is crucial to developing a pipeline of innovative, transformational products.”