Smartphone-powered microchip developed for home medical diagnostic testing

A research team from the University of Minnesota Twin Cities has developed a new microfluidic chip for disease diagnosis that uses a minimal number of components and can be powered wirelessly by a smartphone. Innovation opens the door to faster and more affordable home medical tests.

The researchers’ article is published in Nature Communication, a peer-reviewed, open-access scientific journal published by Nature Research. Researchers are also working to commercialize the technology.

Microfluidics involves the study and manipulation of liquids on a very small scale. One of the most popular applications in the field is the development of “lab-on-a-chip” technology, or the ability to create devices capable of diagnosing diseases from a very small biological sample, blood or urine, for example.

Scientists already have portable devices to diagnose certain conditions, for example rapid COVID-19 antigen tests. However, a major obstacle to designing more sophisticated diagnostic chips that could, for example, identify the specific strain of COVID-19 or measure biomarkers like glucose or cholesterol, is the fact that they need so many moving parts.

Chips like these would require materials to seal the liquid inside, pumps and tubing to manipulate the liquid, and wires to activate those pumps – all materials that are difficult to reduce to the micro level. Researchers at the University of Minnesota Twin Cities have been able to create a microfluidic device that works without all those bulky components.

“Researchers have had great success in scaling electronic devices, but the ability to manipulate liquid samples has not kept pace,” said Sang-Hyun Oh, a professor in the Department of Electrical Engineering. and Twin Cities Computing from the University of Minnesota and senior author of the study. “It’s no exaggeration to say that a state-of-the-art microfluidic lab system on a chip is labor intensive to assemble. Our thought was, can we just get rid of the roofing material, wires and pumps and simplify things? »

Many lab-on-a-chip technologies work by moving liquid droplets across a microchip to detect viral pathogens or bacteria inside the sample. The University of Minnesota researchers’ solution was inspired by a particular real-world phenomenon that wine drinkers will be familiar with: “legs,” or long droplets that form inside a bottle of wine. due to surface tension caused by the evaporation of alcohol.

Using a technique developed by Oh’s lab in the early 2010s, researchers placed tiny electrodes very close together on a 2cm by 2cm chip, which generate powerful electric fields that pull the droplets through the chip and create a “leg” of liquid similar to sensing molecules inside.

Because the electrodes are placed so close together (with only 10 nanometers of space between them), the resulting electric field is so strong that the chip only needs less than a volt of electricity to operate. . This incredibly low voltage requirement allowed the researchers to activate the diagnostic chip using near-field communication signals from a smartphone, the same technology used for contactless payment in stores.

This is the first time that researchers have been able to use a smartphone to wirelessly activate narrow channels without microfluidic structures, paving the way for cheaper and more accessible home diagnostic devices.

“This is a very exciting new concept,” said Christopher Ertsgaard, lead author of the study and recent CSE alumnus (ECE Ph.D. ’20). “During this pandemic, I think everyone has realized the importance of rapid home and point-of-care diagnostics. And there are technologies available, but we need faster and more sensitive techniques. at scale and high-density manufacturing, we can bring these sophisticated technologies to home diagnostics at a more affordable cost.

Oh’s lab is working with Minnesota startup GRIP Molecular Technologies, which makes home diagnostic devices, to commercialize the microchip platform. The chip is designed to have wide applications for the detection of viruses, pathogens, bacteria and other biomarkers in liquid samples.

“To be commercially successful, home diagnostics must be inexpensive and easy to use,” said Bruce Batten, Founder and President of GRIP Molecular Technologies. “Low-voltage fluid movement, like what Professor Oh’s team realized, allows us to meet both of these requirements. GRIP had the chance to collaborate with the University of Minnesota on the development of our technological platform. Linking basic and translational research is crucial to developing a pipeline of innovative and transformational products.

Reference: Ertsgaard CT, Yoo D, Christenson PR, Klemme DJ, Oh SH. Open channel microfluidics via resonant wireless power transfer. Nat Common. 2022;13(1):1869. doi: 10.1038/s41467-022-29405-2

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