Researchers have created a Smartphone-Powered Microchip for Medical Diagnostic Testing at Home

A research team from the University of Minnesota Twin Cities has created a new microfluidic chip for illness diagnosis that has a small number of components and can be charged wirelessly by a smartphone. The breakthrough paves the way for more convenient and economical at-home medical testing.

Nature Communications, a peer-reviewed, open-access scientific publication published by Nature Research, published the researchers’ study. Researchers are also striving to make the technology commercially viable.

Microfluidics is the study and manipulation of liquids at a microscopic level. Developing “lab-on-a-chip” technology, or the ability to make devices that can diagnose diseases from a very little biological sample, such as blood or urine, is one of the most popular applications in the field.

For example, scientists currently have portable instruments for identifying some illnesses, such as quick COVID-19 antigen tests. However, the necessity for so many moving parts is a major impediment to developing more complex diagnostic devices that might, for example, identify the exact strain of COVID-19 or assess biomarkers like glucose or cholesterol.

These chips would necessitate materials to encapsulate the liquid inside, pumps and tubing to manipulate the liquid, and wires to operate the pumps, all of which are challenging to scale down to the micro-level. Researchers at the University of Minnesota Twin Cities have developed a microfluidic device that does not require any of the bulky components.

“Researchers have been extremely successful when it comes to electronic device scaling, but the ability to handle liquid samples has not kept up,” said Sang-Hyun Oh, a professor in the University of Minnesota Twin Cities Department of Electrical and Computer Engineering and senior author of the study.

“It’s not an exaggeration that a state-of-the-art, microfluidic lab-on-a-chip system is very labor-intensive to put together. Our thought was, can we just get rid of the cover material, wires, and pumps altogether and make it simple?”

This is a very exciting, new concept. During this pandemic, I think everyone has realized 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.

Christopher Ertsgaard

Many lab-on-a-chip devices identify virus infections or bacteria inside a sample by moving liquid droplets across a microchip.

The method developed by University of Minnesota researchers was inspired by unusual real-world phenomena known to wine drinkers: “legs,” or lengthy droplets that form within a wine bottle due to surface tension generated by alcohol evaporation.

The researchers used a technology developed by Oh’s team in the early 2010s to position small electrodes very close together on a 2 cm by 2 cm chip, which generates strong electric fields that drag droplets across the chip and create a comparable “leg” of liquid to identify chemicals therein.

Because the electrodes are so close together (with only 10 nanometers between them), the generated electric field is so strong that the chip can run on less than a volt of power.

The researchers were able to activate the diagnostic chip using near-field communication signals from a smartphone, the same technology that is used for contactless payment in stores, due to the extremely low voltage required.

This is the first time that researchers have been able to utilize a smartphone to wirelessly activate narrow channels without the usage of microfluidic structures, paving the path for more affordable and accessible at-home diagnostic gadgets.

“This is a very exciting, new concept,” said Christopher Ertsgaard, lead author of the study and a recent CSE alumnus (ECE Ph.D. ’20). “During this pandemic, I think everyone has realized 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.”

To commercialize the microchip platform, Oh’s lab is collaborating with GRIP Molecular Technologies, a Minnesota firm that makes at-home diagnostic gadgets. The device is designed to identify viruses, pathogens, bacteria, and other biomarkers in liquid samples and has a wide range of applications.

“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.”

In addition to Oh and Ertsgaard, the research team included University of Minnesota Department of Electrical and Computer Engineering alumni Daniel Klemme (Ph.D. ’19) and Daehan Yoo (Ph.D. ’16) and Ph.D. student Peter Christenson.

The National Science Foundation provided funding for this study (NSF). Oh was awarded the Sanford P. Bordeau Endowed Chair and the McKnight University Professorship at the University of Minnesota.

The manufacture of the devices took place at the University of Minnesota’s Minnesota Nano Center, which is funded by the National Science Foundation through the National Nanotechnology Coordinated Infrastructure (NNCI).