May 3 2022Reviewed by Alex Smith
A research team from the University of Minnesota Twin Cities has created a novel microfluidic chip for disease diagnosis, which 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 journal published by Nature Research, has published the 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 capacity to make devices that can detect diseases from a very little biological sample, such as blood or urine, is one of the most prominent applications in the area.
Some diseases can already be diagnosed using portable instruments, such as fast COVID-19 antigen testing. However, the necessity for so many moving parts is a major impediment to developing more complex diagnostic chips that might, for example, identify the particular strain of COVID-19 or assess biomarkers like glucose or cholesterol.
These chips would require materials to encapsulate the liquid within, pumps and tubing to control the liquid, and wires to operate the pumps — all of which are challenging to scale down to the micro size. Researchers at the University of Minnesota Twin Cities have developed a microfluidic device that does not require any 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. 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?
Sang-Hyun Oh, Study Senior Author and Professor, Department of Electrical & Computer Engineering, University of Minnesota Twin Cities
Many lab-on-a-chip techniques identify virus pathogens or bacteria inside a sample by moving liquid droplets over a microchip. The method developed by the University of Minnesota researchers was inspired by a unique real-world occurrence that wine drinkers will be aware of: the “legs,” or lengthy droplets that form within a wine bottle owing to surface tension induced by alcohol evaporation.
The researchers used a technology developed by Oh’s team in the early 2010s to position small electrodes extremely close together on a 2 cm by 2 cm chip, which generates strong electric fields that drag droplets across the device and form a comparable “leg” of liquid to identify the molecules inside.
As the electrodes are so close together (with only 10 nm separating them), the generated electric field is so intense that the chip can run on less than a volt of power. The researchers were capable of activating the diagnostic chip utilizing near-field communication signals from a smartphone, the very same technology that is used for contactless payment in shops, due to the extremely low voltage required.
This is the first time that researchers have been able to utilize a smartphone to remotely activate narrow channels without the use of microfluidic structures, paving the path for more affordable and accessible at-home diagnostic devices.
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, PhD, Study Lead Author, Department of Electrical & Computer Engineering, University of Minnesota
Ertsgaard is a recent CSE alumni (ECE PhD ‘20).
To commercialize the microchip platform, Oh’s lab is collaborating with GRIP Molecular Technologies, a Minnesota firm that makes at-home diagnostic devices. The chip is designed to identify pathogens, viruses, 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. 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.
Bruce Batten, Founder and President, GRIP Molecular Technologies
In addition to Oh and Ertsgaard, the research team comprised Daniel Klemme (Ph.D. ‘19) and Daehan Yoo (Ph.D. ‘16) of the University of Minnesota Department of Electrical and Computer Engineering, as well as Ph.D. student Peter Christenson.
The National Science Foundation (NSF) provided funding for this study. 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 under the National Nanotechnology Coordinated Infrastructure (NNCI).
Ertsgaard, C. T., et al. (2022) Open-channel microfluidics via resonant wireless power transfer. Nature Communications. doi.org/10.1038/s41467-022-29405-2.