The GlucoScreen system, developed by researchers at the University of Washington in Seattle, uses the capacitive touch sensing capabilities of smartphones to measure blood glucose levels without the need for a separate reader.
According to the US Centres for Disease Control, one in three adults in the US has prediabetes, a condition marked by elevated blood sugar levels that could lead to the development of Type 2 diabetes.
If detected early, prediabetes can be reversed through lifestyle changes, such as improved diet and exercise. Eight out of 10 Americans with prediabetes do not know they have it however, putting them at increased risk of developing diabetes as well as disease complications that include heart disease, kidney failure and vision loss.
Current screening methods typically involve a visit to a healthcare facility for laboratory testing, or the use of a portable glucometer for at-home testing, meaning access and cost can be barriers to more widespread screening.
“In conventional screening a person applies a drop of blood to a test strip, where the blood reacts chemically with the enzymes on the strip. A glucometer is used to analyse that reaction and deliver a blood glucose reading,” said Anandghan Waghmare, lead author of a paper describing the work.
“We took the same test strip and added inexpensive circuitry that communicates data generated by that reaction to any smartphone through simulated tapping on the screen. GlucoScreen then processes the data and displays the result right on the phone, alerting the person if they are at risk so they know to follow up with their physician.”
This approach could make glucose testing less costly and more accessible, the researchers said, particularly for one-time screening of a large population.
The GlucoScreen test strip works by sampling the amplitude of the electrochemical reaction that occurs when a blood sample mixes with enzymes five times each second.
The strip then transmits the amplitude data to the phone through a series of touches at variable speeds. The greater the time between taps, the higher the amplitude associated with the electrochemical reaction on the strip.
“Instead of a single tap to produce a single action, it’s doing multiple taps at varying speeds. It's comparable to how Morse code transmits information through tapping patterns,” said Waghmare.
The technique does not require complicated electronic components, the researchers said, so it minimises the cost of manufacturing and the power required for it to operate – provided via photodiodes drawing power from the phone’s flash.
The flash is automatically engaged by the GlucoScreen app, which walks the user through each step of the testing process. First, a user fixes each end of the test strip to the front and back of the phone. Next, they prick their finger and apply a drop of blood to the biosensor attached to the test strip. After the data is transmitted from the strip to the phone, the app reportedly uses machine learning to analyse the data and calculate a blood glucose reading.
The researchers' results suggested that GlucoScreen's accuracy is comparable to a standard glucometer testing. The team found the system to be accurate at the crucial threshold between a normal blood glucose level, at or below 99 mg/dL (5.5mmol/L), and prediabetes, defined as a blood glucose level between 100 and 125 mg/dL (5.6-6.9mmol/L).
“Because we use the built-in capacitive touch screen that's present in every smartphone, our solution can be easily adapted for widespread use,” said co-author Jason Hoffman. “We’ve designed it to be ‘plug and play’… you don’t need to do anything with the phone, other than install the app. Whatever model you have, it will work off the shelf.”
The system is currently a research prototype. User-focused and clinical studies, along with alterations to how test strips are manufactured and packaged, would be required before the system could be made widely available, the team said.
The work was published in Proceedings of the Association for Computing Machinery on Interactive, Mobile, Wearable and Ubiquitous Technologies.
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