Novel Mouthguard Monitors Health Markers

A new mouthguard can monitor uric acid in the saliva and transmit the information wirelessly to a smart phone, laptop, or tablet.

Developed at the University of California, San Diego (UCSD; USA), the mouthguard monitor uses printed sensor technology based on silver, Prussian blue ink and uricase, an enzyme that reacts specifically with uric acid. Because human saliva is an extremely complex viscous liquid that contains many different biomarkers, the researchers set up the chemical equivalent of a two-step authentication system to make sure that the sensors only reacted with the uric acid. Similar sensors are also being developed for lactate and cortisol.

The first step is a series of chemical keyholes, which ensures that only the smallest biochemicals get inside the sensor. The second step is a layer of uricase trapped in polymers, which reacts selectively with uric acid. The reaction between acid and enzyme generates hydrogen peroxide (H2O2), which is detected by the Prussian blue ink. That information is then transmitted to an electronic board which that senses the output of the sensors, digitizes the output, and then wirelessly transmits data to a smart phone, tablet or laptop.

The researchers conducted a study using saliva samples from healthy volunteers and spread them on the sensor, which produced readings in a normal range. Next, they collected saliva from a patient who suffers from hyperuricemia, a condition characterized by an excess of uric acid in the blood; the sensor detected more than four times as much uric acid in the patient's saliva than in the healthy volunteers. When the patient took Allopurinol, they were able to document a drop in uric acid levels over four or five days as the medication took effect. The study was published in the September 2015 issue of Biosensors and Bioelectronics.

“The ability to monitor continuously and noninvasively saliva biomarkers holds considerable promise for many biomedical and fitness applications,” said lead author Professor of nano-engineering Joseph Wang, PhD, of the Center for Wearable Sensors at UCSD. “It could be used in the future to monitor hospitalized patients continuously without the need for invasive procedures, monitor athletes' performance, or study stress levels in soldiers and pilots.”

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University of California, San Diego