Researchers from Caltech, Peking University in China, Santa Clara University, and University of California, Los Angeles have developed a new wearable sensor that can detect gout-causing compounds in sweat. The device relies on novel laser-engraved chemical sensors to detect gout-causing compounds uric acid and tyrosine at concentrations much lower than previously possible. Moreover, the same device also measures sweat rate, body temperature, and heart and respiration rates. The technology may be an important development for the field of wearable sensors and for the tens of millions of people worldwide who suffer from or are at risk of gout.
Currently, sweat sensors do not exist for uric acid and tyrosine, which are key metabolites that are risk factors for cardiovascular disease, type 2 diabetes, and liver diseases, and are used clinically for management of gout. Currently, these metabolites are measured via blood draw, which can be painful, so only capture a single time-point of metabolite levels. To address these limitations, the researchers developed a sweat sensor to detect uric acid and tyrosine to allow for painless and dynamic monitoring of metabolite concentrations.
The device is made of microfluidic channels which lead to physical and chemical sensors. In order to improve manufacturability, the researchers created the microfluidic channels within plastic using a low-cost CO2 laser engraving method. The metabolites are measured using a laser-engraved graphene chemical sensor, a graphene-based physical sensor, and a multi-inlet microfluidic module for dynamic sweat sampling. The chemical sensor actively measures uric acid and tyrosine concentrations, while the physical sensor measures skin temperature, heart rate, and respiration rate. The device can wirelessly transmit data via Bluetooth for analysis and visualization.
In key experiments, the team tested the device in subjects under exercise and after a protein-rich diet. Additionally, the researchers used the device for gout monitoring in patients and healthy controls after a purine-rich meal challenge, which boosts uric acid levels. They found that uric acid levels in sweat were higher in patients with gout than healthy individuals, a trend which was observed with the gold standard blood draw method.
“Such wearable sweat sensors have the potential to rapidly, continuously, and noninvasively capture changes in health at molecular levels,” said Wei Gao, assistant professor of medical engineering at Caltech, in a press release. “They could enable personalized monitoring, early diagnosis, and timely intervention. Considering that abnormal circulating nutrients and metabolites are related to a number of health conditions, the information collected from such wearable sensors will be invaluable for both research and medical treatment.”
The publication in Nature Biotechnology: A laser-engraved wearable sensor for sensitive detection of uric acid and tyrosine in sweat