A group of engineers at the University of California San Diego have developed a new soft and stretchy wearable skin patch that can monitor a person’s blood pressure (BP), heart rate (HR), glucose, and lactate, alcohol or caffeine levels at the same time.
This soft, stretchy patch can monitor the wearer’s blood pressure and biochemical levels at the same time. Image credit: UCSD
The patch – worn on the neck for best results – was tested on a number of subjects performing different tasks, such as exercising, consuming a high-sugar meal, and drinking a caffeinated or alcoholic beverage. The readings were almost as accurate as those from commercial monitoring devices.
Results were published on 15 February in the journal Nature Biomedical Engineering.
Having such a device available on the market could benefit countless patients whose medical conditions require simultaneous and continuous tracking of multiple health indicators, such as people with heart disease and diabetes, or patients in intensive care units.
Engineers are getting ever closer to developing an all-in-one health monitoring skin patch that would replace some of the most expensive medical equipment. Image: Sempionatto, J.R., Lin, M., Yin, L. et al. An epidermal patch for the simultaneous monitoring of haemodynamic and metabolic biomarkers. Nat Biomed Eng (2021).
“The novelty here is that we take completely different sensors and merge them together on a single small platform as small as a stamp,” said co-author Joseph Wang. “We can collect so much information with this one wearable and do so in a non-invasive way, without causing discomfort or interruptions to daily activity.”
The patch is a thin sheet of stretchy polymers with a BP sensor and two chemical sensors – one for lactate (a biomarker of physical exertion), caffeine and alcohol in sweat, and one that measures glucose levels.
Blood pressure is monitored by a sensor welded to the patch by a conductive ink. Measurements are performed by applying a voltage to the transducers, which send ultrasound waves that bounce off the closest artery and return an echo signal translated into a BP reading.
The lactate, caffeine and alcohol sensor, printed on the patch from conductive ink, works by releasing a drug called pilocarpine into the skin and detecting the chemical substances present in the sweat induced by the drug.
And lastly, the glucose sensor, likewise printed on the patch from conductive ink, is an electrode that delivers mild electric shocks to the skin, thereby stimulating the release of interstitial fluid, and measures the glucose contained therein.
Two of the biggest challenges were related to optimising the layout, such as finding the right distance between the sensors to prevent signal interference, and picking the right ultrasound gel for the BP sensor to prevent its leakage into the hydrogels of the other two sensors.
The team is already working on adding more sensors to the patch and making it fully wireless.
Source: ucsdnews.ecsd.edu
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