Although new developments are announced almost daily, wearable sensors promising to personalize medicine by constantly monitoring people’s vital signs during their daily activities have yet to hit their stride. That could finally change thanks to the efforts of a group of researchers at the University of California at San Diego led by professor of nanotechnology Joseph Wang. Through their work, healthcare professionals who aspire to tailor treatment to a person based on their vital data – not just heart rate, but also cholesterol levels, glucose, caffeine, lactates, erythrocytes , white blood cell count and blood pressure – may soon have access to an all-in-one patch capable of collecting and transmitting these signals in real time.
“We can correlate your daily activities, see if your blood pressure goes up or down when you drink alcohol, a cup of coffee, exercise or when you eat a meal,” says Lu Yin, co. – author of a new study describing the portable device. “This patch will allow us to study your body’s response to these activities more closely and in real time. By observing the correlation between the dynamics of biochemical and biophysical data, we can not only understand how people respond to what they eat and environmental conditions, but also become aware of subclinical manifestations that can lead to possible disease. Because it can be worn on the wrist or neck and can potentially communicate wirelessly with off-the-shelf digital devices, like smartwatches and laptops, Yin says, the device promises to have applications in others. areas, such as sports and entertainment, for monitoring athletic performance and fatigue.
Professor Wang’s research into wearable devices began in 2016. That year, his lab introduced a portable proof-of-concept network, dubbed Chem-Phys, to detect biometric information. He demonstrated that it is possible to group several large sensors on a miniaturized patch without the signals interfering. But while the idea sounded good in 2016, the engineering wasn’t there for scale-up just yet.
“This is the first time that biometric and biological sensors have been grouped together on the same patch.”
Recently, however, Wang and his team have further advanced technology by developing a wearable skin-like patch, which is both flexible and elastic and can monitor cardiovascular signals and several biochemical measurements like lactate, glucose, and blood glucose. alcohol in the body at the same time. . “This is the first time that biometric and biological sensors have been grouped together on the same patch,” explains Yin.
To design a functional patch that actually works, several technical issues had to be addressed, including the issue of crosstalk between biodynamic sensors such as heart rate and blood pressure monitors with biochemical sensors for glucose, alcohol, caffeine and lactate. To combine rigid ultrasound transducers with electrochemical sensors, they used liquid ultrasound gel. But if the gel leaked and encountered other sensors, it would cause interference. So they used a solid ultrasound gel which works well but does not generate electromagnetic interference. They also had to calculate the optimal distance between the blood pressure sensor and the chemical sensors. They found that a 1cm spacing was enough to prevent signal leakage while still keeping the device small enough to be worn comfortably.
Tensile flexibility and stability were two other issues to be addressed. Once applied to a subject’s epidermis, the impedance of the chemical sensor and the contact resistance of the ultrasound transducers could be affected by the torsion and pressure, which normal movement of the body can produce when bending and pushing. flexing.
They overcame this hurdle by mounting and gluing the ultrasonic transducers to a plastic substrate while wetting the surfaces of the printed electrodes with toluene, an industrial solvent. “This means that stretching and other deformations do not affect the shape of the waves recorded by the ultrasonic transducer,” says Lin.
“These systems will allow a doctor to closely monitor patients’ vital signs, much like a mechanic does today with a car from his dashboard.”
During the test, subjects wore the patch on their neck while performing various tasks in sequence, including eating a sugary meal, riding a stationary bicycle, and drinking alcoholic and caffeinated beverages. The patch produced readings that clearly matched those obtained with traditional monitoring devices such as a breathalyzer, blood pressure cuff, blood lactate meter, and glucometer. Instead, laboratory analyzes of the subjects’ sweat were used to confirm the caffeine levels measured by the sensor.
“There is no doubt that biosensors like those at UC San Diego will advance telemedicine and prevention,” said Michael Snyder, director of the Stanford Center for Genomics and Personalized Medicine, who was not involved in the research. “These systems will allow a doctor to closely monitor patients’ vital signs, much like a mechanic does today with a car from his dashboard.”
He added, however, that resolution and signal functionality issues, such as portability and heaviness, still hamper their use in non-institutional environments. This patch is still nowhere near as stylish and wearable as an Apple Watch or Oura ring. Despite this, Snyder believes that Chem-Phys or something like that will become a single biometric device that people wear to broadcast all kinds of real-time remote feedback on their condition to their doctors, the cockpit, or ultimately. to their trainers, personal leaders and therapists. But the first goal is to enable physicians to discover and prevent adverse events earlier, thereby improving the health of their patients and saving lives.