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The ranks of wearable biomedical sensors replenished with a new Designed by engineers from the University of California, San Diego: a small electronic tattoo is attached to the human body and monitors his state of health during physical training. Eat the device will be from human sweat, which is abundant stands out under medium and high intensity loads. Scientists described their development in a report that they read at the 248th annual meeting of the american chemical community. Principle device operation is based on the determination and response of sensors to lactic acid is a substance present in sweat. “Lactate levels can tell a lot about the state of the body during exercise time, “explains the lead author of the study. Wenzhao Jia The more intense the training, the more lactic acid is produced. During strenuous physical the body must generate more energy, therefore a process called glycolysis is activated. During it energy is produced and lactate is released, which can be detected in blood. The problem is that to keep track of the level physical activity the amount of lactic acid in the blood it is necessary to analyze quite often during different physical loads. And collecting samples and analyzing them takes a lot of time and effort. Therefore, Jia and her colleagues have developed the most convenient A method of measuring lactate content during exercise. They implanted a small flexible sensor into a stretch film, which can be attached to the skin as a temporary tattoo. Sensor contains an enzyme that traps electrons from lactate, generating a weak electric current. For testing technology researchers invited to their laboratory 10 healthy volunteers and attached to their skin the newly invented sensors. During the experiment, scientists measured the electric current, which produced the device during physical training subjects – they pedaled the exercise bike for half an hour with a gradual increase in resistance. Thus, researchers were able to continuously monitor lactate levels in sweat over time and with changing exercise intensity. Jia and her team later decided to turn sweat into a power source. bioaccumulator. Batteries produce energy when current flows through the form of electrons from the anode to the cathode. In this case, the anode contained an enzyme that extracted electrons from lactate, and the cathode contained the molecule that took the electrons. Fifteen volunteers who trained on a stationary bike with a tattoo on the body, produced various amounts of electricity. Interesting that those who trained on average less than once a week, produced more energy than those who were subjected to physical exertion from one to three times a week. The least energy was produced by those who prefers almost daily sports. Maximum performance recorded among volunteers from the “unsportsmanlike” group, amounted to 70 microwatts per square a centimeter of skin. “It’s not so much in the usual sense, but we already working on increasing the device’s potential. The end result we need to bring technology to the point where sweat can feed small electronic devices. Right now we can get 70 microwatts per square centimeter maximum, but our electrodes are only 2-3 millimeters wide and generate about 4 microwatt. For food, for example, hours, at least 10 are required microwatts, “explains Jia. In the future, scientists also have to decide the problem of energy storage and its reasonable consumption. However their bioaccumulator already has great advantages over analogues: it is biocompatible, does not emit toxic substances and uses renewable energy.
Time
