Do you have batteries? I’m not sweating! Wearable biofuel cells now generate electricity from lactic acid-

Scientists are developing biofuel cells that can use purely human sweat to power wearable electronics

Wearable electronics and biosensors are great tools for monitoring health, but finding a convenient power source for them has been difficult. Currently, a group of Japanese scientists have successfully developed and tested a wearable biofuel cell array that produces electricity from the lactic acid in the wearer’s sweat, opening the door to electronic health monitoring powered solely by body fluids. ..

It is undeniable that the miniaturization of electronic devices has made great strides in the last few decades. Today, there are certain types of devices that are steadily developing, after pocket-sized smartphones that can embarrass older desktop computers and numerous options for wireless connectivity. It is a wearable biosensor. These small devices are typically intended to be worn directly on the skin to track a user’s health by measuring specific biological signals and wirelessly transmitting the measurements to a smartphone or computer. ..

Materials scientists have developed many types of flexible circuits and electrodes for wearable devices, but finding the right power source for wearable biosensors has been difficult. Traditional coin cell batteries, such as those used in watches and pocket calculators, are too thick and bulky, but thin batteries pose capacity and safety issues. But what if we were the power source for our wearable devices?

A team of scientists led by Associate Professor Isao Shimoda of Tokyo University of Science is looking for ways to efficiently use sweat as the only power source for wearable electronic devices. A recent study published in the Journal of Power Sources found a biofuel cell array that uses chemicals in sweat and lactic acid to generate enough power to drive biosensors and wireless communication devices for short periods of time. Introducing a new design. This research was conducted in collaboration with Dr. Seiya Tsujimura of University of Tsukuba, Dr. Tsutomu Mikawa of RIKEN, and Dr. Hiroyuki Matsui of Yamagata University.

Their new biofuel cell array looks like a paper bandage that you can wear on your arm or forearm, for example. It essentially consists of a water repellent paper substrate with multiple biofuel cells arranged in series and in parallel. The number of cells depends on the output voltage and power required. In each cell, an electrochemical reaction between lactic acid and the enzymes present in the electrodes creates an electric current that flows through a common current collector made of conductive carbon paste.

This is not the first lactate-based biofuel cell, but with some important differences, this new design sets it apart from existing lactate-based biofuel cells. One is the fact that the entire device can be screen-printed. This is a generally suitable technique for cost-effective mass production. This is made possible by careful selection of materials and an ingenious layout. For example, similar previous cells used silver wire as the conductive path, but today’s biofuel cells use porous carbon ink. Another advantage is the way lactic acid is delivered to the cells. A layer of paper is used to collect sweat and transport it to all cells at the same time by capillarity. This has the same effect as water quickly passing through the napkin when it comes into contact with a puddle.

With these advantages, biofuel cell arrays offer unprecedented ability to power electronic circuits.In our experiments, paper-based biofuel cells were able to generate a voltage of 3.66V and an output power of 4.3mW. As far as we know, this output is significantly higher than the output of previously reported lactate biofuel cells.To demonstrate its applicability to wearable biosensors and common electronic devices, the team can use lactic acid to power and measure lactic acid levels in sweat, as well as low power measurements in real time. Smartphone via Bluetooth device.

Lactic acid is an important biomarker that reflects real-time exercise intensity associated with training athletes and rehab patients, as explained in a previous study also led by Dr. Citanda. However, the proposed biofuel cell array can power not only wearable lactate biosensors, but also other types of wearable electronics. “With a drop of artificial sweat and a biofuel cell, we were able to drive a commercial activity meter for 1.5 hours,” explains Dr. Citanda. “It should be able to power all kinds of devices, including smartwatches and smartwatches. Other common portable gadgets.”

Hopefully, with the further development of wearable biofuel cells, powering portable electronic devices and biosensors will not sweat!


Original Paper Title: High Power Paper-Based Lactate Biofuel Cell Array
Journal of Power Sources
DOI: 10.1016 / j.jpowsour.2021.229533 Do you have batteries? I’m not sweating! Wearable biofuel cells now generate electricity from lactic acid-

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