Portable electronic devices are excellent tools for monitoring health, but it has been difficult to find convenient power sources for them.
Now a group of scientists have successfully developed and tested a portable biofuel cell array that generates electrical energy from lactate in the user’s sweat, opening the door to electronic health monitoring powered solely by bodily fluids.
It cannot be denied that, in recent decades, the miniaturization of electronic devices has made great strides.
Today, after pocket smartphones that could put old desktops to shame and a host of options for wireless connectivity, there is one particular type of device whose development has steadily advanced: portable biosensors.
These small devices are generally designed to be worn directly on the skin to measure specific biological signals and, by sending measurements wirelessly to smartphones or computers, to track the health of the user.
Although materials scientists have developed many types of flexible circuits and electrodes for portable devices, finding a suitable power source for portable biosensors has been a challenge.
Traditional button batteries, such as those used in wristwatches and pocket calculators, are too thick and bulky, while thinner batteries would pose capacity and even safety issues. But what if we were the power sources for portable devices?
A team of scientists led by Associate Professor Isao Shitanda of the Tokyo University of Sciences, Japan, is exploring efficient ways to use sweat as the sole source of energy for wearable electronic devices.
In his most recent study, published in the Energy Sources Journal, present a novel design for a biofuel cell matrix that uses a chemical in sweat, lactate, to generate enough energy to drive a biosensor and wireless communication devices for a short period of time.
Your new biofuel cell matrix looks like a paper bandage that can be worn, for example, on the arm or forearm. It consists essentially of a hydrophobic paper substrate on which multiple biofuel cells are placed in series and in parallel; the number of cells depends on the output voltage and the power required.
In each cell, electrochemical reactions between lactate and an enzyme present in the electrodes produce an electric current, which flows into a general current collector made of a conductive carbon paste.
This is not the first lactate-based biofuel cell, but a few key differences make this new design stand out from existing lactate-based biofuel cells.
One is the fact that the entire device can be manufactured by screen printing, a technique generally suitable for cost-effective mass production. This was made possible by careful selection of materials and ingenious design.
For example, whereas earlier similar cells used silver wires as conductive paths, current biofuel cells employ porous carbon ink. Another advantage is the way lactate is delivered to cells.
Layers of paper are used to collect sweat and transport it to all cells simultaneously through the capillary effect, the same effect by which water travels rapidly through a napkin when it comes into contact with a puddle of water.
These advantages make biofuel cell arrays exhibit an unprecedented ability to deliver power to electronic circuits, as Dr. Shitanda comments: “In our experiments, our paper-based biofuel cells could generate a voltage of 3.66 V and a 4.3 mW output power. As far as we know, this power is significantly higher than that of previously reported lactate biofuel cells. “
To demonstrate its applicability for portable biosensors and electronic devices in general, the team manufactured a self-powered lactate biosensor that could not only feed using lactate and measure the lactate concentration in sweat, but also communicate the measured values in real time to a phone. smart. via a Bluetooth low energy device.
As explained in a previous study also led by Dr. Shitanda, lactate is an important biomarker that reflects the intensity of physical exercise in real time, which is relevant in the training of athletes and patients in rehabilitation.
However, the proposed biofuel cell assemblies can power not only portable lactate biosensors, but also other types of portable electronic devices. “We managed to drive a commercially available activity meter for 1.5 hours using a drop of artificial sweat and our biofuel cells,” explains Dr. Shitanda, “and we hope that they will be able to power all kinds of devices, such as smart watches and other common portable devices “.
Hopefully, with more developments in portable biofuel cells, powering portable electronic devices and biosensors will not be a problem.
(LOOK the video explaining this story below).
Source: Tokyo University of Sciences
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