A battery that never runs out of power. How is it powered?

Humans are complex machines with moving parts that surprise in many ways. Scientists are of the same opinion that the potential of man is infinite. Scientists and technology developers are ready to use the human body as an endless source of energy. If successful, it would solve the major problem of smaller wearable devices, such as smart watches, headphones, medical and similar devices, which often run out of power at the wrong time.

Devices with a certain degree of autonomy, including automatic battery charging, are the future. The only question is, where to draw the energy that is omnipresent and "infinite"? Scientists have come to the conclusion that the human body can be a convenient source of power. The finding came at the right time, as the market for wearable devices has exploded in recent years.

The so-called “electroceuticals” opposes classical pharmacy and medicine, because experts predict that more and more people dependent on wearable devices for monitoring and maintaining health, such as implanted electrostimulators, pacemakers, blood pressure and heart rate monitors.

"Biobatteries" and the process of collecting energy from external sources could make such devices energy autonomous, thereby eliminating the need for invasive interventions to replace empty batteries. At the same time, we would reduce the possibility of incorrectly implanted devices, their infection or unwanted subsequent movements.

Since the beginning of the second millennium, the profession has been developing devices that can be powered by the human body. So far, there have been no major successes. The technology or devices were simply too muchč consuming minimal amounts of electrical energy that can be obtained through the natural processes of the human body. After two decades of effort, however, experts managed to make a major leap. Thanks also go to the developers of wearable devices, who in the last 10 years have managed to create devices that consume an extremely small amount of energy. With this, they opened the door wide to ideas and prototypes that can take advantage of the power of our bodies.

A power plant powered by cells

Simply put, cells are biochemical batteries that convert sweet fuel into energy. German startup Celtro harnesses this energy source by using arrays of microneedles that can extract small amounts of energy from most batteries. one hundred thousandč cells. The first product of the German company will be a small autonomous pacemaker. "Muscle contraction, like the heart, starts at one point and then spreads throughout the heart muscle," says CEO and co-founder Gerd Teepe. “Our idea was to collect energy on more points, with a timer we would take advantage of this wave action of the muscle.” In addition to harvesting energy, several dedicated microneedles will be inserted into the heart tissue to monitor the heart and provide assistance; with electrical stimulation to restore heart rhythm when necessary. In 2021, Celtro successfully raised enough funds to start laboratory studies to prove the concept's applicability.

Paper fuel cells

French startup BeFC is developing biobatteries with green credentials. This means that the fuel cell uses layers of carbon, cellulose, glucose and some proprietary enzymes. Adding a liquid, such as blood or urine, triggers a reaction that produces electricity. Their product, in the form of paper patches, could power disposable diagnostic devices and sensors for continuous monitoring of conditions, such as glucose monitoring kits for diabetics. After use, the fuel cells can even be composted, unlike other miniature batteries that eventually end up in landfills. BeFC is currently in the fundraising phase. They expect to come to the market with their products in 2024.

#141 central stimulator with piezoelectric energy collector

CAIRDAC, based in Paris, is developing a pacemaker powered by the patient's heart. The waterless pacemaker is packaged in a capsule containing a piezoelectric energy harvester “#128;“ a pendulum that swings through heartbeat, blood flow and vibration. The oscillations are converted into electricity and stored until the device detects that the heart needs a jolt to reset the rhythm. The startup company recently raised 17 million euros to continue preclinical testing and transition to human trials.

Powering sensors and implants with solar energy?

Solar cells have spread to many household roofs in the last two years. Even in Slovenia at one point there was a long waiting line for the establishment of an independent solar power plant. Researchers from Monash University in Melbourne have found that a solar panel placed under the skin is capable of producing up to 10 % of solar panel energy in direct sunlight. This is enough to power devices with extremely low consumption. A few hours of charging in the sun would be enough for the 24-hour operation of a temperature sensor that can be implanted in the human body. According to the researchers, the optimal place for implanting the solar panel is between the neck and the shoulder.

Hydroelectric heart

Mini-turbines could harness blood flow and convert it into electricity, at least that's what the University of Bern is finding out. Researchers there have designed a torpedo-shaped turbine that could be implanted in a blood vessel in the heart and thus establish a way of generating electricity using blood flow, in a similar way to how hydroelectric power works. A major challenge they are actively tackling is how to avoid the formation of blood clots on the turbine blades. In laboratory tests, their turbine was able to generate enough energy to power commercially available waterless pacemakers.

Piezoelectric patch

Italian startup PiezoSkin claims to have developed an ultra-thin piezoelectric skin patch that can simultaneously measure human movements and draw energy from them. In one of the studies, the patch was used to monitor the movement of the neck in people with dysphagia (swallowing problems), but it could also be used to monitor and pump the muscles with the help of other body movements and vibrations. Similar to the other prototypes, PiezoSkin patches could also produce enough energy to power smaller devices.

Heat supply?

On average, the human body emits 100 watts of thermal energy per day, which, according to the Swiss company Mithras, could be enough to power wearable biosensors and implants. Their thermoelectric power supplies, known as TEGs, generate electrical energy by exploiting the temperature difference between the body and the environment. The company estimates that their TEG skin patch with a temperature difference of 5 degrees Celsius could fully power a cochlear implant.