people are complicated Machines, with moving parts that bend, squeeze, stretch, flow, quiver, and throb. Scientists are now tapping into these sources of energy to solve a common problem plaguing sensors, wearables and implanted medical devices — the dreaded flat battery.
By designing self-powered devices that could be the solution, researchers have found that the human body itself can be a handy power source — just right to power the explosive growth of the wearables market. “Electroceuticals” are starting to challenge drugs in medicine, so more people will rely on devices like implanted electrical stimulators and pacemakers to stay healthy.
“Bio-batteries” and energy recovery could make these devices energy autonomous, eliminating the need for invasive surgery to replace dead batteries. As a bonus, this wireless world will avoid implanted charging cables from falling out or becoming infected — problems that are all too common today.
Scientists have been working on body-powered devices since the early 2000s—until now, the technology was too power-hungry for the tiny amounts of electricity that could be harvested from humans. But after two decades of advances, today’s devices consume extremely low energy, opening the door to countless ideas and prototypes that draw energy from people.
cellular power plant
Your cells are basically batteries — biochemical batteries that turn sugary fuel into energy. German start-up CELTRO is harnessing this living energy source by using arrays of microneedles to harvest tiny amounts of energy from hundreds of thousands of cells. CELTRO’s first product will be a tiny autonomous pacemaker. “Muscle contraction, like the heart, starts at one point and spreads throughout the heart muscle,” says CEO and co-founder Gerd Teepe. “The idea is to harvest energy at multiple points to take advantage of this avalanche effect.” In addition to harvesting energy, the multifunctional microneedles will be inserted into cardiac tissue to monitor the heart and provide a helping hand to restore pacing when needed. In 2021, CELTRO raised seed funding for a lab-based proof-of-concept study.
paper fuel cell
French start-up BeFC is making biobatteries with green credentials. Its fuel cells use layers of carbon, cellulose and glucose, plus some proprietary enzymes. Adding a drop of liquid — such as blood or urine — triggers a reaction that generates electricity. Paper patches could power single-use diagnostic devices and continuous monitoring sensors, such as blood glucose monitoring kits for diabetics. After use, the batteries can even be composted — unlike other tiny batteries that end up in bins or incinerated. BeFC is currently raising Series A funding and expects to launch its first products in 2024.
my trembling heart
CAIRDAC in Paris is designing a pacemaker powered by the heart itself. Its leadless pacemaker is housed in a capsule that houses a piezoelectric energy harvester — a pendulum that oscillates with heartbeat, blood flow, and vibration. The oscillations are converted to electrical energy and stored until the device senses that the heart needs a vibration to reset the rhythm. The startup recently raised €17 million (about $18.3 million) in Series A funding to continue preclinical testing and move to human trials.
Solar panels are becoming a common sight in homes, and they will soon light up medical technology too. Researchers at Monash University in Melbourne, Australia, have found that solar panels placed under the skin still generate 10 percent as much electricity as those in direct sunlight — enough to power ultra-low-power sensors. A few hours in the sun will allow the implanted temperature sensor to run for 24 hours, and the researchers say its optimal location is between the neck and shoulders.
Microturbines can harness blood flow and convert it into electricity, according to researchers at the University of Bern in Switzerland. They designed a torpedo-shaped turbine that could be implanted in the blood vessels of the heart to generate electricity from the flow of blood, like a hydroelectric power station. A big unsolved challenge is how to avoid blood clots forming on the blades of the turbine, but in laboratory simulations, the turbine produced enough energy to power a commercial leadless pacemaker.
Italian startup PiezoSkin says it has developed an ultra-thin piezoelectric skin patch that can both measure movement and draw energy from it. In one study, it used the patch to monitor neck movements in patients with dysphagia or dysphagia — but the company’s biocompatible film can also harvest energy from other body movements and vibrations for use in sensors and Wearable device.
Humans radiate about 100 watts of heat a day, and according to Swiss startup Mithras, harnessing this heat could power wearable biosensors and even implants. Its thermoelectric generators, called TEGs, generate electricity by exploiting the temperature difference between the human body and the environment. With a difference of 5 degrees Celsius, Mithras estimates, a 12-centimeter-square TEG skin patch could fully power a cochlear implant.
This article originally appeared in the January/February 2023 issue of WIRED UK magazine.
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