New battery introduction implantable human power supply equipment has been developed

According to foreign media reports, scientists are currently studying the use of piezoelectric effects, thermal energy conversion, electrostatic effects, and chemical reactions to convert mechanical, thermal, and chemical energy into electrical energy in the human body to power wearable or implantable devices.

In "I Sing the Body Electric", the poet Walter Whitman deeply describes the "action and power" of "beautiful, peculiar, breathing, and laughing muscles." More than 150 years later, MIT materials scientist and engineer Canan Dagdeviren and her colleagues are giving new meaning to the study of Whitman's poetry. They are studying a device that can generate electricity based on people's heart beats.

The current electronic capabilities are so powerful that the computing power of smart phones far exceeds the processing power of NASA's related manned equipment when the first astronauts were sent to the moon in 1969. Over time, the rapid development of technology has led to higher and higher expectations for wearable or implantable devices.

The main drawback of most wearable and implanted devices remains battery life, and their limited battery capacity limits their long-term use. When your pacemaker runs out of power, what you need to do is perform surgery to replace the battery. The fundamental solution to this problem may lie inside the human body, because the body is rich in chemical energy, heat energy, and mechanical energy. This has led scientists to repeatedly study how devices obtain energy from the human body.

For example, a person's movement while breathing can produce 0.83 watts of energy; The heat of the human body in a calm state is about 4.8 Watts; A person's arm moves up to 60 watts of energy. A pacemaker needs only five parts per million to last seven years, a hearing aid needs only one in a thousand watts to run for five days, and a watt of energy allows a smart phone to work for five hours.

Now Dagdeviren and colleagues are studying how to use the human body itself as a source of device energy. Researchers have begun testing wearable or implantable devices in animals and humans.

One of the energy collection strategies involves converting energy from vibration, pressure and other mechanical stresses into electrical energy. This method can produce so-called piezoelectric, usually used for speakers and microphones.

One commonly used piezoelectric material is lead zirconate titanate,, but its high lead content is cause for concern because lead is too toxic to humans. Dagdeviren said, "But if you want to break down the structure of the lead, you need to heat it to 700 degrees Celsius or more." Dagdeviren said, "You can never reach this temperature in the human body."

So far, the equipment has been tested on cows, sheep and pigs because the animals 'hearts are roughly the same size as human hearts. "When these devices are mechanically distorted, they generate positive and negative charges, voltages, and currents, so that they can be collected to charge the battery," Dagdeviren explains. "You can use them to run biomedical devices such as pacemakers. Instead of performing surgical replacement every six or seven years after the battery is exhausted. "

Scientists are also developing wearable piezoelectric energy collectors that can be worn on the knees or elbow joints, or placed in shoes, trousers or underwear. In this way, a person can generate electricity for electronic products when he walks or bends over.

When designing a piezoelectric element, there is no need for the most efficient material to generate electricity, which seems to be somewhat counter-intuitive. For example, the materials used by scientists may have only 2 <UNK> or less conversion efficiency, rather than selecting materials that can convert 5 <UNK> of mechanical energy into electrical energy. If it changes more, "it may be done by putting more weight on the body, but users certainly don't want to get tired," says Dagdeviren.

Another energy collection method is to use thermoelectric conversion materials to convert body heat into electrical energy. "Your heart beats more than 40 million times a year," Dagdeviren points out. All of this energy is converted into body heat and dissipated -- and this is exactly the kind of potential resource that can be captured.

There are indeed some major problems with human thermal power generation. This energy conversion method often depends on temperature differences, but the body's temperature often maintains a fairly constant state, so the temperature difference inside the body is not enough to generate a lot of electricity. However, if these devices can collect body temperature while being exposed to a relatively cool external environment, they can solve the problem.

Scientists are exploring thermal power plants for wearable devices, such as watches. In principle, the heat produced by the human body can generate enough electricity to provide wireless health monitors, artificial hearing aids, and cerebral cortex stimulators for Parkinson's disease.

In addition, scientists also try to power devices through the common electrostatic effect. When two different materials repeatedly collide or rub with each other, the surface of one material can seize electrons from the surface of another material and accumulate charges. This is called friction electrification. A key advantage of friction electrification is that almost all materials, including natural materials and synthetic materials, generate static electricity, which provides researchers with many possibilities to design a variety of gadgets.

"The more I study friction electrification, the more exciting it becomes, and the more it is likely to be used," says Wangzhonglin, a nanotechnology expert at Georgia Institute of Technology, co-author of the paper. "I can see myself working on this research for the next 20 years. "

Different materials have very different amounts of electricity generated by friction, so scientists are experimenting with various materials. The researchers created a cube grid similar to a microscopic city block, similar to the nano-wires of the bamboo forest, and a pyramid array similar to the Great Pyramid of Giza. Wang said the materials not only "look beautiful", but that covering the surface with a pyramid array could increase power generation by five times as much as a tablet.

Researchers have tested pacemakers, heart monitors and other implantable devices powered by respiration and rapid heartbeat in mice, rabbits and pigs. "We are also studying the possibility of using friction electricity to stimulate cell growth and accelerate wound healing," Wang said. "In addition, we have started friction electricity experiments on nerve stimulation to see if we can make any contribution to neuroscience. "

Wang and his colleagues have also designed wearable devices for friction electrification. For example, they have made friction tapes that can charge flexible wristbands with lithium-ion batteries. The gadget can provide electrical power to a wearable heart rate meter that uses Bluetooth technology to wirelessly transmit its data to smart phones. "The mechanical energy generated by the daily movement of the human body can be converted into electricity through our fabric," Wang said.

Another strategy relies on a device called a biofuel cell device that produces electricity through a chemical reaction between the enzyme and energy storage molecules in the body (eg, glucose in the blood), or lactic acid secreted in sweat. For example, a cellulose hexose dehydrogenase extracted from fungi decomposes glucose and produces electricity in a nanometer (billionth of a meter) carbon tube.

The choice of enzyme can be tricky. For example, although many scientists have found that glucose oxidase can produce electricity in biofuel cells implanted in experimental mice, the enzyme also produces hydrogen peroxide (a common bleach component), which may Will deteriorate the performance of the device and cause damage to the body.

In another study, scanning electron micrographs showed that carbon nano-tubes used in experimental biofuels cells can generate electricity from the body. These test tubes are coated with enzymes that can handle natural energy molecules, such as lactates in sweat or glucose in the blood. This tool is electrically active and at the same time provides a huge surface area for the enzyme-energy reaction, allowing more electricity to be generated in a certain volume.

French scientists have also created a bio-fuel cell based on enzyme-coated carbon nano-tubes, which is about half a teaspoon in size. When implanted in mice, it can generate enough electricity to power LED or digital thermometers by reacting with blood sugar. Experiments have also shown that fabric biofuel cells woven into headbands and wristbands can generate enough electricity to power watches through the chemical reaction of lactic acid and enzymes in sweat.

As far as Dagdeviren knows, these devices are not yet available on the market. But she predicts that the technology will be marketed in less than a decade. In the future, energy gathering devices may become more suitable for the human body. Dagdeviren and her colleagues are even working on degradable power generation gadgets.

"Imagine," she said, "inserting a device into your body, and it will degrade into molecules and dissolve into body fluids after a period of work. You don't have to open your chest to remove it: We can use biodegradable materials, such as filaments and zinc oxide, that decompose over time. "

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