Technology has always been closely related to human body. From sharpened flint to smart phones, we carry thousands of years of development culture. But the relationship between humans and technology is about to shrink further - the next generation of electronic devices may not be just as simple as being close to our bodies, they can be powered by the human body.

Living is actually a waste of energy. To keep us alive, our bodies burn 2,000 to 2,500 calories a day, enough to drive a moderately used smartphone. So if a small fraction of that energy can be siphoned, our bodies can theoretically power most electronic devices, from medical implants to electronic contact lenses, without requiring any battery. Recently, researchers have taken an important step in the direction of unlocking the mystery of this potential.

Untapped potential
The first thing to say is that there are various forms of energy in our bodies. Most of the energy needs only a few operations, and they can be used to power the electronic equipment. But not all energy is available. A living organism is a conductive volumetric conductor. When there are electrical changes in some cells or tissues, electric fields will be generated in this volume conductor. Therefore, the potential variation of the electric field can be induced in different parts of the electric field, and the magnitude and waveform are different.

For example, the mammalian ear contains a tiny voltage called an endocochlear potential. The so-called potential (EP) in this article refers to the electrical changes that occur when the cells or tissues of animals, especially nerves and muscles, are stimulated. A long time ago, it was found in the cochlea that there was a spiral cavity in the inner ear where the human body acquired hearing by converting pressure waves into electrical pulses (where the potential of the cathode changed more than that of the anode when the stimulus was closer to the threshold for excitation), producing a local potential (this The change of seed potential is confined to the stimulation area and its adjacent parts, that is, the inner ear, and does not spread outward, so it is called local response, the potential occurring is called local potential. The EP is hard to detect, only a tenth of a volt, but in theory it is powerful enough to power hearing aids and other hearing aids.

At the end of the day, the body may also be a mobile power source.

For a long time, because of the extreme sensitivity of the inner ear, obtaining this kind of EP inside the human body has been considered inconceivable. But what if it was a combination of solid surgical strength and pioneering technological innovation? Researchers in Massachusetts, USA, succeeded in doing so in 2012.

The team developed an "energy acquisition chip," which has only one nail size and is designed to extract electricity directly from EP. They used guinea pigs to test the chip. The researchers implanted it into the guinea pig and eventually succeeded in generating enough electricity to drive the radio transmitter in the guinea pig's inner ear. But the power generated by the chip, which is only about a nanowatt (billionth of a watt), is still too low to power an implant. Even so, the production of a nanowatt of electricity has made considerable progress compared with the previous, which is enough to prove that this theory can be achieved. If the power output prototype could be enhanced in the future, the inner ear's natural potential could one day be used in hearing aids. If it were bolder, it could in theory even allow implants to help prevent and treat diseases such as Meniere's disease.

However, apart from the cochlea, electrical energy that flows freely in our bodies is relatively rare (and may be found if we are lucky). Most bioenergy sources are locked into other forms. Recycling is, of course, a good way to release it.

We walk every day. Most of the energy in our bodies is used for muscle movement, heart beating, and breathing (I'm sure you'll agree with that, because these are all very important things). The two invention of bicycle generator or clockwork flashlight are converting this kinetic energy into electrical energy. There seems to be no new idea like this, but things are slowly getting more complicated.
Over the past few years, researchers have begun to develop materials that, in principle, are called piezoelectric, can generate electricity from human motion. When piezoelectric materials spontaneously generate electric charges, they will be exposed to stresses. These materials have been used in countless industrial applications, even small cigarette lighters (the kind of electronic sound you hear when you click is actually the sound of a piezoelectric crystal being hit). Now, their next area of application may be the development of fabrics that generate energy.
At the end of the day, the body may also be a mobile power source.

One of the most advanced is a synthetic rubber-based piezoelectric fiber invented in 2013 by a Sino-US collaborative research team, which can generate electricity using only the kinetic energy generated by human motion. When volunteers walked with a shoe pad made of this fabric, the electricity generated was enough to light 30 LEDs. What's more exciting is that when you stick this fabric on your shirt and walk, the electricity generated can even recharge a lithium-ion battery for an hour!