Ever since Nikola Tesla and Tomas Edison gave us the light bulb and other electric inventions, people have been looking for better ways to utilize electricity and power our devices. Thanks to decades of research, humanity reached various levels of development in technology, mainly in energy and electronics. While the search for better power sources gave us things like electric utility services, batteries, wind turbines and solar panels, scientists have always wondered how we can generate electricity just by existing.
Can you imagine keeping your smartphone charged by using it? What if we could charge our devices by tapping our fingers while we listen to music or wearing clothing that senses our pulse? These things might sound like something straight out of a science fiction novel, but they already exist! We present to you nanogenerators! What are these revolutionary things? Find out below.
What are nanogenerators?
If you don’t know what nanogenerators are, you’re not the only one. This relatively unknown word is used to describe small electronic chips that generate electricity by utilizing the movement of the body (tapping, pinching, etc). Chips in nanogenerators have integrated circuits placed in a flexible surface, not unlike the circuit boards in your computer. As their name implies (the prefix “nano” is used for technology measured in nanometers, one billionth of a meter) these generators are super small, and even the most powerful and complex ones among them can be held between your index finger and thumb.
Sure, nanogenerators are tiny and responsive, but that’s not all. They can be very powerful. For instance, in one experiment, researchers used five nanogenerators stacked together to produce a current of about one microampere (three volts of energy) the equivalent of two AA batteries. If we consider the size of these generators, that is a pretty impressive performance.
Types of nanogenerators
There are three main types of nanogenerators in existence. The first one we’ll mention is piezoelectric nanogenerators which use the piezoelectric effect to produce energy. This effect creates an electric field in response to material deformation (piezein means press in Greek). As the crystalline structure of the material changes, polarized molecules also change position and produce electricity. The deformation needed for energy production can come from direct pressure or through vibration.
The second type of nanogenerators is triboelectric nanogenerators. As their name suggests (tribo means rub in Greek), these generators use the triboelectric effect in which electrons create a difference in potential by being transferred from one material to another. Scientists from the City University of Hong Kong developed a new triboelectric nanogenerator using a slippery surface which boosts the generators ability to harvest energy. This new discovery may change the face of energy harvesting devices and provide them with better stability and durability.
There are also pyroelectric nanogenerators that use the pyroelectric effect to generate voltage via a heat differential. When a certain material is heated, it triggers voltage generation due to positional changes of polarized atoms.
What are they made of?
Nanogenerators can be made out of different materials depending on the method of energy collection. For instance, the team of researchers from the Georgia Institute of Technology lead by Professor Wang Zhonglin is focusing on piezoelectric nanogenerators that employ Zinc Oxide nanowires. Other research teams use different approaches by choosing zirconate titanate forming it into nanoribbons and creating a wave-like pattern. Almost all materials in the world exhibit the triboelectrification effect (metal, polymer, silk, wood, etc.) so the materials choices for these generators are huge.
The range of uses of nanotechnology is getting bigger every year, from wearable electronics to various sensors. However, the innovations in biomedicine have the opportunity to bring many improvements to human lives. Since implantable medical devices require a reliable and constant source of power (battery packs can only be replaced by surgery which is too invasive), the kinetic energy of body movements, breathing and heartbeat can provide enough energy to be picked up by piezoelectric nanogenerators. Also, even the tiniest of movements produce friction that can power triboelectric nanogenerators while the body produces a lot of heat that pyroelectric nanogenerators can use as fuel. Therefore, the human body is a great host for nanogenerators and biomedicine can make great use of them.
Recent years brought us major advances in nanogenerator development and there are no signs of stopping in the future. From implants to wearable tech, these tiny generators promise big things for all humanity.