Peel the Power
Engineers made an energy harvester from little more than a few pieces of Scotch tape, and it is capable of powering hundreds of LEDs.
The rise in popularity of portable and wearable electronic devices is creating a need for smaller and more efficient sources of energy. These devices are neither portable nor wearable if they are saddled with bulky or heavy batteries, and if they need to be recharged too frequently they are more likely to wind up in a junk drawer than on a wrist or in a pocket. Unfortunately, battery technology has not yet caught up with other technological advances in this space.
But this is not to say we are out of luck until a quantum leap in battery design takes place. Researchers are increasingly looking at energy harvesting, for example, to keep our mobile devices powered up. Have you ever considered how much energy is wasted in our everyday activities? With every step we take, energy is dissipated in the springy materials of our shoes and the heat that emanates from our bodies. Modern energy harvesting techniques offer the promise of reclaiming some of that energy to power our devices.
These technologies do not necessarily have to be complex or expensive, either, which means that they have the potential to be deployed widely. Researchers at The University of Alabama in Huntsville, for instance, have demonstrated how meaningful amounts of electricity can be produced with little more than a few pieces of tape. By repeatedly separating them and sticking them back together, the team demonstrated that hundreds of LEDs, and even a laser, could be supplied with power.
The team’s energy harvester is a type of triboelectric nanogenerator (TENG), a device that transforms mechanical energy — like motion, vibrations, or friction — into electricity using the triboelectric effect. This effect occurs when two different materials come into contact and then separate, transferring charge and creating a voltage.
The TENG is constructed by sandwiching Scotch tape and electrode layers between two 3D-printed plastic plates. A small mass is attached to the upper plate, and vibrations are applied to the lower one using a shaker table. As the device vibrates, the tape layers repeatedly make and break contact, generating electricity with every cycle. This system can operate at high frequencies — up to 300 Hz — greatly enhancing its power output and expanding its potential uses when compared with other existing TENGs.
At its peak, the new TENG produced 53 milliwatts of power, enough to illuminate 350 LEDs or power a laser diode. This was achieved by optimizing the combination of tape types to increase the density of the contact points between the acrylic adhesive and the polypropylene backing layer, narrowing the atomic gaps and enhancing the triboelectric effect.
Beyond lighting LEDs, the researchers also demonstrated the device’s utility in some real-world applications. They built a self-powered biosensor that can detect human arm movements, which is ideal for monitoring muscle activity in athletes or patients, and an acoustic sensor capable of detecting sound waves. Notably, the biosensor design avoids direct skin contact, reducing the risk of irritation and ensuring more consistent readings.
The researchers believe that with further refinement, their tape-based triboelectric generators could power an array of small electronic systems. Their simplicity, affordability, and compatibility with high-frequency vibrations make them attractive for use in wearables, environmental sensors, and battery-free monitoring systems.