Chinese Scientists Make Charging Phones with Body Heat Possible

Plastic is a marvel of modern materials science – versatile, durable, and lightweight. It can be molded into countless shapes, resists corrosion, and is incredibly cost-effective, making it ubiquitous in our daily lives from food packaging to furniture.

However, most plastics don’t conduct electricity, which is a big problem in many situations. This means they can’t be used for electrical wiring, they can build up static electricity (which can damage electronics), and they can’t help get rid of heat in devices. It also means we can’t use them for things like touch screens or protecting equipment from electromagnetic interference. Because of this, we often have to use metals instead, which can make things heavier, more expensive, and harder to design.

Now, in a groundbreaking development, researchers from Chinese Academy of Sciences have created a new type of plastic material that could revolutionize how we power our everyday devices. This innovative material can efficiently convert waste heat into electricity, potentially allowing your smartwatch to charge from your body heat or your refrigerator to power itself from its own heat emissions.

The key to this breakthrough, recently published in Nature, lies in what scientists call “conjugated polymers” – special types of plastics that can conduct electricity. Think of these polymers as tiny, flexible wires woven into the fabric of the plastic. Until now, these materials weren’t efficient enough for practical use, but Chinese researchers has found a way to dramatically improve their performance.

The scientists achieved this by creating what they call a “polymeric multi-heterojunction” structure. While this term might sound complex, you can imagine it as a carefully layered sandwich of different plastic materials. Each layer is incredibly thin – less than ten nanometers, which is about 10,000 times thinner than a human hair.

This layered structure does two important things. First, it scatters heat (which scientists call phonons) like a pinball machine, making it hard for heat to move through the material. This is crucial because it helps maintain a temperature difference, which is necessary for generating electricity. Second, it allows electrical charge to flow efficiently, like a well-designed highway system for electrons.

The effectiveness of thermoelectric materials is measured by something called the “dimensionless figure of merit” or ZT. It’s like a report card for these materials – the higher the ZT, the better. The new plastic material achieved a ZT of 1.28 at about 95°C (203°F), which is higher than many conventional thermoelectric materials and a record for flexible materials.

To put this in perspective, this performance is better than the thermoelectric materials used in some spacecraft and specialized cooling systems. But unlike those materials, which are often rigid and contain rare or toxic elements, this new plastic is flexible, non-toxic, and can be produced at a lower cost.

Perhaps most excitingly, the researchers demonstrated that this new material can be produced using solution coating techniques. This is similar to how newspapers are printed in large rolls, meaning it could be manufactured on a large scale relatively easily and cheaply.

This breakthrough opens up a world of possibilities for Internet of Things – the network of everyday objects embedded with electronics. Imagine a future where your clothes generate electricity from your body heat to power health monitors, or where industrial pipes convert waste heat into useful electricity.

While there’s still work to be done before we see these plastics in our everyday lives, this research represents a significant step towards a future where we can harvest energy from heat that would otherwise go to waste. It’s a promising development in our quest for more sustainable and efficient energy solutions.