How about recharging your batteries... with your body?

Researchers are working on the possibility of harvesting energy via a thermoelectric generator, which would make it possible to use body heat as a source of supply for certain terminals and connected objects. But the challenges are many.

In the space of twenty years, smartphones have become incredibly large and thin. They are also now much more powerful than the mobiles we had in our pockets. All this, thanks to the continuous miniaturization of components. But this development has taken place to the detriment of a characteristic that is nevertheless central to mobiles: operating autonomy.

Modern smartphones today hardly last beyond a day or two after a full recharge. Inevitably, between the large screen – which can also be very bright –, 4G communication, video or games, uses such as components are not really likely to save battery power. It can melt like snow in the sun.

That doesn't leave much room for the battery, all that.

So what to do? Should we stop thinning phones to leave a little more room for batteries? Should we put an end to the fashion for very large screens? These are perhaps not the most desirable tracks, especially since the public has become acclimatized to these new technological prescriptions, which act as a ratchet effect: impossible, therefore, to go back.

What if the answer is not in the smartphone but outside? Rather than playing on the size of the screen or the thinness of the terminal, shouldn't we find a way to be able to harvest energy from an external source to then convert it into electric current and reinject it into the mobile? , in order to supply the components? This is what scientists are trying to do.

CC Dispatch Tribunal

How ? Simply by taking advantage of body heat.

Man is an endothermic organism, that is to say, he produces a temperature thanks to his metabolism. However, this heat could be a source of energy to recharge a battery – or in any case extend its life. It is this approach that interests several American professors and engineers, in particular the team at North Carolina State University.

This track has a few advantages, starting with the fact that it does not require you to be in motion to capture energy. The heat production is constant, whether you are seated or active. Prototypes have thus been designed, by slipping them at the level of a t-shirt or placing them at the level of the biceps. Our colleagues from The Verge focused on this work.

Thermoelectric generator prototypesCredit: North Carolina State University

In theory, this approach could be used to power all kinds of connected accessories, such as a high-tech watch or a fitness bracelet (two products which have the advantage of being in almost constant contact with human skin, including with body temperature). In the case of a smartphone, it is obviously a little more complicated.

Other reflections are being studied, such as the possibility of generating electricity via the friction of two pieces of clothing, for example.

The problem with a thermoelectric generator type approach is that it has to be really, really efficient to make a difference. One of the prototypes designed in the USA is only capable of generating energy of a few microwatts; insufficient to properly power a terminal, especially if behind the user intends to turn on 4G or launch a video game.

Interesting for a connected watch? CC Andri Koolme

Also the scientific community considers that it is necessary to play on two levels: firstly by creating and optimizing the energy harvest, to capture as much energy as possible in order to be able to inject a maximum of it into the telephone; then, to ensure that the terminals are able to operate with the least possible drain on the battery.

Also, these researchers will certainly follow the development of 5G with interest. Indeed, the next mobile telephony standard, which should begin to emerge in 2020, should make it possible to multiply the operating time of connected objects by ten on a single charge. Which, in the age of ultra-thin and ultra-large devices, can't hurt.