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19-11-2021 | | Robin Mitchell

Recently, researchers have developed a generator that can use the heat generated by a fever to power basic wearable devices. What are the challenges of a typical thermoelectric generator, what did the researchers prove, and is it critical to power future medical devices?

Thermoelectric generators are often news, and researchers are trying to miniaturize them, hoping that they can become wearable devices. If successful, the wearable TEG can use only body heat as an energy source to power mobile devices indefinitely. This will eliminate the need for charging stations for devices, powering smart medical devices, and even providing medical implants.

However, the truth about TEGs is that they are extremely inefficient and generate very little power. There are many reasons why TEGs can't work. These factors must prove that human beings are very poor in energy.

The first factor is that TEG needs a temperature gradient to generate electricity, and the temperature difference between human skin and room temperature is almost not great (up to 10°C to 15°C). In hot countries where the ambient temperature may be lower than the skin temperature, this temperature gradient can get worse. 

The second factor is that TEG is naturally an inefficient device; the efficiency of a typical TEG is about 5% to 15%. TEG is usually used in remote areas where all other typical power sources are not available, such as deep space probes that cannot obtain solar energy but use the heat of plutonium particles.

The third factor is that for TEG to be usable, many parallels are required. Flexible and wearable TEGs usually exhibit the worst inefficiency characteristics, so hundreds of them need to be connected together. Trying to wear hundreds of TEGs to power a smartphone is not only impractical, but also unreliable.

Recognizing the challenges faced by TEG, researchers at Texas A&M University have developed a new energy conversion technology that may provide the energy needed for fever detection sensors.

The new concept uses carbon steel electrodes and solid polyelectrolytes made of polyaniline and polystyrene sulfonate. In short, when exposed to a temperature gradient, this combination of materials in an aqueous solution generates electricity. The temperature gradient causes an increase in overpotential corrosion in the carbon steel electrode, which promotes the flow of electrons in the generator.

So far, researchers have proved that the device can generate about 87mV per degree Celsius, which is far superior to most TEGs based on the Seebeck effect. In addition, the researchers connected the devices in series to generate enough voltage for the sensor circuit. 

The researchers’ main goal is to create a low-cost fever sensor that can help identify individuals who may be infected with the virus. Fever causes a sharp increase in body temperature, and this increase in temperature causes the worn TEG to produce more energy. This increased power can directly start the fever detector, or only provide operating power to obtain accurate temperature readings.

However, improving and reducing the size of this technology can be seen as a viable energy source for future wearable devices. Large devices (such as smartphones) are unlikely to be powered by TEG because they require a lot of power, but smart watches and other wearable medical sensors can indeed operate reliably on them.

In general, researchers have proved that wearable TEG has a lot of room for improvement, but in the current state, researchers are developing a fever-powered wearable device.

Recently, researchers have developed a generator that can use the heat generated by a fever to power basic wearable devices. What are the challenges of a typical thermoelectric generator, what did the researchers prove, and is it critical to power future medical devices?

Robin Mitchell is an electronic engineer who has been in the electronics industry since he was 13 years old. After completing his bachelor's degree at the University of Warwick, Robin entered the field of online content creation, developing articles, news and projects for professionals and makers alike. Currently, Robin runs MitchElectronics, a small electronics company that produces educational kits and resources.

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