Researchers developing a fever-powered wearable device

Recently, researchers have developed an electric generator that can utilise the heat from fever to power basic wearable devices. What challenges do typical thermoelectric generators present, what did the researchers demonstrate, and could it be vital to powering future medical devices?

What challenges do traditional thermoelectric generators present?

Thermoelectric generators often make the news, with researchers attempting to miniaturise them, hoping they can be made wearable. If successful, a wearable TEG could power mobile devices indefinitely using only body heat as the energy source. This would remove the need for charging stations for devices, power smart medical devices, and even provide medical implants.

However, the truth about TEGs is that they are extremely inefficient and produce very little power. The reason for TEGs inability to be effective stems from multiple factors, and these factors essential prove that humans are very poor sources of energy.

The first factor is that TEGs require temperature gradients to produce electricity, and the temperature difference between human skin and room temperature is hardly vast (10°C to 15°C at most). This temperature gradient is made worse in hot countries where the ambient temperature can be cooler than skin. 

The second factor is that TEGs are naturally inefficient devices; typical TEGs have efficiencies of around 5% to 15%. TEGs are generally used in remote locations where all other typical power sources are unavailable such as deep space probes that cannot access solar energy and instead use heat from plutonium pellets.

The third factor is that for TEGs to be useable, many in parallel are required. TEGs that are flexible and wearable often exhibit the worst qualities of inefficiency and thus require many hundreds connected together. Trying to wear several hundred TEGs just to power a smartphone would not only be impractical but unreliable.

Researchers develop new thermo-battery technology

Recognising the challenges faced by TEGs, researchers from Texas A&M University have developed a new energy conversion technology that could potentially provide the power needed for fever-detecting sensors.

The new concept uses carbon steel electrodes and a solid-state poly-electrolyte made of polyaniline and polystyrene sulfonate. Simply put, this combination of materials in a water solution will generate electricity when exposed to a temperature gradient. The temperature gradient causes the overpotential corrosion to increase in the carbon steel electrode, facilitating electron flow in the generator.

So far, the researchers have demonstrated that the device can produce approximately 87mV per degree Celsius which is far better than most TEGs based on the Seebeck effect. Furthermore, the researchers connected devices in series to produce a few more than enough volts for sensor circuitry. 

Could the new device power future wearable medical devices?

The main goal for the researchers was to create a low-cost fever sensor that could help identify individuals who may have a viral infection. A fever increases the body temperature dramatically, and this temperature rise would result in more power being generated by a worn TEG. This increased power could either directly startup the fever detector or just provide power to operate, whereby it would take accurate temperature readings.

However, refining and reducing the size of the technology could see it as a viable energy source for wearable devices in the future. Large devices such as smartphones will unlikely be powered by TEGs due to their substantial power requirements, but smartwatches and other wearable medical sensors could indeed operate reliably on them.

Overall, the researchers have demonstrated that wearable TEGs have plenty of room for improvement, but in their current state are Researchers developing a fever-powered wearable device.

Recently, researchers have developed an electric generator that can utilise the heat from fever to power basic wearable devices. What challenges do typical thermoelectric generators present, what did the researchers demonstrate, and could it be vital to powering future medical devices?