A future where smartwatches and fitness bands require no charging is on the horizon, thanks to advancements in flexible thermoelectric films. Researchers at Queensland University of Technology have developed a highly efficient film that generates energy from body heat. This innovation allows devices to remain powered continuously, overcoming previous limitations in flexibility and efficiency. The new technology could lead to smartwatches that never need recharging, revolutionizing user convenience and device functionality.
The Future of Smartwatches: Never Charge Again?
Imagine a world where your smartwatch or fitness bracelet never needs recharging. This innovative breakthrough is paving the way for a future without the hassle of chargers.
Smartwatches and connected bracelets offer a plethora of features, from tracking fitness performance to managing notifications and calls. However, these conveniences come with the constant need to recharge the devices, which can quickly become a daily chore. The ultimate goal is to create a device that generates its own energy while simultaneously consuming it.
Harnessing Heat for Continuous Energy
When considering energy sources for such devices, heat emerges as the most viable option. We naturally produce heat, leading to the concept of batteries that harness our own body emissions. However, the thought of carrying a thermal generator along with a smartwatch isn’t appealing. Fortunately, a solution already exists in the form of flexible thermoelectric films, known as F-TEDs.
These ultra-thin films, measuring less than a human hair, have the potential to provide continuous power to a smartwatch. While F-TEDs have been around, the challenge has always been their flexibility and efficiency. Researchers at the Queensland University of Technology, led by Professor Zhi-Gang Chen, have developed a new thermoelectric film that addresses these issues effectively.
Chen emphasizes the film’s capabilities: “The energy generated by the [F-TED] we created would not be enough to charge a smartphone but should be sufficient to power a smartwatch.” This means envisioning a scenario where an Apple or Pixel Watch remains charged at all times, although some industrial engineering and optimization would be necessary to make it a reality.
A prototype tested in 2021 demonstrated that a bracelet could generate 35 microwatts of energy per cm² simply from being worn. The latest film is now 34 times more efficient at room temperature, setting a record in the field. So, what has changed over the past three years?
The answer lies in a streamlined manufacturing process designed for mass production. Chen’s team utilizes bismuth telluride, a common and accessible semiconductor, employing screen printing techniques similar to those used in creating printed circuits.
By the end of production, they create a flexible thermoelectric film measuring just 1 micron thick. For context, a single human hair has an average diameter of 50 to 70 microns.
An A4 sheet cut from this film can generate 1.2 milliwatts per cm² at an ambient temperature of around 16° Celsius—adequate power for a smartwatch or comparable device.
Unlike previous F-TEDs, this new version incorporates tellurium nanotubes, enhancing its density and durability. Remarkably, even after twisting it a thousand times, the film loses only 2% of its energy efficiency. Researchers anticipate it could endure anywhere from 10,000 to even 1 million twists without significant degradation.
Additionally, this film can be cooled using a minimal electric current, hinting at the possibility of integrating it into silicon chips, such as those found in smartphone processors. However, achieving this would require a complete redesign of their production processes, necessitating collaboration across multiple scientific and engineering disciplines. While it is a challenging task, it remains a feasible goal for the future.