A research team affiliated with UNIST has unveiled a technological advancement that allows body heat to generate electricity sufficient to power electronic devices. This innovation paves the way for the commercialization of battery-free wearable gadgets and Internet of Things (IoT) sensors that operate solely on heat generated by the human body.

Led by Professor Sung-Yeon Jang from the School of Energy and Chemical Engineering at UNIST, the research team developed the world’s first high-performance n-type solid-state thermogalvanic cell capable of powering actual electronic devices. The paper is published in the journal Energy & Environmental Science.

Thermogalvanic cells are compact generators that convert temperature differences—such as the human body temperature (~36°C) versus surrounding air (20–25°C)—into electrical energy. However, due to the minimal temperature gradient, previous systems struggled to produce enough power to operate real-world electronics.

The newly developed solid-state device overcomes this challenge by delivering sufficient voltage and current to power practical devices. While solid-state designs typically offer advantages such as safety from leakage, ion mobility issues within the electrolyte have historically limited their current output. The research team engineered an electrolyte that facilitates efficient ion transport, and further, the thermally driven ion diffusion enhances overall output voltage.

By connecting 100 of these cells in series—similar to building with LEGO blocks—approximately 1.5V can be generated from body heat, comparable to standard AA batteries. Connecting 16 such series-connected modules enables the activation of devices like LED lights, electronic clocks, and temperature/humidity sensors.

Notably, the cell’s Seebeck coefficient (voltage change per temperature difference) is –40.05 mV/K, representing up to a fivefold increase over conventional n-type cells. The device also demonstrated excellent durability, maintaining consistent performance after 50 charge-discharge cycles.

The core of this solid-state cell comprises a conductive polymer, PEDOT:PSS, and a redox couple of Fe(ClO₄)₂/3. Electrostatic interactions between the negatively charged sulfonate groups (–SO₃⁻) of the polymer and the Fe²⁺/Fe³⁺ ions establish a stable structure, while perchlorate ions (ClO₄⁻) are free to move, facilitating ion diffusion and thermodiffusion effects that boost power output.

Professor Jang stated, “This research marks a new milestone in low-temperature waste heat energy harvesting and flexible energy conversion devices. It has the potential to serve as a self-powered system for wearable electronics and autonomous IoT devices driven solely by body heat.”

The National Institute for Materials Science (NIMS), in collaboration with Seikei University, has successfully enhanced the power output of lithium-air batteries, which are attracting attention as next-generation batteries. By developing a highly porous electrode made of carbon nanotubes, the team achieved a tenfold increase in output current. The lithium-air battery developed in this study not only has extremely high energy density compared to lithium-ion batteries but also significantly improved power performance.

As a result, it is now able to supply the power required for hovering small drones, making significant improvements in flight duration feasible. These results were published online in the Journal of Power Sources on February 9, 2025.

Lithium-air batteries (LABs) are rechargeable batteries that operate through discharge and charge reactions using lithium and oxygen. They are attracting attention as an energy storage technology capable of achieving significantly lighter weight and larger capacity than conventional lithium-ion batteries, with a potential energy density 5 to 10 times higher. However, lithium-air batteries have extremely slow reaction kinetics, resulting in only very weak output current. To make use of the large amount of energy stored in lithium-air batteries, a fundamental improvement in their power output has been required.

The research team developed a highly porous carbon nanotube air electrode that significantly improved oxygen accessibility. When combined with a low-viscosity amide-based electrolyte, the new design enabled a tenfold increase in current density. The resulting battery achieved a specific power density sufficient to support hovering in lightweight drones.

Based on these results, the team aims to scale up lithium-air battery cells, with the goal of developing ultra-lightweight and high-capacity batteries that can be used as power sources for small drones and microrobots.

Elon Musk’s SpaceX has reached a deal worth about $17 billion with EchoStar for spectrum licenses that it will use to beef up its Starlink satellite network.

The deal for EchoStar’s AWS-4 and H-block spectrum licenses includes up to $8.5 billion in cash and up to $8.5 billion in SpaceX stock. SpaceX will make approximately $2 billion in cash interest payments on EchoStar debt through November 2027.

SpaceX and EchoStar will enter into a long-term commercial agreement which will allow EchoStar’s Boost Mobile subscribers to access SpaceX’s next generation Starlink Direct to Cell service.

Shares of EchoStar surged 19% before the market opened Monday.

Last month AT&T said that it will spend $23 billion to acquire wireless spectrum licenses from EchoStar, a significant expansion of its low- and mid-band coverage networks.

EchoStar said that it anticipates that the AT&T deal and the SpaceX transaction will resolve recent inquiries from the Federal Communications Commission about the rollout of 5G technology in the U.S. The FCC had been calling for hearings on whether Echostar was properly using the spectrum that it is now selling, and its efforts to make 5G more available to communities.

EchoStar said Monday that it will use the proceeds from the sale partly to pay down debt. Current operations of Dish TV, Sling and Hughes will not be impacted, the company said.

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