Researchers from the Ulsan National Institute of Science and Technology (UNIST) have developed an ink to 3D write microthermoelectric generators. These generators show a promise to be small and customizable enough to fit into wearable electronics, opening up the possibility that they may, one day, replace conventional batteries.
Thermoelectric materials create energy by taking high heat rapidly to a cooler area. This technology has the potential to become a viable and inexpensive source of renewable energy by converting wasted heat into usable power.
Energy-harvesting thermoelectric modules could potentially be integrated into the systems they serve; however, conventional manufacturing practices are complex, costly, and have only been able to produce two dimensional structures, limiting efficiency and widespread potential. UNIST scientists were able to develop an ink formula for the microscale 3D printing of thermoelectric parts. Researchers looked at ink colloidal rheology, that is the size and pattern of charged particles. What they determined was that particles that were smaller and bunched narrower produced a higher viscosity. By controlling surface oxidation, the team could enhance rheological properties.
This led the researchers to develop an ink that printed a generator with tiny, sturdy columns (1.4mm tall, 0.55mm diameter) onto a silicon chip. When the generator was heated from one side and cooled from the other, it produced 479W of power, enough energy for a network of small wireless sensors. The ink is a (Vi,Sb)2(Te,Se)3-based particle material engineered for high viscoelasticitty, without the need for organic binders, and that can be directly written into complex architectures.
Schematic for direct ink writing of 3D printed thermoelectric architectures. Image courtesy of Nature Electronics.
“If we use 3D printing technology in the production of thermoelectric materials, we will be able to overcome limits of conventional materials,” said Professor Han Gi Chae of UNIST’s Department of Materials Science and Engineering. “The new technology for providing viscoelastic characteristics to 3D printed materials will be used in various other sectors.”
Such technology could be used anywhere there is rapid generation and cooling of heat, such as wind turbines, factories, or even the human body. The same scientific team tangentially developed 3D printed power-generating tubes that can convert wasted heat from industrial or automotive exhaust systems. They used an extrusion-based process to print a material made of lead (Pb) and tellurium (Te) into tube-like shapes.
Caption: “Figure 1. 3D printing of power-generating TE tube. a) Scheme showing the power-generating TE tube made of the 3D-printed p-type and n-type PbTe tubes at the front view. b) Photograph showing the components for the module assembly. c) Photograph of the fabricated power-generating TE tube chipping unipair of p-type and n-type PbTe legs and schematic model of a power-generating tube chipping ten pairs of TE legs assembled from the fabricated unit module.” Image courtesy of Nature Electronics.
Professor Jae Sung of UNIST’s Department of Materials Science and Engineering says, “Through this research, we will be able to effectively convert heat generated by factory chimneys, the most common type of waste heat source, into electricity.”