PORTEFEUILLE

The microelectronic industry presents a strong interest in powering microelectronic autonomous mobile devices by harvesting energy from the local environment. One of available technology is to convert waste heat into electricity by thermoelectric conversion. This conversion process is purely electronic, without any moving part, and therefore has quasi-infinite lifetime. This permanent powering solution presents a promising alternative to lifetime-limited batteries.

Thermoelectric generators currently available are based on bulk Bismuth chalcogenide compounds, well known for being the most efficient thermoelectric materials at room temperature. Nevertheless these generators are too large for microelectronic devices, and too expensive due to high production costs, making them unsuitable for large scaleintegration in microelectronic devices.

To overcome this drawback, we propose a multi-disciplinary approach combining Physics, Thermoelectrics, Electrochemistry, nano/micro-techniques and Microelectronics, to develop of a cost-effective nanotechnology to synthesize a novel ultra-thin flexible nanostructured thermoelectric device, able to feed low-power electronics. The controlled composition, microstructure, shape and dimensions gives the ability to tailor electrical and thermal properties of nanomaterials, providing a unique opportunity of a breakthrough in terms of thermoelectric efficiency.
Taking advantage of the knowledge acquired during the proof-of-concept stage, performed previously, the present project aims at building a functional demonstrator of a thermoelectric nanostructured device able to fulfill the benchmarking of the Swiss industry: provide a flexible cost-effective thermoelectric generator for wasted heat energy harvesting, to power autonomous microelectronic devices.

Watchmakers and Sensor industries show interest in our technology concept, and wait for a functional demonstrator to go further in a technology transfer process.

The use of nanotechnology to tailor electrical and thermal properties of energy conversion modules and restrain fabrication steps for lower production costs. The very low thickness of the energy conversion modules opens to new fields of applications.

Thermoelectric nanocomposites
Two kinds of thin-film thermoelectric nanocomposites have been synthesized. Unfortunately, despite numerous efforts one kind of nanocomposite still shows properties unsuitable for thermoelectric applications. The reasons of a such surprising behavior have not been identified as far, and are still under investigation. This unexpected problem prevents the complete fulfilment of the project.

Nanostructured thermoelectric modules
Despite the poor thermoelectric properties of the nanocomposites, we successfully fabricated thin-film nanostructured thermoelectric modules. We developed for this stage a new fabrication process which allows the fabrication of nanostructured in one single step, avoiding then the numerous and costly lithography steps conventionally used in nanotechnology processes. Other steps are close to standards of the PCB makers. This is the most promising results of the project.

Test bench
Since our nanostructured thermoelectric modules are films five to ten times thinner than a human hair, measuring their electrical and thermal properties needed dedicated tools. We successfully developed a test bench able to precisely determine the heat-to-electricity conversion rate of our devices. This stage feeds a valuable know-how on measuring ultra-thin structures and devices.

Technology demonstrator
The overall goal of the project is to fabricate a technology demonstrator for industry and general public. This has been successfully performed: a device has been designed and fabricated that convert the heat of hot water into electricity, to send by Bluetooth communication some data about the so-produced electrical power. This device is now waiting for effective thin-film nanostructured thermoelectric modules.

In conclusion, the synthesis of suitable thin-film thermoelectric nanocomposites is a break to complete this project. A breakthrough will then allow to set a functional demonstrator able to show the potential of this technology to power autonomous microelectronic devices.

None so far

None so far