Technology to harvest the energy of devices and convert wasted heat The trend in microelectronics to put more computational power in smaller packages pushes the threshold of heat management capabilities. An EU initiative developed novel thermoelectric modules to harvest waste heat and use it to support chip functions. Industrial Technologies Energy © f-64 Photo Office/amanaimagesRF, Thinkstock So many transistors in such a small space dissipate too much heat, impeding chip function. This makes it increasingly important to find ways to control heat flow, particularly through crystalline materials, such as silicon, that form the foundation of most devices. Thermal or vibrational energy from atoms oscillating in a crystal lattice is embodied in phonons, the particle equivalent of the mechanical wave that is created. Controlling phonons thus enables control of thermal transport, and this is what the EU-funded MERGING (Membrane-based phononic engineering for energy harvesting) project set out to do. The focus was on silicon-compatible materials and technologies. Project partners developed a thermoelectric generator (TEG) module to convert waste heat to electricity, offsetting the power requirements of increasingly power-hungry microelectronics while minimising heat build-up. The TEG includes a tailor-made power circuit to boost low voltage generation that was successfully tested in the lab. Project partners devised and applied advanced techniques to measure thermal properties in membranes and thin films. They performed an extensive theoretical examination of thermal energy transport. A new neural network model was introduced that reproduces the vibrational properties of nano-structured germanium manganese and supported development work. The MERGING team also fabricated silicon and germanium membranes with phononic crystals, and demonstrated the effect of those crystals on phonon dispersion and the thermal properties of the membranes. Researchers presented the results at 90 international conferences, talks and poster presentations. In addition, they published 19 peer-reviewed articles. MERGING will have important impact on energy harvesting and energy control in information and communication technologies. Optimisation of the lab-scale technology using autonomous and embedded sensors could eventually improve the situation for other sectors such as health and the environment. The possibility of powering low-energy devices such as the Internet of Things is closer to becoming reality. Keywords Waste heat, phonons, MERGING, energy harvesting, thermoelectric generator module
