Group Members

• Published in the International Journal of Heat and Mass Transfer
• A novel thermal conductivity measurement method is introduced, studied through analytical and computational tools and its experimental implementation is discussed.
• The method is based on using the bolometric thermometry, which employs the material under test to be used as a thermometer through via temperature dependent electrical resistivity change.
• The method can extract thermal conductivity with thermal disturbances as small as 0.1 K to the sample.
• The method can be used to explore non-Fourier heat transport regimes.

We have developed a method for measuring heat flow at the nanoscale, a development that could advance our understanding in electronics, energy, and materials science.

We have developed a new technique for observing how heat travels through very small materials. Our approach, which we have named mechanical bolometric thermometry (MBT), provides a novel method for thermal conductivity measurements at the nanoscale. The method is based on our optical bolometric thermometry, but with more widespread applicability. Our findings, published in the International Journal of Heat and Mass Transfer, could be an important contribution to the direct measurement of thermal conductivity.

At the core of this study is the use of an atomic force microscope (AFM), a tool capable of imaging and manipulating matter at the atomic level. We have devised a way to use the AFM’s ultra-fine tip not just to see, but also to measure the heat of a material with high precision. By creating a thermal contact with the surface of a low-dimensional solid our AFM tip creates a tiny, localized hot spot. We then measure the resulting change in the material’s electrical resistance, a phenomenon known as the bolometric effect. This measurement provides us with a direct reading of the material’s thermal conductivity.

The implications of our work can be far-reaching. As electronic components continue to shrink, the challenge of dissipating the heat they generate becomes a primary design constraint. A better understanding of heat transport at the nanoscale is necessary for engineering more efficient and reliable devices. Our MBT method provides a new tool for this purpose, allowing us and other scientists to test and characterize the thermal properties of new materials with high accuracy.

Our study highlights the method’s capabilities, including the ability to measure temperature changes as small as 0.2 Kelvin with a spatial resolution of about 20 nanometers, representing an advance in thermometry. Furthermore, our technique is versatile, applicable to a wide range of materials and temperatures, from cryogenic levels to above room temperature. This versatility allows for the exploration of fundamental questions about heat flow in both conventional (Fourier) and exotic (non-Fourier) regimes.