Original article: https://doi.org/10.3390/nano13111746
Over the past 20 years, the rapid development of micro- and nanomaterials—especially materials with tiny structures at the micro and nano scale—has led to growing interest in understanding how energy moves through them. This energy is mainly carried by electrons and phonons (tiny vibrations in materials), and their movement is strongly affected by how small and structured the material is.
Many advanced computer models have been created to study this, using methods like first-principles simulations, molecular dynamics, and lattice Boltzmann transport. At the same time, scientists have worked hard to invent new tools to measure heat-related properties—like thermal conductivity, diffusivity, and specific heat—at these very small scales.
Why is this difficult?
At the micro and nanoscale, materials are so small that it’s very hard to apply and measure heat accurately. You can’t just apply heat like in regular experiments. So, scientists developed special “transient” methods that quickly heat the material using electricity or laser light, then track how it reacts using sensitive electrical or optical tools.
Some of these new techniques include:
- Transient electro-thermal (TET)
- Transient photo-electro-thermal (TPET)
- Pulsed laser-assisted thermal relaxation (PLTR)
- Time-domain and frequency-resolved Raman techniques
These allow fast and precise measurement of heat behavior in extremely thin materials—even those just a few atoms thick.
What’s in this Special Issue?
This issue includes several important reviews and research articles on micro/nanoscale energy transport:
- Lin et al. reviewed the TET method, especially a version called differential TET, which helps measure heat properties in ultra-thin films.
- Kalantari and Zhang gave a broad overview of energy transport in 2D materials, including simulation and experiment-based methods.
- Dai and Wang, Liu et al., and Mohammad and Xian contributed experimental insights into energy transport studies.
- Zhou et al. explained how photothermal techniques can measure thermal conductivity and interface resistance in coatings, offering both theory and practical examples.
Highlighted Research Reports:
- Xu et al. used TET to study how heat moves through corn leaves and special polyethylene fibers during rapid heating—pushing the technique’s limits.
- Liu et al. investigated how graphene’s thermal conductivity changes with temperature—challenging due to material mismatch with its base layer.
- Wang et al. studied how MoS₂-carbon nanotube materials respond to heat, and Lin et al. explored how electrical current changes heat transport in carbon nanotubes.
- Deng et al. looked at energy transport during laser-based coating of corrosion-resistant NiTi materials.
- Nunes et al. analyzed how electrical charges move in energy-storage devices like double-layer capacitors, which is key to designing better energy systems.
Final Thoughts:
Energy transport at the micro and nanoscale remains a very active and exciting research field. Scientists are currently exploring:
- How phonons behave in tiny materials,
- How to design materials that either enhance or block heat movement,
- And how to create new tools for studying these effects in difficult conditions.
This work is critical for advancing technologies in electronics, energy, and materials science.