Introduction: Nano and Energy

Welcome! Our research group works on fundamental aspects of thermal sciences and energy conversion. We seek challenges and opportunities by going to extremes. Our work sometimes has a strong eye on an application (“Pasteur’s quadrant”), while at other times is driven more by fundamental curiosity (Bohr’s quadrant). In all cases we aim at excellence, innovation, impact, and lasting significance.

We do both experiments and modeling, and some of our best work comes at their intersection. We enjoy collaboration: within the lab group, across Berkeley and LBNL, and around the world.

Fundamentals

We love a challenge and the chance to explore untouched regimes. Here are a few examples of the types of problems that get our juices flowing -- past, present, and future:

• What if we could measure the temperature of a single atom? In highly driven systems, can we think of temperature as being directional, T(θ,ϕ)? What does temperature even mean in such extreme conditions?
• How can we understand the thermal properties of materials that are only one atom thick? How to measure them, how to model them, how to develop intuition?
• What is microscale thermal transport like inside biological tissues, or even within a single cell?
• How can we develop highly-effective thermal switches and diodes? What disruptive new applications would be enabled? Could we double the thermal performance of electric car batteries and building envelopes?
• How does thermal physics change at extreme temperatures, from 1 K to 3,000 K?
• How can we formulate new dimensionless groups that incorporate cost?
• How can we understand direction-dependent (anisotropic) transport, and take advantage of it for extreme properties and applications? Can we access coherent phenomena in thermal transport?
• What if we could perform measurements with a million heaters and thermometers simultaneously, rather than only one or two? How to handle this tremendous data stream? How to exploit it for high-throughput materials development? For thermal tomography?

Applications

We are interested in any application in which our work can make an impact. Some examples:

• The global energy/climate challenge is profound and much of our work bears on this in one way or another, from understanding energy conversion and thermal transport fundamentals down to the atomic scale, to developing new concepts for how thermal switches and diodes can be used for thermal management of batteries and buildings.
• From transistors to memory, the relentless advances in microelectronics are another major driver. With device length scales now ~10 nm and below, the thermal transport problems involve tremendous heat fluxes and the challenges emphasize interfaces, ballistic rather than diffusive heat transfer, and the potential for coherence phenomena, all of which we work on both theoretically and experimentally. The recent push towards quantum information science broadens these thermal challenges into even more exotic materials and regimes.
• Biological applications are also exciting, from therapeutic treatments to tissue preservation. Working with collaborators we are interested in challenging measurements, from ex-vivo samples to living biological systems.
• We also have advised and consulted on a range of other fundamental thermal science questions with diverse applications including wine storage, football air pressure, power electronics, and innovative x-ray sources.