Thermodynamics of small systems by nanocalorimetry: from physical to biological nano-objects

TL;DR

This paper reviews advances in ac nanocalorimetry for measuring heat capacities of tiny systems, including superconductors, nanomagnets, polymers, proteins, and living cells, highlighting new phase transitions and out-of-equilibrium measurements.

Contribution

It introduces novel nanocalorimetry sensors and techniques for studying very small physical and biological systems across a wide temperature range.

Findings

Detection of new phase transitions in nanoscale superconductors

Development of sensors for biological and polymer systems

Ability to measure systems out of equilibrium

Abstract

Membrane based nanocalorimeters have been developed for ac calorimetry experiments. It has allowed highly sensitive measurements of heat capacity from solid state physics to complex systems like polymers and proteins. In this article we review what has been developed in ac calorimetry toward the measurement of very small systems. Firstly, at low temperature ac calorimetry using silicon membrane permits the measurement of superconducting sample having geometry down to the nanometer scale. New phase transitions have been found in these nanosystems illustrated by heat capacity jumps versus the applied magnetic field. Secondly, a sensor based on ultra-thin polymer membrane will be presented. It has been devoted to thermal measurements of nanomagnetic systems at intermediate temperature (20K to 300K). Thirdly, three specific polyimide membrane based sensors have been designed for room temperature measurements. One is devoted to phase transitions detection in polymer, the second one to protein folding/unfolding studies and the third one will be used for the study of heat release in living cells. The possibility of measuring systems out of equilibrium will be emphasized.