Localized Joule heating produced by ion current focusing through micron-size holes

TL;DR

This paper demonstrates that focusing ionic currents through micron-sized holes can generate significant localized Joule heating, enabling precise thermal control and measurement of DNA melting profiles.

Contribution

It experimentally shows localized Joule heating via ion current focusing and validates results with numerical modeling, suggesting potential for sub-micron pore applications.

Findings

Localized temperature increases up to 100°C observed.

Good agreement between experiments and finite element simulations.

Thermal gradients used to measure DNA melting profiles.

Abstract

We provide an experimental demonstration that the focusing of ionic currents in a micron size hole connecting two chambers can produce local temperature increases of up to $100^\circ$ C with gradients as large as $1^\circ$ K$\mu m^{-1}$. We find a good agreement between the measured temperature profiles and a finite elements-based numerical calculation. We show how the thermal gradients can be used to measure the full melting profile of DNA duplexes within a region of 40 $\mu$m. The possibility to produce even larger gradients using sub-micron pores is discussed.