Thermophoresis in Aqueous Systems

01 — Fundamental Mechanisms

Colloid Thermophoresis in the Dilute Electrolyte Concentration Regime: From Theory to Experiment

Soft Matter, 2023 · DOI

We developed a thermofluidic platform with femtonewton sensitivity to probe colloid–solvent interactions and investigate the temperature and size dependencies of silica thermophoresis in dilute electrolyte solutions. By combining experiments with a theoretical model based on the Fokker–Planck equation that incorporates electrostatic and short-range hydrogen-bonding interactions, we revealed how the interplay between these interactions governs thermophoretic behavior at the molecular level.

02 — Theoretical Development

A Mode-Coupling Model of Colloid Thermophoresis in Aqueous Systems: Temperature and Size Dependencies of the Soret Coefficient

Nano Letters, 2024 · DOI

We developed a holistic model to reveal the multi-scale coupling mechanisms underlying colloid thermophoresis in aqueous systems, where the coupling is governed by Onsager’s reciprocal relations. The model shows that the temperature dependence of the Soret coefficient stems from competition between long-range bulk and short-range interfacial effects. Its size dependence relies on the volume–surface area scaling of short-range interactions and depends on the particle surface chemistry.

03 — Surfactant-Mediated Interfacial Modulation

Colloid Thermophoresis in Surfactant Solutions: Probing Colloid–Solvent Interactions Through Microscale Experiments

The Journal of Chemical Physics, 2024 · DOI

We investigated the thermophoretic response of silica microspheres in nonionic and ionic surfactant solutions using capillary electrophoresis–thermophoresis (CET). Combining experiments with model calculations, we identified distinct charging mechanisms at the silica–water interface and showed how temperature, surfactant type, and concentration influence electrostatic and hydration entropy interactions, thereby modulating colloid thermophoresis.

04 — Translational Application

Colloid-Based Thermophoretic Technology for PFAS Detection

Co-Inventor · U.S. Provisional Patent, 2026 · Technology Transfer via Innovate Calgary

Building on our fundamental studies of colloid thermophoresis, we developed a label-free thermophoretic technology for PFAS detection. The technology measures changes in particle motion induced by PFAS adsorption under a controlled temperature gradient, with shifts in the Soret coefficient serving as the detection signal.