We develop a temperature controllable microfluidic device for the accurate measurement of temperature dependent interfacial tensions between two immiscible liquids. A localized temperature control system is integrated with the microfluidic platform to maintain an accurate temperature inside the device. The temperature uniformity and sensitivity are verified by both simulation and experimental results. Temperature dependent interfacial tensions are measured dynamically and rapidly, relying on quantitative analysis of the deformation and retraction dynamics of droplets under extensional flow. Our microfluidic tensiometry offers the capability of measuring temperature dependent interfacial tensions with precise and systematic temperature control in the range of room temperature to 70 °C, which is valuable for studying transient interfacial dynamics, interfacial reactions, and the surfactant adsorption process.
We developed an integrated microfluidic platform for instantaneous flow and localized temperature control. The platform consisted of a flow-focusing region for sample delivery and a cross-junction region embedded with a microheater for cell trapping and localized temperature control by using an active feedback control system. We further used it to measure the membrane transport properties of Jurkat cells, including the osmotically inactive cell volume (V) and cell membrane permeabilities to water (L) and to cryoprotective agent (CPA) solutions (dimethyl sulfoxide (DMSO) in this study) (P) at various temperatures (room temperature, 30 °C, and 37 °C). Such characteristics of cells are of great importance in many applications, especially in optimal cryopreservation. With the results, the corresponding activation energy for water and CPA transport was calculated. The comparison of the results from the current study with reference data indicates that the developed platform is a reliable tool for temperature-dependent cell behavior study, which provides valuable tools for general cell manipulation applications with precise temperature control.
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