Characterization of Temperature Rise in Alternating Current Electrothermal Flow Using Thermoreflectance Method

Area of Science:

• Biomicrofluidics
• Electrokinetics
• Thermal Imaging

Background:

• Alternating current electrothermal flow (ACET) uses Joule heating for liquid transport in microchannels.
• High temperatures from Joule heating can degrade biological samples, limiting ACET applications.
• Accurate temperature monitoring is crucial for developing safe biomicrofluidic devices.

Purpose of the Study:

• To measure the temperature rise at the electrode/electrolyte interface during ACET flow.
• To validate an enhanced ACET theoretical model using experimental temperature data.
• To introduce a novel thermoreflectance imaging technique for electrode/electrolyte systems.

Main Methods:

• Utilized high-resolution, noninvasive thermoreflectance imaging to measure temperature.
• Applied ACET flow in microchannels with varying voltage levels.
• Compared experimental temperature data with predictions from an enhanced ACET theoretical model.

Main Results:

• Joule heating caused significant temperature increases, exceeding 50°C at 20 Vpp.
• The enhanced ACET theoretical model accurately predicted temperature rises, even at high voltages.
• Thermoreflectance imaging provided a reliable method for temperature measurement in electrode/electrolyte systems.

Conclusions:

• ACET can lead to excessive temperatures detrimental to biomolecules.
• The validated ACET model is essential for designing robust biomicrofluidic systems.
• This study establishes a new temperature measurement technique for electrode/electrolyte interfaces.