Micro-Fluidic Lab-on-Chip Project

Snow

AC electrothermal flow (ACET) induced by Joule heating is utilized to transport biologically relevant liquids in microchannels using simple electrode designs. However Joule heating may cause significant temperature rises, which can degrade biological species, and hence, ACET may become impractical for biomicrofluidic sensors and other possible applications. In this study, the temperature rise at the electrode\electrolyte interface during ACET flow is measured using a highresolution, non-invasive, thermoreflectance imaging method, which is generally utilized in microelectronics thermal imaging applications. The experimental findings reveal that Joule heating could result in an excessive temperature rise, exceeding 50°C at higher voltage levels (20 Vpp). The measured data are compared with the results of the enhanced ACET theoretical model, which predicts the temperature rise accurately, even at high levels of applied voltages. Overall, our study provides a temperature measurement technique, which is used for the first time for electrode/electrolyte systems. The reported results are critical in designing biomicrofluidic systems with significant energy dissipation in conductive fluids.

Flowers in Chania
Thermoreflectance thermal imaging setup and the sample structures b) for calibration and c) for activation. The microfluidic channel is assembled in activation only. In calibration, the temperature rise is applied through the thermal chuck.
Mountains
a) Numerical simulation domain showing the three electrodes and the microfluidic medium. b) Joule heating induced temperature rise as obtained from the numerical results. c) Close up of the temperature rise field around the three electrodes.
Mountains
a) Measurement results showing the temperature traces across the three electrodes at dfferent voltage levels. b) experimental and numerical results showing average temperature rise on the side and middle electrodes as function of applied peak to peak voltage. c) Thermal map obtained at 20V peak to peak. d) Flow field between the electrodes at 5 MHz and 20 Vpp.
Steady State thermal respone of electrodes at 5X. Vpp between 0 and 20 V.
Steady State thermal respone of center electrode at 100X.

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Microfluidics Lab-on Chip

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Measuring and modeling the self-heating of electrodes under AC Electrothermal microfluidic manipulation.