Thermal Characterization of a Thin Film Heater on Glass Substrate for Lab-on-Chip Applications

This paper presents for the first time an accurate thermal characterization of thin film heaters manufactured on glass substrates. The characterization has been performed on Cr/Al/Cr meandered heaters. Techniques commonly adopted for measuring the temperature coefficient of resistance, the thermal resistance and thermal capacitance in the case of Si-based microheaters have been conveniently modified to take into account the fundamentally different thermal parameters of a heater manufactured on glass. In order to reduce power consumption, 250 μm wide trenches were manufactured on the back side of the heaters, obtaining an increase of the thermal resistance of about 50% when the glass is in good thermal contact with a heat sink. The measured values of thermal resistance and time constants on a heat sink and in air have been justified with simple physical considerations. Guidelines are also given for a further increase of the thermal resistance of the thin film heaters.