A micro differential thermal analysis (μDTA) system

This paper reports on a microsystem for differential thermal analysis (DTA) useful for the thermal characterization of phase transitions in small samples. The system consists of micromachined hotplates made of silicon oxide and nitride with integrated heaters and thermistors. The symmetric layout of the hotplate guarantees a homogeneous temperature distribution across the heated part of the membrane with deviations |ΔT|≤2 K at temperatures up to 560 K. In experiment and modelling different heating modes, such as rectangular or triangular pulses or sinusoidal thermal excitation at frequencies f up to 10 Hz, are applied. The principle of differential thermal analysis (DTA) is demonstrated through the extraction of melting points T_m of various materials. In case of benzophenone with an estimated sample mass of 50 μg, T_m is determined with an accuracy better than 2 K with respect to the literature value.