Simultaneous thermal conductivity and diffusivity sensing in liquids using a micromachined device

Due to unique features like small thermal masses and reduced conductivities, membrane-based micromachined thermal sensors offer features superior to those provided by comparable macroscopic measurement setups. In this contribution a micromachined device is applied to characterize the thermal transport properties of various liquids. By means of sinusoidal excitation of a heater structure placed on a membrane and recording the resulting temperature at a specified distance using integrated germanium thermistors, the liquid's thermal parameters can be determined. A simple two-dimensional (2D) analytical model allows to interpret the amplitude and the phase of the measured sinusoidal temperature variation yielding both, the thermal conductivity and the diffusivity of the liquid. (c) 2005 Elsevier B.V. All rights reserved.