Direct determination of the volumetric heat capacity of liquids using a MEMS sensor and efficient evaluation methods

In Beigelbeck et al [Meas. Sci. Technol. 22 105407, 2011], we presented a MEMS sensor containing two thin-film thermistors symmetrically arranged around a resistive heater and an associated measurement procedure to consecutively determine the thermal diffusivity and conductivity of liquids. In this contribution, we report an improved sensor design combined with two novel measurement methods featuring several distinctive advantages. First, the multi-bridge design enables up to four times faster acquisition of the required temperature-frequency response. Secondly, a newly developed AC-based measurement method facilitates direct determination of the volumetric heat capacity c_V of liquids which is an essential task in many condition monitoring applications. Thirdly, a novel impulse response approach allows rapid acquisition of c_V. Besides the sensor device, we present an analytical model for the basic sensing principle, both measurement methods, and sample measurements performed on selected liquids.