First steps to develop a sensor for a Tian–Calvet calorimeter with increased sensitivity

Abstract

Abstract. Initial steps to apply a ceramic multi-layer technique to build a new sensor for a Tian-Calvet calorimeter are presented in this contribution. The new sensor has a stacked design of ceramic sensor discs and insulating rings. The development was finite-element method (FEM) supported to design the sensor disc. In the next step, the function of the sensor disc was proven up to a temperature of 600 • C. Finally, the entire stack was tested at room temperature, delivering a resolution of 5 µW and a maximum sensitivity of 8.5 µV mW −1 . The time constant is strongly dependent on the mass of the cuvette. We show that the time constant of the sensor can be more exactly characterized when using a novel low temperature co-fired ceramic (LTCC) cuvette with a low mass and an integrated heater. Then, the time constant can be reduced to T 1/e = 118 s. The new sensor shows similar specifications as commercial devices and presents a good starting point for future high temperature applications.

Optimization of a sensor for a Tian–Calvet calorimeter with LTCC-based sensor discs

“…It is therefore reasonable to limit the sensor to 8 discs to reduce production cost. As a result of these optimization processes, the sensitivity of the sensor is increased by a factor of about 3 compared to the original sensor as reported in Schubert et al (2016) and as can be seen when comparing the sensitivities in Fig. 4e ("original 34" vs. the other curves).…”

“…For calibration and test runs, the previously described metal and LTCC cuvettes were used (Schubert et al, 2016). For calibration, the internal heaters of the cuvettes were heated by a controlled current to release the defined power P .…”

“…Figure 3a shows the original sensor disc with 34 thermocouples. It had been used for the proof of concept (Schubert et al, 2016) and has now been used to validate the model. The influence of an increased number of thermocouples was investigated with a design consisting of 67 thermocouples (Fig.…”

“…A calibration run then delivers a function between the measured temperature difference and the heat flow (Sarge et al, 1994). In our previous work, we have demonstrated the feasibility of a sensor for a TianCalvet calorimeter based on low temperature co-fired ceramics (LTCC) technology (Schubert et al, 2016). The base material for this process are green (unfired) glass-ceramics sheets that can be handled like plastic foils.…”

“…In our previous work, the sensitivity of the sensor was measured at room temperature using a heated cuvette that distributes the heat for calibration evenly amongst the sensor. To fully understand the scope of this work, the reader is referred to the previous paper by Schubert et al (2016).…”