For more than a decade, the IES laboratory has been working in collaboration with the CEA on the development of acoustic instrumentation in the nuclear field. Within the framework of this collaboration, the IES acoustic team is developing a miniaturized gas composition sensor for in situ measurements of gas composition in a fuel rod. The first experimental evidence of an acoustic measurement to perform a gas composition measurement date back to 2010 with the REMORA 3 experiment, which measured the release of fission gas from fissionable fuel. The first experimental evidence of an acoustic measurement to perform a gas composition measurement date back to 2010 with the REMORA 3 experiment, which measured the release of fission gas from fissionable fuel. This experiment was carried out in the OSIRIS reactor located at CEA Saclay in France. The installation allowed the devices to be tested under irradiation at 150°C [1,2], which corresponded to the maximum operating Curie temperature allowed by PZT element. But the new sensors presented in this paper will be able to operate up to 300 degrees, this performance is possible by the utilization of a modified Bismuth Titanate piezoelectric (NBT). The integration of the material is done by screen printing process on alumina substrate [3,4]. The fabrication process and first characterization have been presented in the previous version of ANIMMA 2021 [5]. In this paper, we will focus on the performances of this kind of sensor. In our laboratory, we have conceived two experimental benches, the first one permitted to test the sensor in different mixes of different gas such as helium and xenon. And the second bench, measure the variation of impedance of our piezoelectric elements under temperature. This experiment will allow us to replicate the condition of temperature and pressure decorrelated, and see if the sensor can operate a gas composition measurement in JHR thermodynamic condition. These experiments will allow us to validate the concept and design of this device before final validation tests under irradiation in 2023 or 2024.