On the importance of telemetric temperature sensor location during intraperitoneal implantation in rats.

This study aims to assess the thermal homogeneity of the intraperitoneal (IP) cavity and the relevance of using a fixed telemetric temperature sensor at a given location in studying rodents. Ten rats were intraperitoneally implanted with three Jonah® capsules each; after assessing the accuracy and reliability of the sensors. Two capsules were attached, one to the right iliac fossa (RIF) and the other to the left hypochondrium (LH), and another was placed between the intestines but not attached (Free). In the ex vivo condition, the differences between sensors and reference values remained in the range of ±0.1. In the in vivo condition, each sensor enabled the observation of temperature patterns. However, sensor location affected mean and median temperature values while the rats were moving freely. Indeed, temperature data collected in the LH were 0.1 significantly higher than those collected in the RIF and temperature data collected in the LH were 0.11 significantly higher than those collected with the Free capsules. In in vivo conditions, intra-sensor variability of temperature data was not affected by sensor location. Taking into account sensor accuracy, similar intra-sensor variability, and mean differences observed between the three locations, the impact of sensor location within the IP cavity could be considered negligible. In in vivo conditions, temperature differences between locations regularly exceeded ±0.2 and reached up to 2.5. These extreme values could be explained by behavioral factors such as food or water intake. Finally, considering the good thermal homogeneity of the IP cavity and possible adverse consequences of sensor attachment, it seems better to let sensors range free within the cavity.

Calibration and performance assessment of a temperature sensor prototype using a 1-point calibration procedure.

This study aims to assess the relevance of 1-point calibration procedure, within the framework of the development of a new telemetric temperature sensor. The criteria used for performance assessment were the level of accuracy, and the time of inertia of the temperature sensor prototype (TSP) tested. First, the stability of the calibration bath was assessed. Then, the accuracy of 16 prototypes was evaluated for 7 target temperatures (ranging from 29 °C to 45 °C). Finally, the inertia of TSP response was evaluated while increasing and decreasing the bath temperature. The difference between prototype and target temperature increases as bath temperature moves away from 37 °C; however, the accuracy of the sensor conforms to applicable standards. Most TSP remain in the range of ±0.2 °C for each temperature level tested, but a linear, decreasing slope is observed; prototypes underestimate high temperatures and overestimate low temperatures. Data from time of inertia assessment show that probes were within the range of ±0.2 °C from the target temperature with a maximal delay of 150 s which satisfy standard norms. However, results indicate that a 1-point calibration procedure of the sensors appears non optimal, a 2-point calibration procedure should be performed to avoid the observed temperature data slope.