Most temperature indicators that use thermocouples as sensors include an internal thermometer for compensating room temperature variations. This thermometer measures ambient temperature, which is then converted to a thermoelectric voltage. This voltage is added to the electromotive force measured in the thermocouple sensor and then converted back to temperature. Although precise calibration of the indicator can be conducted in a controlled room-temperature environment, additional uncertainty arises due to room temperature compensation during actual measurements. To address this issue, we calibrated temperature indicator at the ice point. In this experiment, the indicator was placed in an environment where the temperature varied between 8 and 38oC, demonstrating its dependency on ambient temperature. In a second set of experiments, we shorted the thermocouple input terminal to verify whether the indicator correctly indicated the ambient temperature. This study proposed a method to assess additional uncertainty that must be considered when using a thermocouple connected to an indicator calibrated with an external ice point in a laboratory. It also highlights additional steps and factors to consider during the calibration of temperature indicators that employ internal temperature compensation.

Pressure sensors are widely used in industries, including cars and coolers. Highly accurate pressure sensors are capable of corresponding to changes in the surrounding temperature. Additionally, the manufacturing process of pressure sensors greatly impacts the cost and degree of precision. This study undertook to examine the manufacturing process of pressure sensors, especially those using ceramic diaphragm. Ruthenium oxide (RuO2) was used instead of strain gauge for piezoresistance. TC thermistor (temperature coefficient) resistance compensated for changes in outdoor air temperature. Furthermore, thick-film resistors were precisely adjusted with laser trimming technology. These processes resulted in the production of a high accuracy diaphragm pressure sensor having an ability to correspond to changes in outdoor temperatures.