Design of Clinical Thermometer Calibration Instrument Based on PID System

A body temperature thermometer is a measuring equipment that must be calibrated periodically according to a specific standard. An extensively employed media for calibrating thermometers in the present day is one that requires a considerable amount of time to reach a stable temperature. The objective of developing this tool is to incorporate PID controls to minimize measurement errors and achieve a more stable and rapid temperature control for calibrating the thermometer. To achieve this, one must assess and analyze the impact of temperature stability on the calibration media of the thermometer, as well as examine the heating elements and temperature sensors of the LM35. The study employs a minimal system for data processing, utilizing the PID system as a temperature controller for the heating element. The LM -35 sensor is used as the temperature sensor, the flashlight serves as the heating medium, and the LCD is used for display purposes. The measurements were conducted at temperatures of 37°C, 39°C, and 41°C. The thermohygrometer measurements were compared to a calibration device, resulting in an average error or difference of 0.27°C at a temperature setting of 37 °C, 0.31°C at a temperature setting of 39°C, and 0.33°C at a temperature setting of 41 °C. This indicates that the temperature variation at each location is lower than the average of 1 °C.