Vol.9 (2019) No. 6 ISSN: 2088-5334 Comparative Study on the Measurement of Human Thermal Activity Awais Gul Airij #1 , Rubita Sudirman # , Usman Ullah Sheikh # , Teruji Ide + , Yusuke Nagata + , Kiyotaka Kamata + # School of Electrical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Skudai, Johor, Malaysia E-mail: * gaawais2@live.utm.my + National Institute of Technology, Kagoshima College, Kagoshima, Japan Abstract— Human physiological signals measurement is the necessity of today’s modern world. The physiological signals, including heart rate, skin conductance, temperature, and pupil diameter, are significant indicators of underlying problems or illnesses and aid in indicating the underlying condition non-invasively. This study highlights the importance and needs for only one physiological signal, which is the body temperature as even a minor change in temperature values has a unique effect on the body. Hence, the present study focuses on comparing two well-known temperature sensors, namely DS18B20 and LM35, which are among the top choices for many temperature-based applications. The two sensors are compared in terms of cost, accuracy, temperature range, voltage, output type, implementation, packaging and required signal conditioning circuitry. The sole purpose is to find the adequacy of only one in terms of medical applications. The temperature readings are collected for 15 seconds from 10 participants between the age of 25 – 28 years and the data is sent to a microcontroller, which is Arduino Mega board. The microcontroller board processes the data for noise and artefacts removal and displays the final temperature readings on the serial monitor of Arduino IDE. The results highlight that DS18B20 is more accurate and robust in comparison to LM35, as it has lower fluctuations in the readings and is not affected by user movements. This study will help in the future development of healthcare systems, which may track the user’s thermal changes accurately in real-time. Keywords— arduino; healthcare; non-invasive; physiological signals; sensors; temperature. I. INTRODUCTION Monitoring human physiological signals is state of the art nowadays. A lot of time and money has been put into researching cost-efficient and accurate measurement techniques of human physiological signals. The most commonly measured physiological signals found in other researches are heart rate variation, skin perspiration, pupil diameter, respiration rate and temperature [1], [2]. Each physiological signal has its own importance and provides with a different information that needs to be interpreted and utilized accordingly. These signals represent parameters related to the physiological function of the circulatory, neurological, and respiratory systems and are measured with the help of multiple sensors. However, the present study only focuses on the measurement of only one physiological signal, which is the temperature. The measurement of warmth and coldness of an object is known as temperature. The well-known scales for temperature measurement are Celsius (°C), Fahrenheit (°F), and Kelvin (°K). The increase or decrease in body temperature is an indication of some underlying problem or infection. The importance of temperature and how it affects the human body functions can be understood by a simple analogy stating as almost everything depends on the variation of temperature. For instance, in an electrical conductor, if the temperature is increased, the resistance also increases. Furthermore, temperature measurement is also necessary for agricultural [3], industrial, and many other engineerings [4]–[8] and medical applications [9], [10]. The thermoregulatory system of the body lies in the hypothalamus, and its role is to maintain the average body temperature, which is in the range of 36.1°C – 37.2°C [11]. Though this range is affected by the age and the measurement site. Table I shows the different temperature ranges in different human body parts depending on the age of a person. The humans are homeothermic; therefore, their internal thermoregulatory system maintains the temperature at 37°C ±1. Any temperature range below or higher than the normal range will adversely affect a person’s health or is an indication of an underlying problem [12]. Both extreme hot and cold temperatures affect an individual adversely and can be fatal at times. 2160