Development of Safety Warning Instruments in Far-Infrared Rays Physical Modalities for The Elderly

Far-infrared rays physical modalities (FIR-PM) are famous equipment for physical therapy of muscle aches that is a regular health issue in the elderly. During the Covid -19 pandemic, this equipment is more important due to therapy privacy. However, far-infrared rays can affect burn skin because the distance is improper or takes too long when used on the same area of skin when. According to a survey of the demand for FIR-PM in the elderly aged more than 60 years old, 23 persons. The result found 60% of the elderly used FIR-PM and 50% of the elderly are concerned about the effects of FIR therapy while setting the price of the equipment about lower than 3,000 baht. Most of the cheap-cost FIR-PM do not have a safety system that might cause harm to the user. Therefore, the aim of this study is the development of safety warning instruments in FIR-PM. First, an experiment to find a proper distance. The study used pig skin the value of the absorption coefficient nearby human skin. The samples' before and after temperatures must be no more than 5.40^oC for FIR-PM to be used safely. The experiment was conducted at a distance between the heat source and the sample at 20, 25, 30, 35, and 40 cm for 60 min. The temperature was recorded from the sensor every 10 min. The results showed that the proper distance and time were 35 cm for 40 min. The temperature of the pig skin samples was increased to 3.34°C which is suitable for physical therapy and does not burn skin. Then, develop safety warning instruments (SWI) for the equipment by connecting the Arduino UNO R3 board with Relay Module, Active Buzzer, and Ultrasonic Module HC-SR04. SWI will be a warning sound when the user is at an inappropriate distance. Instrument performance testing showed instruments control system was able to effectively stop working following the specified distance. The accuracy value of SWI was more than 90%. Other than SWI will stop working for 40 min after starting physical therapy.