DSP Based Wireless Reflectance Pulse Oximeter for Photoplethysmograms

Medical devices can be categorized into two categories which is invasive and non-invasive method. Invasive method needs medical device to be inserted into patient body regarding to check or do the treatment on the patients. However, the non-invasive method is a way to check the health condition from the outside of the body. A common non-invasive medical device is pulse oximeter. The function of the pulse oximeter is determining the percentage of oxygen in blood. Then, the based principle used to determine it is by calculating the intensity of transmitting light through the finger. Red and infrared light emitting diode (LED) is used to transmit the light and phototransistor works as a receiver. The hemoglobin in blood will absorb the light pass through the finger. Recently, there are many renovation has been made on this medical devices. Adding the parameter, showing the waveform of heart beat and wireless pulse oximeter are the new technologies on pulse oximeter. In this paper, the three parameters will be shown on the computer after go through the several parts. The ratio from intensity of red LED and infrared LED will be used to determine the value of heart rate and percentage of oxygen. The temperature sensor (LM35) also will be installed to obtain the body temperature. All the calculation and processing has been done by programmable board (Arduino Uno). Thus, the result would be appeared on the computer screen. The normal body temperature is about 37 C and the normal percentage oxygen in blood is 95 % to 99 %.