Pulse Rate Measurement using Android Smartphone

Photo-plethysmography is an optical technique which is used to measure the blood volume changes in the arterial blood in the peripheral circulation using a pulse oximeter. A pulse oximeter uses a bright LED at one end and a detector on the other end to measure the pulse rate and oxygen saturation. A low cost, homecare device that is easily operable by an individual can be designed using an android smart phone. The existing method of measuring the pulse rate consists of a Light Emitting Diode on one side and a detector on other side to measure the volume of blood changes. This paper proposes the methodology that is employed to measure the pulse rate from the video signal obtained using an available mobile phones camera. The Smartphone equipped with a LED flash light is applied for the intensity recording of the light reflected from the index finger due to the changes in blood volume. The mean values of the red channels are calculated and filtered using a butterworth band pass filter. In each frame, the red channel of the RGB signals that is recorded using a smart phone returned the useful plethysmographic information. The power spectral density analysis was performed on the filtered signal. Thus pulse rate can be estimated using this method. Both the normal and hypertensive patients are used as the subjects and the accuracy of the estimated value is calculated. The use of smart phone in medical imaging is the most encouraging one in the home based care or personal.