Measurement of Body Vitals using Photoplethysmography (PPG) and Smartphone Sensors

Every day, millions of people use portable health gadgets to monitor body vitals such as heart rate, blood oxygen level, blood pressure, etc. However, this can also be facilitated just by using normal smartphones which are commonly available. Thus, this paper aims to provide first aid in the measurement of body vitals for early diagnosis of symptoms. The outcome of this paper is a framework to measure the key body vitals such as blood oxygen, heart rate, blood pressure and respiratory rate using the built-in sensors in a smartphone namely a camera, flashlight, accelerometer, and microphone. These vitals are captured by analyzing the photoplethysmography (PPG) signals obtained from the red intensities of the images of the fingertip and performing further arithmetic calculations on the obtained values. On the other hand, respiratory rate is calculated using the deviation in the values obtained in the accelerometer readings during the movement of the chest upwards and downwards. All the algorithms are computationally feasible on mobile devices and make use of the built-in smartphone sensors only, without the need for external devices. Also, smartphones have become cheaper than before and more people in the society have access to it, thus giving them a wider reach. The paper also compares the values for the vitals measured on pulse oximeters, blood pressure monitors, health bands, and smartphones with low-and high-quality cameras. Comparisons are made on a sample size of 100 measurements, and the mean percentage error for each type of body vital measurement is calculated with respect to each measuring device.