About

A finger photo-plethysmograph (PPG) is a noninvasive transducer that measures relative changes in blood volume or the oxygen saturation in a subject’s finger. The blood volume pulse (BVP) sensor reads the relative changes in blood volume. The pulse oximeter reads the oxygen saturation in the arterial blood. These instruments employ the same measuring principle, which is based on the red and infrared light absorption characteristics of oxygenated and deoxygenated hemoglobin. Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through. Deoxygenated (or reduced) hemoglobin absorbs more red light and allows more infrared light to pass through.With each heartbeat, the change in arterial blood volume momentarily increases or decreases the amount of Hb and HbO2. This results in the absorption of more light during the systolic phase and less light during the diastolic (resting) phase of the heart during any given beat. The photodiode output level is affected by variation in the level of light absorption. Hence, we obtain a waveform output level and determine the peaks between heartbeats.Our monitoring system contains three principal devices: a ring sensor, a telemetry manager, and a monitoring station server. The ring sensor, which is worn around the user’s finger, collects the heart rate data and sends it to the caretaker connected wirelessly.When an emergency develops, the telemetry manager quickly and automatically sends short messaging services (SMS) and instant messages via the WCDMA or the internet (TCP/IP) to the monitoring station server. The telemetry manager may be a mobile phone or an internet phone.We are also planning to develop the mobile phone application for continuous pulse rate monitoring of the patient

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