Use of Rolling Shutter and Pulse Transit Time for Continuous Blood Pressure Monitoring, 2013

Though a number of technologies can be used to calculate pulse transit time, we present a correlation between blood pressure and pulse transit time using two optical sensors for simultaneous two-point pulse detection. We also propose the use of the camera from a mobile phone to optically measure the photoplethysmographic (PPG) waveform as it travels from the heart through the blood. We resolve the PPG signal to 1 picosecond through use of the rolling shutter, a technique used in most low-cost camera sensors that renders each pixel row of an image one at a time. Pairing the sensor to custom optical processing, we can simultaneously measure the PPG waveform at multiple points without sacrificing time resolution. Our results support the optical measurement of pulse transit time to monitor blood pressure in patients continuously and with a minimally-invasive form-factor. (Ramesh Raskar, Athanasios G. Athanassiadis, Emmanuel Lim, John A. MacDonald, Savannah L. Niles)

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