Mirrors reveal a lot about a person – wrinkles, laugh lines, blood pressure… what? Blood pressure? That's what a graduate student in the Harvard – MIT Health Sciences and Technology program is working on.
So far, Ming Zher Poh has been able to get accurate pulse measurements from ordinary low-resolution webcam imagery. His prototype is built into a mirror with a display at the bottom. An earlier researcher had proposed using expensive camera equipment. Graduate students Poh and Daniel McDuff, seen in the photo, along with professor Rosalind Picard published their paper in the journal Optics Express.
McDuff looks into pulse-reading mirror – Credit: Melanie Gonick
Poh is expanding the scope of the project to include measuring respiration and blood oxygen levels. Eventually, he will attempt to measure blood pressure too. Light variations in brightness produced by the flow of blood cursing through the blood vessels in the subject's face are used to track the pulse beat. Software is used to discern the face in the webcam video image. Red, green and blue sensors produce the image and the digital information obtain is broken down into separate pieces of data.
The readings the team obtained compared favorably to the results obtained from an FDA approved finger blood volume pulse (BVP) sensor. Poh even has adapted a signal-processing technique that was developed to isolate one voice from a group of voices in order to deal with movement and differences in ambient lighting.
Remotely measuring the cardiac pulse can mean comfortable physiological assessment without electrodes. The technique of reading bodily functions in a mirror could replace having to place sensors on a burn victim or could be used over the Internet as a initial screening device when monitoring a patient.