Photoplethysmography
US11103150B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 2014 |
| Grant date | Aug 31, 2021 |
| Priority date | — |
| Expiry date | Mar 5, 2038 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/14552
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A photoplethysmograph device includes a light source for illuminating a target object. A modulator drives the light source such that the output intensity varies as a function of a modulation signal at a modulation frequency. A detector receives light from the target object and generates an electrical output as a function of the intensity of received light. A demodulator with a local oscillator receives the detector output and produces a demodulated output, insensitive to any phase difference between the modulation signal and the oscillator, indicative of blood volume as a function of time and/or blood composition. A number of demodulators may be provided to derive signals from multiple light sources of different wavelengths, or from an array of detectors. The plethysmograph may operate in a transmission mode or a reflectance mode. When in a reflectance mode, the device may use the green part of the optical spectrum and may use polarising filters.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.