Miles, Nicolas,Crowe, John,Hayes-Gill, Barrie,Grubb, Mark
申请号：
AU2007242649
公开号：
AU2007242649B2
申请日:
2007.04.11
申请国别(地区):
AU
年份:
2013
代理人:
摘要：
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 representative of the modulation signal. The demodulator is insensitive to any phase difference between the modulation signal and the oscillator of the demodulator. From the demodulated output, a signal indicative of blood volume as a function of time and / or blood composition is generated. 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.
