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Picture: Vital Sign Monitoring. ©OSRAM
Technology for optical sensors for vital sign monitoring applications is advancing at a fast pace. In days of Covid the use of photoplesythmography (PPG) sensing for heart rate and blood oxygenation has become a key feature for wearable and medical devices.
As a pioneer in the area of optical sensors, Osram has been a key supplier from the very beginning when wearable products started their success in the consumer market.
With in-depth knowledge of optical sensing systems, Osram innovated the use of rectangular photodiodes in PPG sensors in our second-generation fully integrated Biofy modules, SFH 7070 (175-7445) and SFH 7072 (174-7444) . Rectangular photodiodes offer the advantage of higher signal quality when compared to a photodiode of the same size with a square shape.
The reason is straightforward. More light is reaching the photodiode at the edge of the silicon that is closest to the emitting LED. The portion of silicon further away is reaching significantly less light and does not contribute much to the signal. Why not eliminate this portion of the photodiode? And here comes the rectangular-shaped detector.
As more wearable applications are attaching sensors to new locations on the body, as in form of patches, headbands, etc. Osram offers now the advantage of the rectangular photodiode for use cases where the customer wants to have full freedom of design in various geometric combinations of emitters and detectors.
The SFH 2703 (201-9552) gives customers full flexibility for any configuration in an ultra-slim and compact package. Green light offers the strongest signal for heart rate PPG signals. In order to eliminate ambient IR light the SFH 2713 (201-9554) adds an IR cut filter that allows it to increase signal strength for heart rate PPG applications. The SFH 2703 is the ideal solution for SPO2 sensing where IR and red light is used.
In combination with our award-winning LED technology in form of single LEDs or multi-emitters (SFH 7016, SFH 7015) the new series of photodiodes SFH 2703 / 2713 offers the newest photodiode technology to enable the next generation of wearable devices.
For more information about Health Monitoring click here: https://www.osram.com/os/applications/health-monitoring-and-fitness-tracking/index.jsp