Ams OSRAM SFH 7018 enables wearable devices to achieve high-quality heart rate and blood oxygen measurements

Ams Osram has announced the release of a new multi-color LED package, the SFH 7018, with a radiation intensity more than 40% higher than the previous generation, which improves the accuracy of PPG (photoelectric plethysmography) measurements in smartwatches, wristbands and other wearables.

The SFH 7018 features a high-reflectivity QFN (square flat pin free) package that significantly improves light output. In addition, the improved two-cavity design places green leds separately from red leds and infrared (IR) leds: spacing and optical isolation ensure optimal light source placement relative to photodiodes, and reduce interference between green light (for heart rate measurement) and red and infrared light sources (for blood oxygen saturation or SpO2 measurement). Green chips do not cause red and infrared chips to fluoresce due to cross excitation at shorter wavelengths.

The optimized size of the surface-mount QFN package is only 0.6mm high, making it easy to integrate the module into any type of wearable device. Despite its compact size, the SFH 7018 offers dual-drive capabilities that optimize forward voltage redundancy and reduce overall power consumption.

Dr. Sergey Kudaev, Senior System Architect at AMS OSram, said: "With the new SFH 7018, wearable device manufacturers can significantly improve the quality of the optical signals on which heart rate and blood oxygen measurements depend, making such measurements more accurate and reliable in all operating conditions. When it comes to measuring vital signs, SFH 7018 helps improve the accuracy and absoluteness of heart rate, blood oxygen levels and even more advanced parameters such as blood pressure."

Increase the radiation intensity and increase the signal-to-noise ratio

The radiation intensity of SFH 7018 is significantly increased: Compared to the existing SFH 7016, the SFH 7018's red and infrared LED brightness is increased by more than 40%, the green LED brightness in the SFH 7018A version is increased by 80%, and the green LED brightness in the SFH 7018B version is more than doubled. In red, green and infrared wavelengths, the SFH 7018 also far outshines today's best-performing competitors.

Due to scattering and absorption phenomena (depending on various factors), the light signal in the tissue is weak, on this basis, the detection of light signal micromodulation is a major challenge for all vital signs monitoring equipment, so the amount of light emitted by the LED will have a great impact on system performance. When more light reaches the photodiode after the blood flow changes, the signal quality is improved, resulting in improved measurement accuracy and repeatability. The SFH 7018 achieves superior performance by sending more light into the body.

The SFH 7018 is available in two versions: The SFH 7018A is optimized for low forward voltage at high current and can operate without an expensive booster. The SFH 7018B is optimized for maximum radiation intensity.