Patent ID: 8461513

Claim:
A device comprising: a substrate; a light emitting diode (LED) positioned on the substrate; a photodetector positioned on the substrate at a distance from the LED, wherein the photodetector is configured to sense light emitted by the LED; and a filtering material that covers the LED and the photodetector by a first thickness and a second thickness, respectively, and is positioned between an external environment and the LED and photodetector, wherein the filtering material includes a resin with an optical filtering property that provides a first level of attenuation in light emitted from the LED in the direction of the photodetector and provides a second level of attenuation in light emitted from the LED in the direction of the external environment where the first level of attenuation is substantially higher than the second level of attenuation, and wherein the resin is configured to provide the first and second levels of attenuation based on the lateral distance and the first and second thicknesses.