Multichromatic porous silicon RGB rugate filters for use in smartphone biosensing

In this work, we report a porous silicon-based multichromatic rugate filter to select red (R), green (G), and blue (B) wavelengths from white light illumination provided by a smartphone. The full width at half-maximum values for all three color bands are below 30 nm. Spectral characterization was carried out with a spectrometer, and chromatic analysis was applied to smartphone images of the filter to verify the desired performance. Conversion of white light from the LED flash of a smartphone to multichromatic RGB illumination can be used in smartphone-based biosensing for improved limit of detection.