Porous silicon based infrared photonic-sensor for high sensitive heavy metal ion detection

In this paper we report the development of an ultrasensitive photonic sensor based on nanoporous silicon (NPS) substrate for heavy metal ions detection in a FTIR reflection system. A one-dimensional photonic crystal with disturbed Bragg reflector (DBR) fabricated by successive electrochemical etchings (ECE) is employed to enhance the reflected IR signals [1] [2]. This well-defined NPS nanostructures will be red shifted due to the increase in the refractive index of the Fe³⁺ ion solution (1 mM). The Fe³⁺ with difference concentration due to difference spectrum shift, and the average sensitivity is 22.3cm^-1/mM corresponding to a detection limit of 10.8 ppm.