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. 2008 Oct 23;8(10):6549-6556.
doi: 10.3390/s8106549.

Porous Silicon Based Resonant Mirrors for Biochemical Sensing

Edoardo De Tommasi  1 , Luca De Stefano  2 , Ilaria Rea  2   3 , Valentina Di Sarno  2   3 , Lucia Rotiroti  2   4 , Paolo Arcari  5 , Annalisa Lamberti  5 , Carmen Sanges  5 , Ivo Rendina  2
Affiliations

Porous Silicon Based Resonant Mirrors for Biochemical Sensing

Edoardo De Tommasi et al. Sensors (Basel). .

Abstract

We report on our preliminary results in the realization and characterization of a porous silicon (PSi) resonant mirror (RM) for optical biosensing. We have numerically and experimentally studied the coupling between the electromagnetic field, totally reflected at the base of a high refractive index prism, and the optical modes of a PSi waveguide. This configuration is very sensitive to changes in the refractive index and/or in thickness of the sensor surface. Due to the high specific area of the PSi waveguide, very low DNA concentrations can be detected confirming that the RM could be a very sensitive and labelfree optical biosensor.

Keywords: DNA Optical Biosensors; Porous Silicon; Resonant Mirrors.

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Figures

Figure 1.
Figure 1.
Experimental setup. DL: diode laser emitting s-polarized radiation at 785 nm; L: lens with focal length f=7.5 cm; RM: resonant mirror; RS: rotation stage; PM: power meter on an independent rotation stage.
Figure 2.
Figure 2.
Schematic of the functionalization process, from the oxidized PSi chip to the covalent attachment of the DNA single strands.
Figure 3.
Figure 3.
Resonant peaks of the waveguide, corresponding to four guided modes in TE polarization at 785 nm, after functionalization with APTES and GA.
Figure 4.
Figure 4.
Numerical simulations of RM spectra as a function of the air gap thickness
Figure 5.
Figure 5.
PSi RM resonances after functionalization with probe DNA and after two DNA hybridization steps: the coupling angle shifts demonstrate the molecular interaction between the probe DNA and its complementary target at different concentration.
Figure 6.
Figure 6.
Resonance shifts of the waveguide mode coupling angle as a function of the DNA concentration.
See this image and copyright information in PMC

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