Porous silicon waveguides

Rong G, Najmaie A, Sipe JE, Weiss SM (2008) Nanoscale porous silicon waveguide for label-free DNA sensing. Biosens Bioelectron 23 1572-1576... 

Porous Silicon Waveguides for Small Molecule Detection... 

Here we focus on the capabilities of a porous silicon waveguide biosensor for the detection of small molecules. The porous silicon waveguide, shown schematically in Figure 3a, consists of two porous silicon layers. Light is trapped in the top, high refractive index layer, based on total internal reflection at the interfaces with air and the bottom, low refractive index porous silicon... 

Figure 4 shows the relationship between the porous silicon waveguide resonance shift and electric field interaction with biomolecules, in this case 24-base pair DNA, inside the porous silicon waveguide. In this first order analysis (25, 24), the total power of the field and its distribution remains constant while... 

Calculations have been performed to estimate the detection limit of the porous silicon waveguide biosensor based on the percent of optical power interacting with biomolecules in the waveguide (25). The sensor is capable of detecting pictogram quantities of small molecules in a 1 mm surface area. The detection limit depends on the number of probe molecules immobiUzed on the pore walls, the size of the biomolecules relative to the size of the pores, and the efficiency at which the probe molecules capture the target species. 

Figure 4. The response of the porous silicon waveguide sensor upon exposure to biomolecules depends on the percent of the optical field interacting with the molecules. The inset shows the field distribution in the waveguide with the majority of the field inside the porous silicon (LP = low porosity layer, HP = high porosity layer) where biomolecules may be captured. Therefore, even if only a few biomolecules are present in the waveguide, they can be detected...

Figure 5. Experimental measurement of porous silicon waveguide resonance after several functionalization steps and exposure to either (a) complimentary DNA, (b) non-complimentary DNA, or (c) buffer solution. The small shift due to DNA hybridization is easily within the resolution of the prism coupler rotation stage of0.002°. (d) Histogram summarizing the selectivity of the porous silicon waveguide sensor to 24 base pair DNA. DNA hybridization (complimentary DNA shift) can be clearly distinguishedfrom the low level of non-specific binding (mismatch DNA shift) and the noise floor of the measurement system...

Oton, C. J. Navarro-Urrios, D. Capuj, N. E. Ghulinyan, M. Pavesi, L. Gonzalez-Perez, S. Lahoz, F. Martin, I. R. Optical gain in dye-impregnated oxidized porous silicon waveguides. Appl. Phys. Lett. 2006, 89, 011107/1-011107/3. 

Najar A, Charrier J, Ajlani H, Lorrain N, Haesaert S, Oueslati M, Haji L (2008) Optical gain at 1.53 pm in Er3 -Yb3 co-doped porous silicon waveguides. Mater Sci Eng B 146 260-263... 

Wei X, Kang C, Rong G, Retterer ST, Weiss SM (2009) Porous silicon waveguide with integrated grating coupler for DNA sensing. In Fauchet PM (ed) Frontiers in pathogen detection from nanosensors to systems, vol. 7167, SPIE... 

Fig. 1 Schematics of porous silicon waveguides consisting of (a) one, (b) two, or (c) three porous silicon layers. Light is confined in a high refi active index (low porosity) porous silicon layer when surrounded by lower refi active index media, which can include a higher porosity porous silicon layer, air, or another low index solid, liquid, or gaseous substance...

Balucani M, Bondarenko V, Dolgyi L, Lamedica G, Ricciardelli A, Viarengo E, Vorozov N, Ferrari A (2000) Bending properties in oxidized porous silicon waveguides. Mater Sci Semicond Process 3(5-6) 351-355... 

Balucani M, Bondarenko V, Lamedica G, Ferrari A, Dolgyi L, Vorozov N, Yakovtseva V, Volchek S, Petrovich V, Kazuchits N (2001) Er-doped oxidised porous silicon waveguides. Thin Solid Films 396(l-2) 201-203... 

Ferrand P, Romestain R (2000) Optical losses in porous silicon waveguides in the near-infrared effects of scattering. Appl Phys Lett 77(22) 3535-3537 Haji L, Hiraoui M, Lorrain N, Guendouz M (2012) Anti resonant reflecting optical waveguide structure based on oxidized porous silicon for label free bio sensing applications. Appl Phys Lett 100(11) 111102... 

Wei X, Weiss SM (2011a) Guided mode biosensor based on grating coupled porous silicon waveguide. Opt Express 19(12) 11330-11339... 

Wei X, Mares JW, Gao Y, Li D, Weiss SM (2012) Biomolecule kinetics measurements in flow cell integrated porous silicon waveguides. Biomed Opt Express 3(9) 1993-2003... 

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