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Porous silicon based one-dimensional photonic crystals, such as Bragg mirror and optical microcavity, has been modified by infiltration of a new biocompatible polymer, an amino functionalized poly([variant_greek_epsilon]-caprolactone) (PCL-NH2), and characterized as optical biochemical sensors. The entrapped polymer adds strong chemical stability to the nanocrystalline matrix on exposure to alkaline solutions preserving the device sensing abilities in monitoring volatile substances and chemical compounds. On the basis of these results, these hybrid structures can be proposed as a high performance platform for biochemical applications. [ABSTRACT FROM AUTHOR]

Wetting phenomena in porous silicon layers are experimentally investigated by Raman scattering. The experimental results show a reversible blue-shift of Raman spectra of wetted porous silicon layers with respect to the unperturbed layers. We ascribe the shift to a compressive stress due to the increased lattice mismatch between the porous silicon layer and the bulk silicon substrate in wetting conditions. [ABSTRACT FROM AUTHOR]

In the last years, the possibility of light generation and/or amplification in silicon, based on Raman emission, has achieved great results. However, some significant limitations, inherent to the physics of silicon, have been pointed out, too. In order to overcome these limitations, a possible option is to consider low dimensional silicon. Along this line of argument, an approach based on Raman scattering in porous silicon is presented. We prove two significant advantages with respect to silicon: the broadening of spontaneous Raman emission and the tuning of the Stokes shift. Finally, we discuss the prospect of Raman amplifier in porous silicon. [ABSTRACT FROM AUTHOR]

In the last three years, the possibility of light generation and/or amplification in silicon, based on Raman emission, has achieved significant results. However, limitations inherent to the physics of silicon have been pointed out, too. In this letter, an approach based on Raman scattering in porous silicon is investigated. Two significant advantages with respect to silicon are proved: the broadening of spontaneous Raman emission and the tuning of the Stokes shift. Finally, we discuss about the prospect of Raman amplifier in porous silicon. [ABSTRACT FROM AUTHOR]

Time-resolved measurements of red-shifts in the reflectivity spectra of porous silicon multi-layer microcavities, due to exposure to vapor of chemical species, give deep insight about the spatial concentration of the liquid condensed into the pores. Results clearly indicate that capillary condensation starts immediately and proceeds homogeneously all over the stack, yielding a uniform concentration distribution. [Copyright &y& Elsevier]

Large, repeatable and selective red-shifts in the reflectivity spectra of porous silicon microcavities (PSMs) have been registered after exposure to vapour or dip into liquid aliphatic hydrocarbons with different molecular weights. The shift in the resonant peak of the optical microcavity is due to average refractive index changes, induced by capillary condensation of the organic species into the silicon pores. [Copyright &y& Elsevier]

Abstract: Porous silicon biosensors are by far used in optical monitoring of molecular interactions. These photonic devices could greatly benefit of integration with specific microfluidic circuits that allow small volume, and thus low consumption of reagents, fast time of incubation, and highly controlled reaction conditions. In this paper, we summarize the experience of our research group in fabrication and characterization of optical biochip, and also present new, original results on biosensing. In particular, a porous silicon based microarray of one-dimensional photonic crystals has been integrated with innovative microfluidic circuit for parallel feeding of chemical solutions. The device has been used for the label free optical monitoring of ssDNA–cDNA interaction. [Copyright &y& Elsevier]

Abstract: The compatibility of porous silicon and anodic bonding technologies for the realization of sensing micro-components in lab-on-chip applications is demonstrated. In particular, we have developed and tested an innovative anodic bonding process: voltage, time and temperature have been properly matched in order not to affect the properties of the transducing material, which can be strongly modified by thermal treatments through oxidation. Two devices for chemical and biological sensing have been designed, fabricated and tested. The results obtained are very promising, especially regarding further integration of porous silicon and glass with optical and microelectromechanical instruments. [Copyright &y& Elsevier]