Girolamo Di Francia | Search PubMed

PubMed2006

Silicon infrared diffuser for wireless communication.

We show what we believe to be a novel way to use silicon in infrared radio communication as a suitable material for the realization of optical diffusers in the range of 850-1600 nm. A crystalline silicon wafer is made porous by means of electrochemical etching. The porous silicon produced is optically characterized, and measurements report a high reflectance in the band of interest. We also study the angular distribution of diffused radiation by the porous silicon surface at different angles of incident radiation. Measurements show that radiation diffuses in a quasi-Lambertian manner, confirming the good performance of this material as an incident radiation diffuser.

Journal Article↗

PubMed2005

Towards a label-free optical porous silicon DNA sensor.

We report on the fabrication of an optical silicon-based label-free DNA sensor. n-Type crystalline silicon wafers have been electrochemically etched to form porous silicon layers and characterized in terms of porosity, pore distribution, surface composition and photoluminescence. Samples (0.25 cm(2)) have been cut and properly derivatized using trimethoxy-3-bromoacetamidopropylsilane in order to link single strand DNA (ss-DNA). Such a molecule is not commercially available and has been ad-hoc prepared by reacting hydrobromic acid and 3-aminopropyltrimethoxysilane in presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide as coupling agent. Trimethoxy-3-bromoacetamidopropylsilane acts as a bridge anchored to the porous silicon surface through the silane group while immobilizing ss-DNA by means of the bromoacetamido moiety. We have found that derivatized samples exhibit a photoluminescence that is stable in time and is not modified after exposure to non-complementary DNA strand. On the other hand, a sensible enhancement of the light emission has been observed when the derivatized samples react with the complementary strand, showing that the specific ss-DNA/complementary DNA (c-DNA) interaction can be optically sensed without using further labeling steps. This strongly strengthens the possible role of silicon as a material for biosensors.

Biosensing Techniques↗