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Although Polydimethylsiloxane (PDMS) is one of the most widely used polymers, up to now there are few evidences of its application as gas sensor. In this work, we investigate the effects of volatile organic compounds (VOC) on optical and electrical PDMS physical properties. In the former case, cross-linked PDMS samples, exhibit a strong photoluminescence even when simply excited by a blue LED. The emission is stable in controlled air for several days and it quenches when exposed to several VOCs. As far as resistive sensors are concerned, the PDMS strong insulating properties have been modulated using commercial carbon blacks as conductive phase. Measurements of the electrical conductance variation vs. vapors concentration show a strong and fast response, even for concentrations in the order of hundreds of ppm. In this case, recovery seems to be the major problem.

We report on a new class of polymeric sensors based on a properly selected polysilsesquioxane filled with different conductive powders obtained by ball milling These sensors exhibit excellent sensing properties with respect to both polar and apolar analytes and do not base their operating mechanism on the swelling. In fact, exposure to water molecules or hexane vapours determines an increase of conductivity. In particular the response in the full RH% range for devices obtained with different filler (Zn-Graphite, Zn, Cu) is of four magnitude orders variation between 0% and 100% RH in the conductivity of the sensors.

Focused Ion Beam is used to realize two gas sensing devices machining as substrate a silicon/Si₃N₄ wafer and using single walled carbon nanotube ropes as sensitive element. Ionic beam is applied both for milling substrate and for platinum deposition. Sensors are characterized at room temperature introducing NH₃ and NO₂ gases in test chamber. A well defined resistance change is observed.

Polystyrene replica is realized preparing polystyrene and depositing the polymer onto a nanostructured porous silicon matrix used as a template. The thin polymer film is peeled off from the substrate and exposed to organic vapours. Swelling affects the optical reflectance and, by a specially adjusted set-up, the kinetic of the vapour desorption is measured in order to investigate replicas as drug delivery systems.

This study identifies an n-type porous silicon material that responds in a rapid and reversible manner to sulphur dioxide at room temperature, by an high quenching of its photoluminescence (PL), even at concentrations in the range of hundreds of ppb. PL quenching behaviour of this material has been investigated in nitrogen and in air, operating mechanism discussed, at the purpose of utilizing it for the fabrication of a stable device, that could satisfy the severe environmental requirements imposed by current laws.

Sensor Fusion by means of different architectural approaches has shown to be a powerful tool for the analysis of data produced by arrays of chemical sensors. In this work, we focus our attention on two sensor fusion architectures based on Multilayer perceptrons, applied to a small matrix (4–elements) of chemiresistors based on thin film polymer composites, in order to obtain significative enhancement in both gas estimation precision and sensor dynamic behavior (speed).

We propose an innovative PSP formulation in which pressure sensitive element is nanostructured silicon obtained in two different approaches and the binder is a polysilsesquioxane. The first approach is named top-down and consists in the dimension reduction of porous silicon powders assisted by a stain etching step. The other is a bottom-up one and consists in synthesizing nanometric silicon by metatheses reaction between silicon dioxide and carbon black, conducted in a ball milling reactor. We describe powders fabrication methods, formulation of our PSP and characterize paints performance.

In this work we present a study about behavior in physiological solution of two kind of nanomaterials, as carbon black and porous silicon. Dissolution of these nanoparticles have been controlled resulting in CB aggregation and PS solubility. These results are useful to evaluated the effects of nanoscale materials into biological system for understanding the human health implications.

A chemical gas sensor based on a single rope of single walled carbon nanotubes (SWCNTs) has been fabricated first isolating the rope on a silicon/Si₃N₄ substrate and then realizing, at its ends, two platinum microelectrodes by means of a Focused Ion Beam (FIB). Its electrical behaviour at room temperature in toxic gas environments has been investigated and compared to sensors based on bundles of SWCNT ropes. For all the devices upon exposure to NO₂ and NH₃ the conductance has been found to increase or decrease respectively. Response time in NO₂ is however faster for device based on the single rope. A mechanism for molecular sensing is proposed.

In this study we present a new class of sensors based on polysilsesquioxane-azulene system, that could detect various analytes by changing their conductivity and colour. This system represents one of the first example of guest-host polymer used in the sensor field. Taking advantage of the polysilsesquioxane properties in humid environment and of the brilliant blue azulene, an isomer of naftalene with high dipolar moment, we develop polymeric thin film that could work in high humidity conditions and detect different analytes useful in water analysis in a twofold response in terms of color change and conductivity variation.

Nano porous silicon (PS) membranes, obtained by electrochemical etch in fluoridric acid, were used to study the release characteristics of biomolecules through nanochannels. The release of dextrans biomolecules from the nanoporous membranes was deeply affected by material structure parameters, as well as molecular chemistry and concentration.

First results on fabrication of a Transdermal Drug Delivery device are presented. Device consists of two regions with different functions: one used for scrabbling the stratum comeum and injecting the drug and the other one used as drug reservoir. Device is manufactured starting from a silicon substrate where a porous silicon layer is obtained. Silicon substrate permits the integration of our device with a future electronic controller while biodegradable porous silicon is a good choice as drug reservoir. In order to test the device as drug delivery system, L-Ascorbic Acid impregnation has been evaluated by means of FTIR and BET analysis.

We look at an innovative method for the strain, stress measurement on surface. Our project is a simple imaging technique illuminating a polymer (PDMS) grid, attached on specimen, with a large spectra light source, and recording, with a ccd camera, the grid image obtained by diffracting light. Image acquired under stress is subtracted from one without stress giving a colour map of the surface correlated to the stress intensity. This technique arises from asserted optical techniques. Moreover, taking in account the technological progress (polymer, ccd, LEDs), we make the hardware setup very simple because it doesn't need coherent light source and the detector may be a commercial colour ccd.

In this work, we investigate the responses of an array of carbon black composite polymers to terpenoid vapours. In particular, the devices have shown current intensity changes upon exposure to specific concentrations of terpenoid vapours such as limonene, linalool and geraniol. The hypothesis used in order to qualitatively describe the sensors working mechanism assumes that the polymer swells when exposed to organic vapour and the swelling decreases the connectivity between the conductive filler particles. The filler dispersion, the morphology and the electrical stability of devices have been also evaluated.

In this work, we report on the electrical response of hydrogen sensor based on palladium nanowires array. Stability and selectivity are investigated at room temperature, in presence of 4% hydrogen concentration in nitrogen. Measurements show a clear stability of the devices in a few months and no interference by a variety of gases as well as relative humidity.

In this work we investigate the physical behaviour of various form of carbon nanoparticles in aqueous environment. The role of dissolution and the evolution of the aggregation state of MWCNTs, SWCNTs functionalized with water soluble polymer and carbon black nanoparticles in a PBS solution (Phosphate Buffered Saline) has been investigated. Nanoparticles solution were periodically checked for dissolution, with absorbance measurements, and DLS analysis. The different aggregation kinetics have been observed and discussed in terms of their possible toxicological role. Results showed that carbon based nanoparticles have a strong tendency to aggregate in aqueous environment. Even the water soluble SWCNTs aggregate in aqueous solution. In fact, within 24 hours small and/or solubilized particles disappear from solution and around 700 nm average particles are formed.

Herein Ink Jet printing technique is described for functional materials deposition. As a concrete application we report on the production and characterization of an all printed device for sensing applications, where piezoelectric printheads have been used to deposit, in opportune drop sequences, conductive Ag ink for the interdigitated electrodes and polystyrene/carbon black based ink for the sensing layer.