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In this paper a 0.13 μm CMOS front-end for drift chambers is presented. The front-end presents characteristics of low power consumption, which are well-suited in order to implement the cluster counting technique for particles identification. The front-end consists of a Variable Gain Amplifier (VGA) with 0, 10 and 20 dB gain steps and 1 GSa/s 6 bits Analog to Digital Converter (ADC). The VGA power consumption has been optimized according to the selected gain setting. The VGA power consumption is 8.4 mA, 9.4 Ma, 10.6 mA for 0, 10, 20 dB gain, respectively.

Planar Al/GaN/Ni Schottky diodes were realized on GaN films deposited on sapphire substrates and characterized in the dark and under illumination. The optoelectronic characteristics of GaN photodetectors appear largely influenced by structural defects and impurities, which are clearly detected in photocurrent yield measurements. In particular, an exponential increase of the photocurrent is observed and explained in terms of a barrier lowering photoeffect, hence a light induced shrinking of the space charge region, related to carrier trapping at defects and impurities. Trapping events are also responsible for a dispersive behavior of the AC responsivity with the light chopping frequency. Such effects point out the importance of a proper selection of bias voltage and working fre15quency for GaN photodetector operations.

Given the widespread applications of nanotechnology products, the evaluation of the potential hazards related to human exposures and environmental release of nanoparticles has become an urgent need. The development of a safety database for nanoscale particles is evolving as new particles, materials and exposure scenarios are being developed.

Liquid colloids are mixtures where one substance is dispersed evenly throughout another. Piezoactuators can be reliably used to sense physical properties of colloids. However, to better understand and forecast the behavior of the system, a suitable and reliable model should be used to fit experimental data. In this work we will show how the scattering parameters, introduced for the first time in this field, can greatly improve model identification accuracy and give deeper insight into the resonant response of the system, especially in the case of viscous systems, whenever resonance peaks tend to shift or to vanish. Any change on the density and/or viscosity of the interacting fluid causes a well-predictable modification on each possible frequency response computable from measured data: the best choice in terms of sensitivity and orthogonal correlation has been investigated by means of parametric simulations with variable loads. Experimental results demonstrate that the conceived sensor is able to reliably discriminate different bentonite clay suspensions.

Vertically-aligned carbon nanotubes (CNTs) films have been grown by radiofrequency plasma-enhanced chemical vapor deposition system onto alumina substrates, coated with 2.5 nm thick Fe catalyst, for NO2, H 2 and C2H5OH gas sensing applications, at sensor temperatures from room-temperature to 150°C. The CNTs appear in the form of forest-like structure. Nanoclusters of noble metals with nominal thickness of 5 nm of Pt, Ru and Ag have been sputtered on the top-surface of the vertically-aligned CNTs layers to enhance the gas sensitivity. It was demonstrated that the gas sensitivity of the metal modified CNTs-sensors significantly improved by a factor up to an order of magnitude through a spillover effect, and a broader selectivity was provided. The gas sensing properties of the CNTs-sensors, including the metal-modified CNTs, are characterized by a change of the electrical conductivity in a model of the charge transfer with a semiconducting p-type character. The metal-functionalized CNTs-sensors exhibit high sensitivity, fast response, reversibility, good repeatability, sub-ppm range detection limit. A practical application of the CNTs-sensors for monitoring landfill gas is presented. © 2010 Springer Science+Business Media B.V.

The current advances in ultra-low power design let foresee great opportunities in energy harvesting platforms for self-powered systems. This paper presents two conversion schemes based on active control for harvesting energy with a higher efficiency than traditional passive approaches. A prototype has been developed and the approaches have been validated for piezoelectric energy harvesters with both measurements in realistic conditions (i.e. irregular vibrations) and mixed-signal circuital simulations. The proposed converters may increase harvested power of at least 25% and up to three times with respect to a passive rectifier. The maximum harvested power is about 40uW in presence of weak vibrations (aRMS = 1.18 m/s2) obtained in a train passenger car in motion with a 28x6x0.5mm3 cantilever made of PZT-A4E with a 20g mass attached at the free end.