Showing papers by "Giancarlo Canavese published in 2011"

A multilevel Lab on chip platform for DNA analysis

Abstract: Lab-on-chips (LOCs) are critical systems that have been introduced to speed up and reduce the cost of traditional, laborious and extensive analyses in biological and biomedical fields. These ambitious and challenging issues ask for multi-disciplinary competences that range from engineering to biology. Starting from the aim to integrate microarray technology and microfluidic devices, a complex multilevel analysis platform has been designed, fabricated and tested (All rights reserved—IT Patent number TO2009A000915). This LOC successfully manages to interface microfluidic channels with standard DNA microarray glass slides, in order to implement a complete biological protocol. Typical Micro Electro Mechanical Systems (MEMS) materials and process technologies were employed. A silicon/glass microfluidic chip and a Polydimethylsiloxane (PDMS) reaction chamber were fabricated and interfaced with a standard microarray glass slide. In order to have a high disposable system all micro-elements were passive and an external apparatus provided fluidic driving and thermal control. The major microfluidic and handling problems were investigated and innovative solutions were found. Finally, an entirely automated DNA hybridization protocol was successfully tested with a significant reduction in analysis time and reagent consumption with respect to a conventional protocol.

Comprehensive Characterization of Large Piezoresistive Variation of Ni-PDMS Composites

Abstract: This work presents a comprehensive investigation of the piezoresistive response of a metal-polymer composite for robotic tactile sensor application. Composite samples, based on nickel nanostructured conductive filler in a polydimetihylsiloxane (PDMS) insulating elastomeric matrix, were prepared changing several process parameters like thickness, composition of the polymer and nickel filler content. A variation of electric resistance up to nine orders of magnitude under applied uniaxial load was measured in the fabricated samples. Cost efficient materials, simplicity of the process, large sensibility, and harsh environment compatibility make this quantum tunnelling composite adapted to be integrated as sensing coating in space robotic applications.

Giant piezoresistive variation of metal particles dispersed in PDMS matrix

Abstract: An Investigation of the piezoresistive response of a metal-polymer composite based on nickel conductive filler in a polydimethylsiloxane (PDMS) insulating matrix for tactile sensor application is presented in this paper. Lacking a mechanical deformation, the prepared composites show no electric conductivity, even though the metal particle content is well above the expected percolation threshold. In contrast, when subjected to uniaxial compression, the electric resistance is strongly reduced. A variation of up to nine orders of magnitude was registered. The thickness of the insulating layer between particles decreases when the sample composite is compressed. Therefore, the electric conduction which is related to a tunneling phenomena, increases exponentially. This behavior is further enhanced by the presence of very sharp nanometric spikes on the particles surface which act as field enhancement factors. In the presented work, the piezoresistive behavior of the composite, the stability in time of the resistance value and the response to several cycles of compression and decompression are evaluated on samples with different physical parameters like nickel content, PDMS copolymer/curing agent ratio and thickness.