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Nair R.S.,Grenoble Institute of Technology | Perret E.,Grenoble Institute of Technology | Tedjini S.,Grenoble Institute of Technology | Baron T.,CNRS Microelectronics Technology Laboratory
IEEE Antennas and Wireless Propagation Letters | Year: 2013

This letter proposes, for the first time, a wireless passive chipless RFID tag for identification and humidity sensing applications. The proposed sensor tag, based on time domain, consists of cascaded group of transmission-line sections (C-sections) coupled at alternative ends capable of producing group delay peaks at a particular frequency. C-sections allow producing a unique ID for a tag. Sensing is achieved by depositing silicon nanowires on the strips of the C-sections group. Silicon nanowires are very sensitive to environmental humidity variation, which in turn changes the radar cross section (RCS), phase, and group delay of the tag. This feature is utilized for humidity sensor applications. The proposed sensor tag is experimentally verified. An RCS change of 30 dB and group delay variation of nearly 22.3 ns was observed near the fundamental frequency over a bandwidth of 40 MHz for a relative humidity variation of 60.2%-88%. Measurements were performed in a real environment. The obtained results confirm the very good potential of nanowires in humidity sensor applications. © 2013 IEEE.

Oehler F.,CEA Grenoble | Gentile P.,CEA Grenoble | Baron T.,CEA Grenoble | Baron T.,CNRS Microelectronics Technology Laboratory | And 3 more authors.
Nano Letters | Year: 2010

The state of the lateral surface plays a great role in the physics of silicon nanowires. Surprisingly, little is known about the phenomena that occur during growth on the facets of the wires. We demonstrate here that the size and shape of the facets evolve with the exposure time and the radial growth speed. Depending on the chemistry of the surface, either passivated by chlorine or decorated by gold clusters, the radial growth speed varies and the evolution of the facets is enhanced or impeded. If the radial growth speed is high enough, the faceting of the wire can change from top to bottom due to the exposure time difference. Three types of faceting are exposed, dodecagonal, hexagonal, and triangular. An evolution model is introduced to link the different faceting structures and the possible transitions. © 2010 American Chemical Society.

Honegger T.,CNRS Microelectronics Technology Laboratory | Berton K.,CNRS Microelectronics Technology Laboratory | Picard E.,CEA Grenoble | Peyrade D.,CNRS Microelectronics Technology Laboratory
Applied Physics Letters | Year: 2011

We propose a method to experimentally determine the Clausius-Mossotti factors and surface capacitances of colloidal particles. This two-step method is based on the following: (i) a precise positioning of particles on activated electrodes according to the applied frequency of an electric field and (ii) particles velocities measurements from a pure dielectrophoretic regime to build the Clausius-Mossotti factor. It confirms previous literature methods and measures the surface capacitance values for a wide range of particles such as polystyrene, silica, and gold whose diameters are at least 200 nm. © 2011 American Institute of Physics.

Zenasni A.,CEA Grenoble | Delamoreanu A.,CNRS Microelectronics Technology Laboratory | Rabot C.,CEA Grenoble
Applied Physics Letters | Year: 2012

Some advances in chemical vapor deposition process have provided noteworthy results toward the growth of large scale graphene. However, in contact with a neighboring material, graphene performances are usually reduced. Decoupling graphene from the substrate by suspension or intercalation is foreseen to recover its intrinsic properties. This work reports an original way for graphene suspension which occurs during its growth on platinum metal. This suspension arises above platinum silicide clusters which form during the annealing and induce the metal dewetting. The stretched graphene is highly corrugated because the clusterization of silicides structures induces additional stress. © 2012 American Institute of Physics.

Honegger T.,CNRS Microelectronics Technology Laboratory | Peyrade D.,CNRS Microelectronics Technology Laboratory
Journal of Applied Physics | Year: 2013

AC electrokinetics is becoming a strategic tool for lab-on-a-chip systems due to its versatility and its high level of integration. The ability to foreseen the behaviour of fluids and particles under non-uniform AC electric fields is important to allow new generations of devices. Though most of studies predicted motion of particles in co-planar electrodes configurations, we explore a pure 3-D AC electrokinetic effect that can open the way to enhance contact-less handling throughout the microchannel. By fabricating 3D microfluidic chips with a bi-layer electrodes configuration where electrodes are patterned on both sides of the microfluidic channel, we present a detailed study of the AC electrokinetic regimes that govern particles motion suspended in different host media subjected to a non-uniform AC electric field that spreads through the cross-section of the microchannel. We simulate and observe the motion of 1, 5, and 10 μm polystyrene particles relative to the electrodes and provide an insight on the competition between electro-hydrodynamical forces and dielectrophoresis. We demonstrate that using relevant electrode designs combined with the appropriate applied AC potential, particles can be handled in 3-D in the micro-channel at a single or a collective level in several medium conductivities. Both numerical simulations and experimental results provide a useful basis for future biological applications. © 2013 AIP Publishing LLC.

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