This work was carried out in the framework of the European project BOND (Bioelectronic Olfactory Neuron Device, http://bondproject.org/) aimed at using ORs carried by nanoscale liposomes as sensing elements of an electrochemical array, for specifically detecting target odorants from complex odorant mixtures. This project has potential applications in medical diagnosis, but also in agroalimentary or cosmetics quality control, security, and environment.

New fabrication technologies and, in particular, new nanotechnologies, have provided biomaterial and biomedical scientists with enormous possibilities when designing customized surfaces that can be used as novel supports for cell culture studies or in other biomedical applications as biosensors. The main issue now is how to effectively design these components and choose the appropriate combination of structure and chemistry to tailor towards applications as challenging and complex as stem cell differentiation. In this talk, the main strategies developed by the Nanobioengineering group at IBEC for the design and fabrication of surfaces with controlled topography and chemistry at the micro and nanoscale will be reviewed. The group has been working in new applications of techniques as nanoimprint lithography, focused ion beam lithography, microcontact printing, piezo-jet deposition and dip-pen nanolithography in the biomedical field.

Olfactory receptors (OR) constitute the key elements in the fantastic performance of the animal olfactory system. These receptors are located in the plasmic membrane of the ciliae of olfactory neurons, which are bathed by a layer of aqueous mucus that protects the olfactory epithelium [1]. Olfactory receptors can be expressed in vitro in various expression systems, as in yeast cells for instance [2]. These heterologously expressed olfactory receptors could be used in the development of artificial olfactory biosensors [3]. In order to transfer and immobilize the olfactory receptors onto the biosensors, one possibility is to prepare small lipidic nanosomes from the membrane fraction of the cells. In the present communication we report on the AFM characterisation of these nanosomes in the case of the rat I7 OR. The rat I7 olfactory receptor has been expressed in yeast (S. ceverisae) [2]. Localization of I7 olfactory receptor expressed in yeast has been performed by immunocytochemistry and confocal microscopy, revealing the presence of the receptor at the plasma membrane. A highlevel of functional expression has been demonstrated through a luciferase reporter. In addition, immunogold labeling of the I7 OR expressed in S. cerevisae followed by electron microscopy revealed its ultrastructural functional localization in the yeast membrane and in its trafficking pathway. Immunoblot analysis and glycosylation studies has shown that the I7 receptor is present as a mannose-glycosylated monomer. The level of expression of the I7 receptor has been quantified to be around 1.5x 10 receptors/yeast cell, which is quite high for this type of receptors.Yeast cells were then mechanically disrupted and the plasma membrane fractions were separated from unbroken cells and cell walls by serial centrifugation steps. Inspection by transmission electron microscopy (TEM) of negatively stained membrane fraction adsorbed onto formvar-coated grids reveals that it is composed of circularized nanosomes or unclosed fragments with sizes ranging from 500nm to 40nm. Their size can be homogenized to 40-60nm by additional sonication. TEM images however, do not provide a three dimensional representation of the adsorbed nanosomes. In order to overcome this limitation, atomic force microscopy images were performed. To this end, the membrane fraction was simply deposited and adsorbed onto a mica susbtrate and imaged in tapping mode in air with a commercial Atomic Force Microscope. Probes with constant force k=0.9 N/m and resonant frequency 40 kHz were used in order to minimize the damaging of the nanosomes.Nanosomes with diameters ranging from 200 nm down to 40 nm, and heights ranging from 30 nm down to 10 nm, respectively, have been identified in the images (see Fig 1). The 3 dimensional structure of the adsorbed nanosomes (Figure 2) is compatible with the spherical structure of the nanosomes in solution although due to the adsortion process the aspect ratio is far from unity (as would be the case for a sphere). The important point to be noted is that the nanosomes do not break upon adsorption, since the height is much larger than twice the membrane thickness (10 nm), therefore indicating that the nanosomes still contain some aqueous solution inside. This may depend on the nanosome-surface interaction and be different upon deposition on a functionalized surface. To our knowledge, this is the first time this type of nanosomes incorporating olfactory receptors has been imaged upon adsorption onto a substrate. Note that the number of receptors in the smallest nanosomes is expected to be between one and ten. Acknowledgements: Financial support from the European Comission through the SPOTNOSED project is gratefully acknowledged. Poster

We show our work developed on smart transducer systems controlled via communication network such as CAN or Ethernet. We have chosen the IEEE-1451 standard as a basic lines to fit. This normative tries to settle down a new concept in the way of working with transducers, simplifying and unifying the procedure and hardware needed. We have worked within the IEEE1451 standard, implementing complete nodes according to this normative. Each node includes two subsystems, a STIM and an NCAP.

Multiexponential decays may contain time-constants differing in several orders of magnitudes. In such cases linear sampling results in very, long records featuring a high degree of oversampling. Here, we analyze a nonlinear linear time scale transformation to reduce the total number of points with a minimum signal distortion achieving an important reduction of the computational cost of subsequent analyses. We propose a time-varying filter whose length is optimised for minimum quadratic error

A 14-bit MOSFET-only 2(n) order)-E modulator for capacitive sensors interfaces has been implemented using a 0.7um CMOS process. The circuit is based in the substitution of linear capacitors by MOS capacitors in a Switch capacitor architecture. The circuit present low fabrication cost, small area, and high matching. The proposal was tested comparing two different)-E modulators, one with linear capacitors and the MOS-only version. Similar results were obtained for both modulators.

Three thermal oxidation methods aimed at growing thin SiO2 films have been considered: Low temperature oxidation, O-2-diluted oxidation, and Rapid Thermal Oxidation (RTO). These procedures differ not only in their oxidation temperature but also in the thermal uniformity that is possible to achieve across the wafer. The electrical evaluation of the test capacitors show that longer times-to-breakdown are attained by the RTO samples for thicknesses down to 50 Angstrom. The observed behaviour is explained in terms of the different mechanical stress levels in the different samples due to their different oxidation temperatures according to viscoelastic relaxation considerations and is further confirmed by the analysis of their FTIR spectra. Despite their better intrinsic breakdown features, RTO oxides exhibit more defect related failures that arise from wafer stress related problems due to the spatial thermal gradients that are characteristics of RTO operation. (C) 1998 Elsevier Science B.V. All rights reserved.

A CAD tool for the automated generation of behavioral models in HDL-A is presented. This CAD tool has been implemented in the frame of a project for the automatic modeling of microsystem components for the co-simulation with VHDLor Spice-models. Starting from the finite-element-description of a microcomponent a nonlinear behavioral HDL-A-model is generated by successively adding or deleting effects to the HDL-A-model according to the observed differences between the two models. Using the example of a micromembrane the practicability of this approach is demonstrated. This CAD tool provides a method for decoupling the generation of behavioral models from the finite-element-simulation process.