We present here our first results in micro-machining using a Ti:Sapphire femtosecond laser operating at 800 nm and 5 kHz repetition rate. Fast prototyping of microfluidic circuits in pyrex glass and cyclo-olefin-polymer (COP) is reported.

Bulk acoustic waves excited in thin piezoelectric films have revealed their capabilities for addressing the problem of high frequency RF filters (above 1 GHz). In this paper we propose an alternative to thin film deposition consisting in single crystal wafers bonded on a substrate (for instance silicon or glass) and thinned, allowing for plate thickness close to 10 mu m. This has been achieved on 3 inches wafers and allows for an accurate selection of the wave characteristics. More, the properties of the piezoelectric material are found conform with tabulated values, enabling one to reliably design ally passive signal processing device.

Micro-machined Ultrasonic Transducer (MUT) structures are periodic, associating numerous elementary actuators. These transducers can be accurately analysed or even designed using mixed finite element analysis/boundary element methods (FEA/MEM). In this work, we report on the design and test of a cMUT structure based on a thin silicon membrane shaped in order to comply our modelling assumptions.

A new type of electrochemical cell has been developed for use in electrochemical, chemical and biological applications. Using a platinum microelectrode as working electrode, this cell incorporates a silver microelectrode as reference electrode. These microelectrodes, whose area is equal to 1μm2, were fabricated using photolithography, sputtering, and focused ion beam (FIB) technologies since these micro-fabrication techniques allow us to develop miniaturized electrochemical cells useful either for nanoelectrochemistry or biosensors applications. In this study, we show it is possible to coat a surface by chemical or biological compounds by immersing the microelectrodes in a solution, then setting a difference of potential between the two microelectrodes of the cell. For example, we used this miniaturized cell to realize the electrochemical polymerization of aniline into polyaniline to show that this electrochemical cell is efficient to coat a surface with a thin film of polymer.

The miniaturization of refrigerating systems represents a very current scientific and technical challenge to improve the performances of numerous electronic components. This work presents a global approach to the problem and suggests studying the cooling by means of small channels filled with an oscillating gas: the double inlet pulse tube refrigerator (DIPTR). A great level of miniaturization based on the technology of carving silicon is exposed. This study proposes to apply an electric analogy for modeling both hydrodynamic and thermal phenomena. Considering the complexity of the theoretical problem including mechanical, thermal, thermodynamical, and acoustic considerations, the authors take care to summarize the main governing equations in a particular form so any scientific engineer could understand the DIPTR principle.

Potentiometric pH sensors based on linear polyethylenimine (L-PEI) and linear polypropylenimine(L-PPI), two synthetic enzymes and biocompatible polymers, films were prepared by electropolymerization of three different monomers: ethylenediamine (EDA), 1,3-diaminopropane (1,3-DAP) and diethylenetriamine (DETA) in order to be used in clinical, dermatological and biological applications, such as in vivo analysis. In a first step a biosensor was tested which consisted in a platinum wire protruded from glass sheath. The polymer film coated on these platinum electrodes showed good linear potentiometric responses to pH changes from pH 3 to 10. Resulting electrodes present both good reversibility and good stability versus time. The effect of the different polymer film thicknesses to potentiometric responses was also studied. This study allowed us to develop a miniaturized pH biosensor in the second step. This sensor was fabricated using photo-lithography, followed by sputtering and lift-off processes, and it included an electronic detection system. We have also successfully studied the potentiometric responses to pH changes of this device over a period of 1 month, and so we propose this new pH micro-biosensor as an alternative to classical pH sensors currently used in dermatology.

The cooling of electronic components is of great interest to improve their capabilities, especially for CMOS components. The purpose of this paper is to present the principle and the design of a micro cooler dedicated to such application. The originality of the approach concerns both the use of a thermodynamic system and the use of a micro-fabrication technology entirely compatible with the small scale of the component. The cooling function is assumed by a pulsed gas in a small canal (pulse tube) made of glass and of silicon. Specific micro heat exchangers, also made of silicon, have been designed from the results of a study concerning both the pressure drop and the transitory thermal response. The actual micro-cooler performances are estimated in an experimental way by means of temperature and pressure measurements.

This paper describes in details the fabrication and tests of a micromechanical connector, which is used for the precise optical self-alignment of multi-waveguide optical integrated circuits (OIC) to ribbon optical fibers, without injecting light in the fiber. Nickel alignment pins are electrodeposited on the OIC using a photolithographic process, and these pins are inserted into suitable openings made on a silicon micromachined platform, on which optical fibers are accurately positioned using V-grooves. A simultaneous fabrication of several microstructures which are used as an assistance for the assembly of the fibers and the waveguides is presented for the first time. Design and fabrication issues are reported, as well as preliminary experimental results which show that excess optical losses on the order of 3dB per coupling facet can be obtained.

The design, fabrication and measured characteristics of a bulk-micromachined focusing device are presented. A micro-bench is formed by 2 V-grooves which support an optical fiber and a micro-lens. A thermal actuator is integrated in the optical bench, and allows a micro-lens to be moved along the optical axis in order to adjust longitudinally its focusing spot. This device can be used for vision systems such as robotic vision or confocal microscopy. The focusing range can be adjusted between 50 mm and infinity with a 15 mA supply current.

This paper describes the fabrication of a new mechanical microconnector, which is used for the precise optical self-alignment of multi-waveguide Optical Integrated Circuits (OIC) to ribbon optical fibers, without injecting light in the fiber. Nickel alignment pins are electrodeposited on the OIC using a photolithographic process, and the pins are inserted into suitable openings made on a silicon micromachined platform, on which optical fibers are accurately positioned using V-grooves. Design and fabrication issues are reported, as well as preliminary experimental results which show that excess optical losses on the order of 3 dB can be obtained

The microfabrication of silicon V-grooves allows to obtain very good positioning accuracies, it is therefore often used for precise alignment of optical fibers. In many cases, it is necessary to etch at the same time V-grooves with variable widths, or V-grooves crossing each other. In such commonly encountered cases, well-known overetching effects appear, leading to structures that are quite uncontrolled in size and depth. Corner compensation methods can reduce such effects to some extent, in some cases.In this report, we present another method which can be used to minimize convex angles overetching. This method can be used alone or in addition to classical corner compensation methods. In some cases, it could even be used when such method are not possible.We first present the convex angle overetching, and derive the relation between underetching and etching depth. The method relies on discontinuities of the mask, which allow to keep a precise etching geometry until the discontinuity is underetched : the beginning of the corner underetching is thus delayed while the wanted structure is etched with a high accuracy. The control of the underetching rate is obtained through a precise alignment between the mask edges and the crystal orientation. The experiments show that our method allows to reduce significantly the overetching of convex angles.This method is useful to improve or simplify the fabrication of several kinds of microstructures for MEMS or MOEMS applications. We show how it makes feasible a microstructure which mixes closely spaced V-grooves and metal interconnection lines, and how it can improve the fabrication of crossing microchannels.