Agnès Tixier

A silicon shadow mask for deposition on isolated areas

A shadow mask with high pattern flexibility is realized by deep reactive ion etching (RIE) on Si wafer. The novel features of the mask are the presence of a mechanical alignment structure and of patterns with isolated islands inside them. The advantage of this shadow mask is the possibility of deposition of any kind of pattern shape by evaporation or sputtering on a sample that is precisely positioned. Moreover, by this technique, deposition is realized without damaging electronic devices or micromachined structures on the sample. Precise positioning of the sample with respect to the shadow mask is allowed by the mechanical alignment structures. Some doughnut-shape-like patterns are obtained by deposition through the patterns with isolated islands inside them. In this article we will describe the realization and the application of such a shadow mask.

Embedded-mask-methods for mm-scale multi-layer vertical/slanted Si structures

Complicated deep-etched structures having multiple heights and vertical/slanted walls have realized by fully-silicon-based batch fabrication process, which only needs lithography on a flat surface. Arbitrary numbers of mask layers were laminated on the initial surface of a substrate and deep-RIE, LOCOS or anisotropic wet etching were performed to make microstructures using each mask layer subsequently.

Catching and attaching cells using an array of microholes

The authors succeeded in moving and catching cells using an arrayed microholes structure combined with an immobilized antibodies layer. One microhole caught one cell. The success rate of catching cells was almost 100%. Cells are moved toward microholes with liquid flow into these microholes. Around the microholes, patterned gold was deposited and antibodies were chemically attached to it. When the cells met the antibodies placed around the microholes on the patterned gold, they attached to them. The cells were first vacuumed by the liquid flowing through the microholes then fixed by the antibody. This is the key technology to improve the efficiency of DNA insertion into cells in gene therapy. The active part of the microsystem is able to inject genes into cells using a microcapillary array injector. The microholes ensure two functions: firstly to attract and isolate cells towards the active part by means of aspiration, and secondly to inject genes into cells. The antibodies ensure the immobilization part.

3-D microsystem packaging for interconnecting electrical, optical and mechanical microdevices to the external world

This paper reports the realization of a pigtailed silicon platform with 8 WDM filters based on a new 3-D packaging technology. Four silicon pieces are released out of a silicon wafer by using ICP-RIE as a very accurate dicing tool. One edge of the piece containing the filters is patterned into pin-shapes to be vertically inserted into a mother board with electrical connections. A V-groove board for the optical fibers is mechanically aligned in the mother board. This technology enables precise assembly of active optical devices with ribbon fibers, electrical connections to 3-D micromechanical subsystems and reconfiguring the system in the module level.

Bulk Micromachined Durable Air-Flow Microactuator Array for Robust Conveyance Systems

A durable air-flow microelectromechanical conveyer is batch-fabricated and tested. The conveyer has a rigid surface without any fragile protrusions, which have tended to hinder microconveyers from being used for real-world applications. Small objects placed on the actuator array were successfully carried by the air flow. The conveyer did not break even after rough treatment with metallic tweezers and fingers.

Realisation of a Cell Manipulation Bio-Microsystem using Shadow mask techniques

The main achievement presented in this paper is the use of a new non-lithographic technique for the patterning of antibodies-linking surfaces, on defined areas of biomicrosystems (BioMEMS). This new technique, called shadow mask technique permits high ratio of biomolecules-linking, as it avoids any photolithography resist pollution of the activated surfaces. Moreover it is compatible with microelectronics techniques, and permits thus very precise alignment with the other layers (microelectrodes, microcapillaries) of the bioMEMS.

A Multilayer Microelectrode Array for Particle Separation by Dielectrophoresis

This paper focuses on the use of dielectrophoresis (DEP) for particle separation. Our purpose is to design a chip that enables the manipulation of thousands of particles at the same time, using a large 2D-microelectrode array. Several electrode shapes were designed with the goal of obtaining high field gradients and ensuring a good separation between the locations of the field maxima and minima, where the particles are respectively directed under positive and negative DEP. Two different microsystem designs have been tested. The first structure is composed of two interdigitated networks of tip electrodes. The second structure is multilayer and arrays a set of electrodes producing a quadrupole field.

Design of a pigtailed tunable filter for optical fiber transmissions at 1.3 to 1.55 μm

A micromechanically tunable Fabry Perot filter where the optical wavelength is tuned by moving a slider in the cavity is designed: the Fabry Perot filter is an air cavity in which the optical path ca be increased by inserting a transparent slider; the tuning effect depends on the thickness of the slider. Using a methodology based on a parametric investigation of the technological parameters, the design of a filter is proposed: a lower sensitivity to the position of the slider in the cavity is expected to realize the device using silicon micromachining.