Olivier Ducloux

Vibrotactile using micromachined electromagnetic actuators array

One motivating application of this technology is the development of a tactile display interface, where discrete mechanical actuators apply vibratory excitation at discrete locations on the skin. Specifically, this paper describes the development fabrication and characterization of a 4 x 4 micro-actuator array of vibrating pixels for fingertip tactile communication. The vibrting pixels are generated by using an electromagnetic microresonator. The fabrication sequence and the actuation performance of the array are also presented.

Magnetically Actuated Microvalves for Active Flow Control

This paper describes the design, fabrication and characterization of silicon based, high flow rate microvalves for the active control of separated air flows. The fabricated system provides pulsed microjets with an outlet speed reaching 150 m/s at an actuation frequency ranging from static actuation to 2.2 kHz, using either electromagnetic actuation or a self oscillating mode. After a brief introduction, the microvalve dimensioning and fabrication process are presented. The actuation techniques used are then described and discussed.

MEMS for Flow Control: Technological Facilities and MMMS Alternatives

An introduction of MEMS in general is made. Then the paper provides an overview of essential MEMS devices already elaborated for different problems of flow control in aeronautics. In the last part, attention is focused on solutions based on Micro-Magneto-Mechanical Systems (MMMS).

Self-oscillation mode due to fluid-structure interaction in a micromechanical valve

This letter presents an original actuation mode for a micromechanical valve based on the induction of a self-oscillation, provided by the strong coupling between a mobile mechanical part and the fluid flow. The presented structure consists of a rigid silicon pad processed on a flexible membrane, both located over a silicon microchannel with structured internal walls. A theoretical analysis, based on a combination of the small perturbations method and a numerical study, shows that a self-oscillation can be induced on the mobile part due to the hybridization of the first flexion and torsion resonance modes interacting with the gas flow. Characterization of the self-oscillating microvalve shows high performances without electric energy supply for control.

Enhancement of biosensing performance in a droplet-based bioreactor by in situ microstreaming

A droplet-based micro-total-analysis system involving biosensor performance enhancement by integrated surface-acoustic-wave (SAW) microstreaming is shown. The bioreactor consists of an encapsulated droplet with a biosensor on its periphery, with in situ streaming induced by SAW. This paper highlights the characterization by particle image tracking of the speed distribution inside the droplet. The analyte-biosensor interaction is then evaluated by finite element simulation with different streaming conditions. Calculation of the biosensing enhancement shows an optimum in the biosensor response. These results confirm that the evaluation of the Damköhler and Peclet numbers is of primary importance when designing biosensors enhanced by streaming.

ADVACT an European Program for Actuation Technology in Future Aero-Engine Control Systems

The present paper will give an overview about the flow control activities in the project ADVACT launched within the EC 6th Framework. It is addressed to the identification and application of actuator technology for aircraft engines. The primary objective of ADVACT is to enable the achievements of improvements in operation, availability, costs and reduction of environmental impact of gas turbines by the provision of extended in-flight actuation and control of engine parameters.

A magnetically actuated, high momentum rate MEMS pulsed microjet for active flow control

A small-sized, high momentum rate (>10?2 N), dynamically actuated microvalve fulfilling the functional specifications for active aerodynamic flow control was designed, fabricated and characterized. The prototype consists of a microfabricated silicon channel pinched by an actuated poly(dimethyl siloxane) (PDMS) polymer membrane. Actuation is provided by coupling an inductive driving coil and a NdFeB permanent magnet fixed on the PDMS elastomeric membrane. The development of a specific microfabrication process, and a complete characterization of the fabricated prototypes are presented in this paper. The yield air microjet performances reach 150 m s?1 for an actuation frequency situated in the range [0 Hz?400 Hz] and an outlet area of about 1 . Experimental results also show that the use of a vectoring plate placed at the outlet of the microvalve provided not only easier integration of the microsystem, but also improved the penetration of the microjet into the main flow.

IEMN/LEMAC magneto-mechanical microjets and micro-hotwires and aerodynamic active flow control

An overview of the microjet and micro-hot wire solutions developed by IEMN/LEMAC during these last ten years for active flow control is presented. The IEMN/LEMAC microjet solutions are based on micro-magneto-mechanical systems (MMMS) and concern integrated devices delivering pulsed microjets, continuous microjets with bistable ‘On-Off’ actuation, and synthetic microjets. These devices were combined in arrays of eight to 32 elements distributed near the leading edge of a physical model of air wing, within an engine blade, inside an S-duct, around an engine exhaust and at the rear end of an Ahmed car model. Several wind tunnel experiments were made for separation control, and aero-acoustic control. It was demonstrated that the microjets satisfied the functional specifications defined by the industrial partners, as well as good robustness in severe wind tunnel environments. In addition, MEMS micro-hot wires for very local flow characterisations were also developed.

ONERA/IEMN Contribution within the ADVACT Program: Actuators Evaluation

This paper summarizes the ONERA/LEMAC contribution within the work-packages 2 and 3 of the EU project ADVACT. This activity is dedicated to the evaluation of pulsed jets based on magnetic actuation principle on a generic separated flow. It is supported by some advanced numerical work based on RANS/LES coupling.

Pulsed-Jet Micro-Actuators Evaluation for Flow Separation Control

We describe in this paper the efforts carried out within the EU project ADVACT to evaluate miniaturized (MMMS) pulsed jets in a basic experiment in which the separation is only caused by an imposed adverse pressure gradient. It is demonstrated that for a velocity ratio between the jet and the inflow velocity of 2, the micro-valves are able to induce a complete reattachment of the flow. Additionally, both controlled and uncontrolled flows are simulated using an advanced RANS/LES method.