Microsystèmes Magnétiques Mag-MEMS - Solutions Cades

Work is in progress in collaboration with ONERA and
Silmach to integrate a high-efficiency Si-machined planar
turbine into the prototype, which will use combustion gases
from a low-temperature burner.
Other µ-generator projects include Allen's team at
Georgiatech [68] for high-power levels, as well as Holmes's at
Imperial College London [69] for low-power.
Optics
Deformable mirror for astronomy and ophthalmology
Ground-based telescopes suffer from atmospheric
turbulences which perturb the quality of the light arriving from
space. Astronomers use adaptive optics in order to correct the
wavefront of oncoming light. In this context, a first prototype
of electromagnetic miniature (ø 50 mm) deformable mirror
was developed, using micro-technologies available at IEMN in
Lille and LPMO in Besançon [70].
The first mirrors were composed of a thin polymer
membrane (2 to 5 µm) onto which was glued a matrix of
permanent µ-magnets, and of an array of planar µ-coils on a ø
50 mm substrate facing the membrane. The second generation
of mirrors uses 10 µm thick Si membranes developed at LETI,
and mechanically wound coils.
The behavior of the mirror allows deformations of up to
100 µm with currents in the range 1~3 A. Good linearity of the
deformation is observed up to 200 Hz, and best-flat down to a
few nm is achieved. The devices are now commercialised by
Imagine-Optics and Imagine-eyes, for both astronomy and
ophthalmology applications [71]. Magnetic actuation allows
for smaller pixels and more compact mirrors with huge
dynamics and fast response.
Other Mag-MOEMS
Many other optical Mag-MEMS can be found in the
literature. Most of them are magnetically activated mirrors for
scanners and fiber optic switching [72-74].
Other potential applications
We have described here only the Mag-MEMS developed
in Grenoble. Within the last decade, a great number of articles
have been published describing many prototypes of Mag-
MEMS with applications in a wide range of domains. The
reader is encouraged to explore in depth and width the many
excellent journals and conference proceedings, among which
the following ones are noteworthy:
• Journals: Journal of Micro Electro-Mechanical
Systems (JMEMS), Journal of Microsystems and
Microtechnology, Sensors and Actuators A
• Conferences: MEMS, Actuator, Transducers,
Intermag, MME, EMSA, Mecatronics
Power supplies, control, cooling
While electrostatic actuators use ‘high’ voltages and low
currents, Mag-MEMS require ‘high’ currents and low
voltages. Current pulses, if used, need faster control. Hence,
final performances highly rely on working conditions and
development of appropriate integrated supplies and coolers.
Also, for µ-sources, specifically dedicated power-electronics is
required in order to make use of the often low-voltage,
sometimes erratic energy and power levels produced by µgenerators.
Recent work on a converter for the above
mentioned µ-turbo-generator has yielded excellent results [67].
REMERCIEMENTS
Les Mag-MEMS présentés ici sont le fruit de nos
fructueuses collaborations principalement avec l'Institut Néel
(CNRS) et le CEA/LETI à Grenoble, et désormais au sein de
MINATEC. Ces projets sont financés par la DGA, le CNRS, le
Ministère de la Recherche et la Région entre autres.
REFERENCES
Mag-MEMS and scaling laws
[1] Microactionneurs electromagnétiques - MAGMAS, éd. O. Cugat,
Hermès/Lavoisier (2002), ISBN 2-7462-0449-5
[2] Édition révisée et en Anglais de [1]: Magnetic Microsystems Mag-
MEMS, éd. G. Reyne, J. Delamare & O. Cugat, ISTE (à paraître, 2008)
ISBN: 9781905209811
[3] O. Cugat, J. Delamare and G. Reyne, MAGnetic Micro-Actuator &
Systems MAGMAS, IEEE Trans. Magnetics, 39-6 (2003) pp.3608-3612.
[4] G. Reyne, J. Delamare and O. Cugat, Magnetic µ-actuators (Mag-
MEMS), Encyclopedia of Materials: Science and Technology Update
Online (EMSAT), Elsevier 2004, ISBN: 0-08-043152-6
[5] O. Cugat, G. Reyne, J. Delamare, H. Rostaing, Novel magnetic µactuators
and systems (MAGMAS) using permanent magnets, Sensors
and Actuators A 129 (2006) pp. 265–269
[6] Section B in Magnetic Nanostructures in Modern Technology, éds. B.
Azzerboni, G. Asti, L. Pareti & M. Ghidini (2007) ISBN:
9781402063367
[7] R.P. Feynman, There’s plenty of room at the bottom, (American Phys.
Soc. 26/12/ 1959), reprint J. MEMS, 1-1 (1992) pp. 60-66
[8] R.P. Feynman, Infinitesimal machinery, (Jet Propulsion Lab., 23 rd Feb.
1983), J. of MEMS, 2 (1993) pp. 4-14
[9] B. Wagner and W. Benecke, Magnetically driven µ-actuators: design
considerations. Microsystem Technologies 838 Springer Verlag Ed., 1990
[10] H. Guckel et al , Fabrication and testing of the planar magnetic
micromotor. J. Micromech. Microeng. 1 (1991) pp. 135-138
[11] W. Trimmer, Microrobots and micromechanical systems, Sensors &
Actuators A19-3 (1989) pp. 267-287
[12] D.K. MacKay and R.D. Findlay, An examination of the scaling
properties of electric micro-motors and their magnetic duals, IEE 5th
International Conference on Electrical Machines and Drives, London,
U.K., 11-13 Sept. 1991, pp. 170-174
[13] I.J. Busch-Vishniac, The case for magnetically-driven micro-actuators,
Sensors & Actuators A33 (1992) pp. 207-220.
[14] M. Jufer, Size limits and characteristic influence of electro-magnetic
actuators. Proc. 4 th International Conference on New Actuators (1994)
pp. 390-393
[15] W. Benecke, Scaling behavior of µ-actuators, Actuator, Bremen,
Gemany (1994), pp. 19-24
[16] H. Guckel, Progress in electromagnetic actuators, Actuator, Germany
(1996) pp. 45-48
[17] Z. Nami, C. Ahn, and M.G. Allen, An energy-based design criterion for
magnetic micro-actuators. J. Micromech. Microeng. 6 (1996) pp.337-344
[18] J.H. Fluitman and H. Guckel, Micro-actuator principles, Actuator,
Bremen, Germany (1996) pp. 23-28
[19] A. Kruusing, Actuators with permanent magnets having variable in
space orientation of magnetization. Sens & Act A101 (2002) pp.168-174
[20] G. Reyne, J. Delamare et al., Chapter 1 in [1, 2].
[21] J. Delamare, G. Reyne et al., Chapter 2 in [1, 2].