Dr' Vadim'Ya' Pokrovskii,

1
Microscanning optical projectors actuated by
quasi one-dimensional conductors

• Dr. Vadim.Ya. Pokrovskii,
• Kotelnikov Institute of
• Radioengineering and Electronics
• of Russian Academy of Sciences,
• Moscow, Russia.
• Dr. Maik Wiemer,
• Fraunhofer-Einrichtung für
• Elektronische Nanosysteme,
• Department Multi Device
  Integration,
• Chemnitz, Germany.

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Agenda / content

• Introduction MEMS-NEMS and the problems of
  actuation
• The basics Charge-density waves. Why actuators?
• Torsional strain of the CDW compounds and its
  characteristics
• Optical scanning devices, their purpose,
  construction, utmost parameters, limitation
• The project CDW-actuated optical scanner.

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MEMS-NEMS and the problems of actuation

• Efficient actuation is crucial to obtaining
  optimal performance from NEMS. As
  electromechanical devices are scaled downward,
  transduction becomes increasingly
  difficult,hampering efforts to create finely
  controlled integrated systems.
• Electromagnetic devices become ineffective below
  100?m
• Electrostatic are better, but fast drop of force
  with distance, needs nanoscale control. Need
  large elements plates, gates, and actually are
  not nano.
• Piezoactuation is universal, but require high
  voltage. Still, can be most effective for
  nanoscale C. Masmanidiset al., Science
  317,780,2007. Special arrangements are required
  for torsional strain.
• Exotic actuators elastomers, ion transport,
  electrolitic slow and/or weak.
• A powerful analog of piezoelectric would be an
  actuator required by a number of MEMS-NEMS. And
  this is proposed quasi 1-dimensional conductors
  with charge-density wave (CDW) directly provide
  large torsional strain.

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The CDW basics. CDW-lattice interaction.
u u0sin(qx?)
CDW sliding
? ?0sin(qx?)


CDW is deformable electronic crystal, a
spring inside the crystal.
In the simple 1D model the CDW and the lattice
should not interact. HOWEVER, the two springs
interact somehow giving rise to an analogue of
piezoelectric effect.
CDW
Lattice
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The CDW basics. CDW-lattice interaction.
u u0sin(qx?)
? ?0sin(qx?)


CDW is deformable electronic crystal, a
spring inside the crystal.
In the simple 1D model the CDW and the lattice
should not interact. HOWEVER, the two springs
interact somehow giving rise to an analogue of
piezoelectric effect.
CDW
Lattice
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?K0.3MoO3 CDW crystals
Experimental arrangements
For AFM
15?m
1mm
Photo of a TaS3 batch grown in IRE.
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• Torsional strain (TS) of TaS3 under electric
  field.
• Whiskers arrangement allows free torsion.
• Optical (mirror) methods for the strain
  registration are developed.
• Torsional strain up to 10o (shear 10-4
  at E300 mV/cm, piezomodulus gt10-4 cm/V) is
  observed a powerful intrinsic actuator.

Laser (0.63 ?m)
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High-frequency torsional response.Resonance
oscillations.
The Hi-f oscillations do not have a threshold
they are closely linear in voltage.
Frequency dependences of the oscillations
detected with the lock-in techniques, indicating
the resonance peaks. a,c. signal from the
photodiode b,d feedback signal from the sample.
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The fast contribution to the TS, temperature
dependences.
Temperature dependences of the ?? amplitude (?)
and Q-factor (?) at fixed VAC ?20 mV. The inset
shows the resonance frequency f0(T). The length
of the TaS3 whisker is 5 mm. Room-temperature
performance, f up to 200 kHz at least.
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The Project elaboration of the laser scanning
device for projecting television-like set-up.

• The present scanning set-up developed in
  Fraunhofer ENAS 1 based on electrostatic
  forces, demands relatively high voltages and is
  still limited in angle. E.g., with a voltage of
  380V the highest scanning angle achieved is 5.5-6
  degrees at resonance frequencies f24 kHz 1.
  The devices based on the quasi 1-dimensional
  conductors will give the same scanning angles
  with voltages at least 2 orders of magnitude
  lower even at room temperature. The dimensions of
  such a device would be an order of magnitude
  smaller.
• The devices are being elaborated as novel
  projecting technique for displaying video
  information and can be used, e.g., as a universal
  control panel
• 1 "MEMS Based Micro Scanners Components,
  Technologies and Applications", T. Gessner et.
  al, ACTUATOR 2006, 10th International Conference
  on New Actuators, 14 - 16 June 2006,
  Bremen, Germany, A6.0, p. 198.

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Features of the scanners elaborated
in ENAS.
Experimental setup for laser scanning projection
system
MEMS micro mirror spectrometer and its working
principle
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The goal and work schedule.

• A scanning device will be developed excelling
  the present elaboration in performance. A more
  general result expected is the demonstration of
  novel-type actuators opening a wide range of
  applications.
• Milestones
• 1) Studies of the TS of different quasi
  one-dimensional compounds at room temperature and
  comparison of their characteristics.
• 2) Choice of the q-1-D material and its
  detailed characterization. Synthesis, growth
  condition optimization.
• 3) Modification of micro scanners to be
  compatible with the CDW actuators.
• 4) Integration of CDW whiskers into
  microscanner.
  System characterisation.

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Thank you!

• Dr. V.Ya. Pokrovskii, IRE of RAS.
• 125009 Moscow, Mokhovaya 11-7
• pok_at_cplire.ru
• Cell 7(916) 443 15 43
• Tel.[phone] Fax [phone]

Dr. Maik Wiemer , Fraunhofer ENAS. Department
Multi Device Integration, Group Manager
TechnologyReichenhainer Strasse 88, 09126
Chemnitz, GermanyTel. 4937153971474Fax
4937153971310Mailtomaik.wiemer_at_enas.fraunhofer.
dehttp//www.enas.fraunhofer.de