Micro Robots

1. Micro Robots
Sumit Tripathi
Saket Kansara

2. Outline
Introduction
Challenges
Fabrication
Sensors
Actuators
MEMS Micro robot
Applications
Future scope

3. Introduction
Programmable assembly of nm-
scale (~ 1-100 nm){μm-scale (~
100 nm-100 μm)} components
either by manipulation with larger
devices, or by directed self-
assembly.
Design and fabrication of robots
with overall dimensions at or
below the μm range and made of
nm-scale {μm-scale} components.
Programming and coordination of
large numbers (swarms) of such
nanorobots.

4. FABRICATION
Materials:
Polymer actuators( Polypyrrole (PPy) actuators):
Can be actuated in wet conditions or even in aqueous solution.
Have reasonable energy consumption.
Easily deposited by electrochemical methods
Titanium-Platinum alloy
Used to manufacture electrodes
Corrosion resistant
Titanium adhesive alloy, high fracture energy(4500 J/m2 or more)
Silicon substrate: capability of bonding between two surfaces of same or different material
Carbon nanotubes:
Assembly of aligned high density magnetic nanocores
Flexible characteristics along the normal to the tube’s axis
Extremely strong
 Biological proteins, bacteria etc.
Image: Berkeley University

5. Actuator-Rotary Nanomachine.
The central part of a rotary nanomachine.(Figure courtesy of Prof. B. L. Feringa’s group (Univ of Groningen.)
Power is supplied to these machines electrically, optically, or chemically by
feeding them with some given compound.
Rotation due to orientation in favorable conformation
Subject to continuous rotation

6. Drawbacks of molecular machines of This
Kind
Moving back and forth or rotating continuously
Molecules used in these machines are not rigid

Wavelength of light is much larger than an individual machine.

Electrical control typically requires wire connections.
The force/torque and energy characteristics have not been
investigated in detail.
Rotary Nanomachine.

7. Motor run by Mycoplasma mobile
Image credit: Yuichi Hiratsuka, et al.
 Bacterium moves in search of protein rich regions.
The bacteria bind to and pull the rotor.
Move at speeds of up to 5 micrometers per second.
Tracks are designed to coax the bacteria into moving in a uniform
direction around the circular tracks.
Protrusions

8. Motion of a Mycoplasma mobile -driven rotor.
Image credit: Yuichi Hiratsuka, et al.
Some Other Types:
Chlamyodomonas : Swim toward light (phototaxis)
 Dictyostelium amoeba crawl toward a specific chemical substance (chemotaxis).
Each rotor is 20 micrometers in diameter

9. Cantilever Sensors
Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland,Canada
θ=Angle of incidence
Φ=Azimuthal angle
Nc is the surface normal to cantilever
ξ =Angle of inclination of PSD

10. Cantilever Sensors
Detection Mechanisms
oDetect the deflection of a cantilever caused by surface stresses
o Measure the shift in the resonance frequency of a vibrating cantilever
Drawbacks
Inherent elastic instabilities at microscopic level
Difficult to fabricate nanoscale cantilevers
Image: L. Nicu, M. Guirardel, Y. Tauran, and C. Bergaud
(a) cantilevers (b) bridges.
Optical microscope images of SiNx:

11. Micro-Electro-Mechanical-System
60 μm by 250 μm by 10 μm
Turning radius 160 μm
Speed over 200 μm/s
Average step size 12 nm
Ability to navigate complex paths

12. The state transition diagram of USDA
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

13. Configuration Space
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

14. Steering Arm subsystem
• Dimple dimension .75 μm
• Disk radius 18 μm
• Cantilever beam 133 μm long
 Controls direction by raising and
lowering the arm
 Simultaneous operation with
scratch drive
 Control in the form of oscillating
voltages
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

15. Control Waveforms
Drive waveform actuates the robot
Forward waveform lowers the device voltage
Turning waveform increases the device
voltage
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

16. Power delivery mechanism
Uses insulated electrodes on
the silicon substrate
Forms a capacitive circuit with
scratch drive
Actuator can receive
consistent power in any
direction and position
No need of position restricting
wires
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

17. Device Fabrication
Surface micromachining process:
Consists of three layers of
polycrystalline silicon, separated
by two layers of phosphosilicate
glass.
The base of the steering arm is
curled so that the tip of the arm is
approximately 7.5 μm higher than
the scratch drive plate
Layer of tensile chromium is
deposited to create curvature
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

18. Electrical Grids
Consist of an array of metal electrodes
on a silicon substrate.
Electrodes are insulated from the
substrate by a 3 μm thicklayer of
thermal silica
Coated with 0.5 of zirconium dioxide
High-impedance dielectric coupling
Silicon wafers: oxidized for 20 h at 1100C in
oxygen
Wafers are patterned with the “Metal” pattern
Three metal layers are evaporated onto the
patterned substrates
Middle layer consists of gold-Conductive
Two layers of chromium-adhesion layers
between the gold, the oxidized substrate, and
the zirconium dioxide
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,
Igor Paprotny, and Daniela Rus

19. Some Other Kinds
Piezoelectric motors for mm Robots
Not required to support an air gap
Mechanical forces are generated by
applying a voltage directly across the
piezoelectric film.
Ferroelectric thin films (typically 0.3-
μm), intense electric fields can be
established with fairly low voltages.
High torque to speed ratios.
μ Robots Driven by external Magnetic
fields Include a permanent magnet
Can be remotely driven by external
magnetic fields
Suitable for a mobile micro robot
working in a closed space.
Pipe line inspection and treatment
inside human body.
Anita M. Flynn, Lee S. Tavrow, Stephen F. Bart and Rodney A. Brooks
MIT Artificial Intelligence Laboratory

20. Applications
See and monitor things never
seen before
Medical applications such as
cleaning of blood vessels with
micro-robots
Military application in spying
Surface defect detection
Building intelligent surfaces
with controllable
(programmable) structures
Tool for research and
education
Micro robot interacting with blood cells

21. Future Scope

22. Future Scope
Realization of ‘Microfactories’
Self assembling robots
Use in hazardous locations for planning resolution
strategies
Search in unstructured environments, surveillance
Search and rescue operations
Space application such as the ‘Mars mission’
Self configuring robotics (change shape)
Micro-machining

23. Acknowledgements
1) B. L. Feringa, “In control of motion: from molecular switches to molecular motors,” Acc. Chem.
Res., vol. 34, no. 6, pp. 504–513, June 2001.
2) H. C. Berg, Random Walks in Biology. Princeton, NJ: Princeton Univ. Press, 1993.
3) http://www.physorg.com/news79873873.html
4) K.R. Udayakumar, S.F. Bart, A.M. Flynn, J.Chen, L.S. Tavrow, L.E. Cross, R.A. Brooks and
D.J.Ehrlich, “Ferroelectric Thin Film Ultrasonic Micromotors”Fourth IEEE Workshop on Micro
Electro Mechanical Systems, Nara, Japan, Jan. 30 - Feb. 2, 1991.
5) JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 1, FEBRUARY 2006
1An Untethered, Electrostatic, Globally Controllable MEMS Micro-Robot Bruce R. Donald,
Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,Igor
Paprotny, and Daniela Rus
6) K.W. Markus, D. A.Koester, A. Cowen, R. Mahadevan,V. R. Dhuler,D.Roberson, and L. Smith,
“MEMS infrastructure: The multi-user MEMSprocesses (MUMPS),” in Proc. SPIE—The Int. Soc.
Opt. Eng., Micromach.,Microfabr. Process Technol., vol. 2639, 1995, pp. 54–63.