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Micro Robots
Sumit TripathiSaket Kansara
Outline
Introduction
Challenges Fabrication Sensors Actuators
MEMS Micro robot
Applications
Future scope
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.
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
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 conformationSubject to continuous rotation
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.
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
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
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
Cantilever Sensors
Detection Mechanismso Detect the deflection of a cantilever caused by surface stresseso 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:
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
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
Configuration Space
Bruce R. Donald, Member, IEEE, Christopher G. Levey, Member, IEEE, Craig D. McGray, Member, IEEE,Igor Paprotny, and Daniela Rus
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
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
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
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
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
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. BrooksMIT Artificial Intelligence Laboratory
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
Future Scope
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
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.html4) 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.