magnetically- and bacteria-actuated mobile micro-robots · 2015. 10. 14. · micron scale mobile...

1

© Metin Sitti, MPI/CMU

Magnetically- and Bacteria-Actuated Mobile Micro-Robots

Director, MPI for Intelligent Systems, Stuttgart, Germany

Professor, Carnegie Mellon University, Pittsburgh, USA

21 November 2014


Outline

•  Introduction

•  Bacteria Propelled Swimming Micro-Robots •  Magnetically Actuated Micro-Robots

•  Conclusions

2


Small Scale Perception, Control and Action

An Amoeba during Phagocytosis


Small Scale Biological Coordination and Swarming

S. Pratt, ASU Collective food retrieval by ant teams

H. Berg, Harvard Swarming of Salmonella typhimurium

3


Characteristics of Micro-Robots •  Small scale physics and dynamics:

–  Increased surface area to volume (S/V) ratio:

•  Surface forces/drag/friction >> Inertial forces –  Sticky & dissipative world!

•  Fluidics: low Reynolds number (Re) –  Inherently nonlinear, fast and stochastic dynamics –  More sensitive to disturbances

S/V = 10-4 /mm Re = 108

0.4 body length/sec

S/V = 103 /mm Re = 10-4

30-50 body length/sec

1 µm

~2 m

13

2−∝∝ L

L

L

V

S

•  Limited everything on-board (actuation, power, computing, communication, sensing)

•  New design, fabrication and control methods

© Metin Sitti, MPI/CMU 10 cm 1 cm 1 mm 100 µm 10 µm

Our Miniature Mobile Robot Portfolio

4


Micron Scale Mobile Robots?

Challenge:

*M. Sitti, Nature 458, 1121, April 2009 (News & Views)

Miniaturization limitations on on-board power source & actuation*

© Metin Sitti, MPI/CMU On-Board Actuation Approach: Cell-Actuated (Self-Propelled)

Bio-Hybrid Micro-Robots •  Harvesting the motility of cells to actuate micro-systems •  Chemical energy inside the cell

Nature Comm. (2014)

Adv. Mat. (2014)

APL (2007), PNAS (2005), Biophys. J. (2004), …

R. Carlsen & M. Sitti, Small, on-line published (2014)

Nature Materials, 4 (2005)

5


Selected Bio-Actuator: Serratia Marcescens Bacterium

•  Speed: ~30 µm/s

•  Sticks to surfaces with their cell body

•  Chemotactic

Kwangshin Kim Science Photo Library Howard Berg

Harvard Univ.


Attaching Bacteria to a 10 µm Polystyrene Bead

Blotting on the culture plate

B. Behkam and M. Sitti, Appl. Phys. Lett., 90, 23902 (2007)

6


Bacteria Attachment Density Control

Attachment Time

Attachment Density

(Bacteria/µm2)

Sample Size

# of Bacteria on 10 µm bead

30 sec 0.17 1 54

1 min 0.35 ± 0.14 10 111 ± 45

5 min 0.47 ± 0.14 7 149 ± 44

10 µm 10 µm 10 µm

30 sec 1 min 5 min

Representative Images for different attachment times:


Stochastic 3D Bead Translation & Rotation

MD : rotational drag on the bead FD : translational drag on the bead Fb : bacteria propulsive force

Motion parameters: •  Flagella run and tumble rates •  Flagella propulsion force & torque •  Flagella hook flexibility & orientation •  Bacteria number & surface distribution •  Bead radius •  Neighboring flagella microfluidic coupling? •  Neighboring bacteria communication?

Hook

V. Arabagi, B. Behkam, E. Cheung, & M. Sitti, J. Appl. Phys. 109, 114702 (2011)

7


3D Motion Tracking from 2D Images using Light Diffraction

Calibration images


Different 3D Motion Patterns Near vs. Away From the Surface

Away from the glass slide Near the surface

5 micron beads

M. Edwards, R. Wright, & M. Sitti, Appl. Phys. Lett. 102(14), 143701 (2013)

Spiral motion of single bacterium attached beads away from surface: Bacterium torque/force measurement

8


Steering Control using Chemotaxis?

Chemoattractant (L-aspartate) Diffusion

Bacteria attached beads moving towards chemical attractant gradients?


Uniform Chemical Gradient Generation

9


Chemotactic Behavior of Unpatterned Beads

10 µm bead, 2.5x speed


2D Motion Trajectories No Chemoattractant Chemoattractant

Vmean = 1.8 ± 0.8 µm/s Vmean = 3.3 ± 1.3 µm/s

D. Kim et al. Biomedical Microdevices 14(6), 1009 (2012)

10


Active Steering Control using Remote Magnetic Fields

R. W. Carlsen, M. R. Edwards, J. Zhuang, C. Pacoret, & M. Sitti, Lab Chip 14(19), 3850 (2014)


Bacteria Propelled Swimming Micro-Robotic Swarms for Future Medical Applications?

Bacteria

Physical platform •! Environment sensing

•! Bacterial actuation

•!Chemotactic/magnetotactic control

Statistical physics computational model

•!Emergence and dynamics of dense networks of bacteria propelled micro-robotic swarms

•!Characterization of collective and competitive behavior

Targeted region

Micro-robotic swarm

Single micro-robot within a swarm

Dense networks of micro-robotic swarms

11


Off-Board Approach: External Actuation

Electrostatics Donald et al.,

Dartmouth College, USA (2005)

Scratch-drive

Nelson et al. (2009) Fischer, et al. (2009)!ETHZ Bacterial propulsion

Magnetics

Thermal Sul et al., U. North

Carolina, USA (2006)

Laser excitation 20 µm

100 µm

Yamakazi et al., Tohoku University, Japan (2001)3) Rotational swimmer

Nelson et al., ETHZ (2007) Inertial resonant drive


Why Magnetics?

•  Versatile and Robust –  No specialized surfaces

(vs. Electrostatic) –  Long range –  No specialized environments

(vs. dirt & humidity) –  No line of sight (vs. Optical)

•  Favorable to micron scale –  High (forces &) torques

Abbott et al., IEEE RAM 14 (2007)

12

© Metin Sitti, MPI/CMU Proposed Micro-Robot Motion Principle:

Rotational Stick-Slip Motion •  Robot body

–  Permanent magnet –  Arbitrary geometry

•  Pulsed magnetic fields –  Torque-based asymmetric

rocking inducing stick-slip –  Less than 1 mT sufficient

•  Works on complex surfaces •  Operates in liquid/air/vacuum

–  < 60 mm/s in air –  < 40 mm/s in water

C. Pawashe, S. Floyd, and M. Sitti, I. J. Robotics Research 28(8), 1077 (2009)

Mag-µBot

Horizontal coil (x)

Bottom coil (z)

z

x


Experimental Setup

Permanent magnet micro-robot

13


Modeling Mag-µBot Behavior in 2-D •  Forces

–  Ty: Magnetic torques (1s of µN) –  Dy: Damping torque (1s of µN) –  Ff: Friction Force (100s of nN) –  N: Normal Force (100s of nN) –  Fadh: Adhesion (100s of nN) –  mg: Weight (100s of nN) –  Fx, Fz: Magnetic forces (10s of nN) –  Lx, Lz: Damping force (1s of nN)

•  Objective –  Create a dynamic simulation –  Predict robot behavior –  Predict robot velocity

Side-‐View Free Body Diagram

Painlevé Paradox (1895)


Contact Manipulation in Liquids

4 mm 350 µm micro-robot

underwater, 1x realtime

14


Autonomous Two-Particle Assembly

C. Pawashe, E. Diller, S. Floyd, and M. Sitti, IEEE Trans. on Robotics 28(2), 467 (2012)

u Vision-based control

u  Iterative learning of the pushing distance

•  Star-bot on glass in

silicone oil (20 cSt) •  210 µm polymer

sphere •  7.5 µm error tolerance •  2x video speed


Fabrication and micro-robotic manipulation of cell-encapsulating hydrogels

15


Cell Laden Micro-Gel Assembly 1 mm

1 mm

(a) (b) (c) (d)

(e) (f) (g) (h)

(i) (j)

S. Tasoglu, E. Diller, S. Guven, M. Sitti & U. Demirci, Nature Communications 5 (2014)


Versatility of Micro-robotic Assembly

16


Three-Dimensional Micro-robotic Assembly


Spatially Coded Constructs for

Tissue Culturing

17


3-D Assembly using Untethered Micro-Grippers

E. Diller and M. Sitti, Advanced Functional Materials 24, 4397 (2014)


Non-Contact Manipulation

•  Fluid boundary layers generated by moving micro-robot –  Drag force applied to micro-objects from fluid (Reynolds number < 1)

50 µm polystyrene sphere silicone oil (20 cSt)

C. Pawashe, S. Floyd, and M. Sitti, IEEE Trans. Robotics 25(6), 1332 (2009)

Finite element modeling of fluid flow for a translating star-bot

18


Rolling Locomotion and Particle Transport

Z. Ye, E. Diller & M. Sitti, J. Appl. Phys.

112, 064912 (2012)


Non-Contact Cell Transport

Z. Ye & M. Sitti, Lab on a Chip, 14(13), 2177 (2014)

19


Non-Contact Motile Cell Transport


3D Locomotion: Microswimmers

20


Rotational Swimmer using Flexible Flagella }  Flexible straight tail + Magnetic body à

Rotational propulsion }  Simple to fabricate with many flagella

}  Body rotation à Passive bending of tails }  Multi-flagella à Extra propulsion

M

Ω

Z. Ye, S. Regnier, and M. Sitti, IEEE Trans. on Robotics 30(1), 3 (2014)


Flexible Body Undulation based Soft Microswimmer

m(x)

B

B

B

(a)

(b)

(c)

(d)

(e)camera

coils

workspace

x

y

z

E. Diller, J. Zhuang, G. Z. Lum, M. R. Edwards, & M. Sitti, Applied Physics Letters 104, 174101 (2014)

21


Multi-Robot Control


Micron Scale Multi-Robot Control

•  Fundamental problem: How to address each micro-robot locally using global magnetic fields?

22

© Metin Sitti, MPI/CMU Addressing Micro-Robot Teams

Remotely using Novel Magnetic Composites

E. Diller, S. Miyashita, M. Sitti, RSC Advances 2(9), 3850 (2012)

Five spinning micro-robots that could control the fluid flow locally

•  No specialized surfaces •  In any fluid or air •  Many magnetic states •  Works also in 3-D •  Scalable


Self-Organizing Magnetic Micro-Modules

S. Miyashita, E. Diller, & M. Sitti, Int. J. Rob. Res. 32(5), 591 (2013)

23


Summary

•  Bio-hybrid (bacteria-propelled) micro-robots –  Chemotactic/pH and remote magnetic steering –  Many future challenges towards a clinical use, but the smallest micro-

robotic devices so far

•  Magnetic micro-robots –  Sub-mm devices possible –  Current bioengineering applications –  Will be exploring their clinical use (< 1 mm access capability?)

•  Potential applications –  Medical diagnosis, therapy, and local drug delivery –  Single cell manipulation and surgery –  Desktop micro-manufacturing

magnetically- and bacteria-actuated mobile micro-robots · 2015. 10. 14. · micron scale mobile...

Documents