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FEEDBACK CONTROL OF A FEEDBACK CONTROL OF A

MICRO MANIPULATORMICRO MANIPULATOR

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On 3 stages:

Total displacement = 25mm (coarse / micrometer) 300300m (fine / PZT)m (fine / PZT)

Resolution = 100nm100nm (Joystick)

knob

Z

yx

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PZT flexurePipette (8m diameter)

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Application of the micro-manipulator

Micro-injection (ICSI )Micro-injection (ICSI ) Micro-dissectionMicro-dissection

Zona penetration

Zona

Taking out the dissected membrane

Zona Penetration

Sperm injection

Capturing the X chromosome

Dissecting

Taking the dissected part out

Storing the dissected chromosome

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MOTIVATION

• Motion Control of the tip

100nm is not enough for many sub-micron biological applications

• Dynamic Modeling

The uncertainties are causing very low success rates in biological applications

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PiezzoDrill control

Manipulator control

Current

Feedback

CURRENT SETUPCURRENT SETUP

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Control card

ROBUST CONTROLLOGIC F

eedb

ack

Control signal

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Present work

• Analyical model of the manipulator (excluding the pipette).

• Experimental set-up and tests on the same .

• Comparison of the experimental and analytical results.

• Experiments (including the pipette) with Hg in the pipette and without.

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Dynamic model

M2

X2

M1

X1

F

Spring (Ki)

Damper (Ci)

PZT force (F)

Equivalent mass (Mi)

F

M3

X3

Input : F; measured output X3

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0 0.002 0.004 0.006 0.008 0.01-1.5

-1

-0.5

0

0.5

1

1.5

Time (sec)

Dis

plac

emen

t (u

m)

X3 displacement comparison (the experiments vs. dynamic model)

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0 0.5 1 1.5 2 2.5

x 104

0

0.005

0.01

0.015

0.02

0.025

Frequency (Hz)

Dis

plac

emen

t(um

)FFT comparison (the experiments vs. dynamic model)

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TipPhotonic probePhotonic probe

Nano level displacement measurement setup

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Working principle of photonic probe

Light source

Ou

tpu

t (V

)

Distance (m)

Probe to target

distance

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Resolution = 2.5nmResolution = 2.5nm

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Experimental procedure

Photonic sensorGap

Read out (V)

5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Vol

tage

Time

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0 1 2 3 4 5 6-150

-100

-50

0

50

100

Time (sec)

Dis

plac

emen

t (nm

)Joystick control

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Setup for ICSI experiment without Mercurywithout Mercury

Vol

tage

Time

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Read out (V)

Pipette dia. < 8

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Setup for ICSI experiment with Mercurywith Mercury

Vol

tage

Time

MercuryMercuryMercuryMercuryMercuryMercuryMercury

Read out (V)

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0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.02

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

Time (sec)

X3 D

ispl

acem

ent (

um) without mercury

with mercury

X3 displacement comparison

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0 0.5 1 1.5 2 2.5

x 104

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

Frequency (Hz)

Dis

plac

emen

t (um

)

without mercury

with mercury

FFT comparison

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Observations

• The key is at the micro-dynamics of the pipette tip.• The pipette holder does not feel the presence of Hg. • Robust control is possible at 10nm of resolution

Obstacles

• Extreme flexibility at the tip (glass acts like fiber). • Displacement sensing (in 2-D) at the pipette tip• Complex visco-elastic interface between the Hg and

the pipette.

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