Selfsys

SELFSYS - Fluidic-mediated self-assembly for hybrid functional micro/nanosystems

Fluidic mediated self‐assembly for complex, hybrid micro/nanosystems

J. Brugger, A. Martinoli, N. Spencer, B. Nelson, H. Wolf, H. Knapp, L. Sciboz


Assembly challenge of N/MEMS

Today• Many different kinds of

micro/nano devices, MEMS, S&A, CMOS, OLED, etc

The challenge of tomorrow• Finding a way to assemble the

bricks into functional micro/nano-systems

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SoA for integrating multifunctional N/MEMS

• Co-integration (if possible)• Separate fabrication followed by joining• Wafer Bonding; Tape automatic bonding• Pick & Place; Robotic assembly

• Challenge for highly miniaturized systems• Challenge for very large numbers of components

• SELFSYS: Contribute with enabling manufacturing for future micro-assembly applications

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Fluidic mediated self-assembly

• Known concept in R&D• Using capillary forces to align components• At the interface of liquids• First industrial examples emerging

Srinivasan, Boehringer, U Washington, Seattle

LubricantHydrophobic area

Mastrangeli, van Hof, LambertIMEC, Belgium

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10 mm



MEMS

Surfaces

Microfluidic

Modelling

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Applications10 mm


SELFYS synapsis

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M/NEMS: J. Brugger (EPFL), Distributed systems: A. Martinoli (EPFL), Surface chemistry: N. Spencer (ETHZ), Nano-Robotics: B. Nelson (ETHZ), Microfluidics: H.

Knapp (CSEM), Self assembly: H. Wolf (IBM), RFID: L. Sciboz (icare Sion); add-on SELFSYS+: Ch: Hierold, D. Poulikakos (ETHZ)

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Maurizio Gullo

(EPFL)

V. Nagaiyanallur

(ETH

Z)

DidiXu

(ETH

Z)

Jonas Wiene

n(CSEM)

GMermou

d(EPFL)

LoicJacot‐De

scom

bes

(EPFL)

CathreinHü

ckstädt

(ETH

Z)

Deep

ak Kum

ar(ETH

Z)

M. M

astrangeli

(EPFL)


Progress within SELFYS

• MEMS part fabrication• Surface functionalization• In-liquid self-assembly experiments• Field induced assembly• Template induced assembly• Modeling

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Progress within SELFYS


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Investigated shapesShape:

Main material:

Expected advantages:

Expected disadvantages :

Scheme: Picture:

1Disc slices

SU‐8not restricted

to pairslow SA yield

2Flat

cylindersSU‐8

easy fabrication and handling

assembly possible on opposite side

3Rounded cylinders

SU‐8higher

pairing yield

4Half‐

spheresSU‐8 or

Ormocompeven higher yield in SA

smaller volume (cavity)

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Self-assembly of SU-8 cylinders

At water – Si oil interface: At water surface:

At the bottom: After water evaporated:

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Fabrication of SU-8 microcapsules


Fabrication of Bi-color SU-8 cylinders

SEM images of the cylinders before release (diameter ~ 100 um and height ~100 um)

Optical image of un‐specific assembled parts in DI water after stirring.


Surface functionality for specific assembly

Yield(assembled/total): ~ 65 %


Surface Modification of SU8

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Plasma treatment:

CA 70‐80 deg

CA < 10 deg


Photo-cleavable polymer layerCovalent grafting of any desired polymer onto SU‐8 can be achieved by this methodology.


Half-sphere shape by inkjetting

DAngle max at the edge: ν = CA + 180° ‐ ф

100 um


Adhesion force modulation

0.00E+00

2.00E+05

4.00E+05

6.00E+05

8.00E+05

1.00E+06

1.20E+06

1.40E+06

1.60E+06

‐60 ‐40 ‐20 0 20 40 60

Force

Alignment [um]

Calculated surface correlation:

RingGoalMulti ring E2

E1

dE

Srinivasan et al. 2001, J. Microelectromech. Syst. 10 17–24

40um

Microfabricatedcapsules

Materials investigated:Carbon coated tip/sampleTeflon (C4F8) coated tip/sampleAu coated + dodeca thiols (DDT) monolayer tip/sample R=2µm

SphereTip©


Force Curves / Teflon Coated Tip and Sample

Adhesion Force

retractivesnap out

DI water

Sample

Force Curve

parameter value

# curves 500

# positions 100

speed 0.5 Hz

rest time on sample 0.5 s

temperature 22°C

humidity 33%

tip

sample

teflon

movement

DI water

None or only very small and unstable attracting force could be observed for the Teflon coated tip and sample measurements


Forces between surfaces / summary

0.00E+00

2.00E+05

4.00E+05

6.00E+05

8.00E+05

1.00E+06

1.20E+06

1.40E+06

1.60E+06

‐60 ‐40 ‐20 0 20 40 60

Force

Alignment [um]

RingGoalMulti ring E2

E1

dE

Material Attraction Force Adhesion force

DDT 6e-6 nN/nm^2 3.8e-4 nN/nm^2

Carbon 3e-5 nN/nm^2 4e-4 nN/nm^2

Teflon 0 nN/nm^2 1e-4 nN/nm^2

Material E2 E1 dE

DDT 1.16 mN 0.29 mN 0.87 mN

Carbon 1.23 mN 0.31 mN 0.92 mN

Teflon 0.31 mN 0.08 mN 0.23 mN

•Hydrophobic interaction forces could be quantitatively assessed by AFM.

•Carbon and DDT show similar adhesion force.

•Carbon better suited for micro fabrication.


Progress within SELFSYS


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3 stage fluidic assembly system1. Preparation - Transfer of parts into

functional fluid2. Assembly - Agitation of particles to drive

self-assembly3. Sorting - Sorting out and transferring back

not correctly assembled partsSupply fluid cycle

Functional fluid cycle

Sedimentation filter

Reactionchamber

Sorter

Container for assembled parts


Reaction chamberChamber size: 1 cm diameterInlet and filtered outletPiezo-actuationChange in amplitude/frequencyShear forces at bubblesBubbles moving around

RC‐Core

US‐transducers

Glass unit(laser cut)

PDMS ‐Sealing

Filter within sealing

Outlet

Outlet (filtered)

Inlet




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Field assisted assemblyDielectrophoretic assisted assembly• RFID chips (mCHIP/Hitachi)

in liquid.• Micro-chips with unique

codes

Octomag motion of magnetic SU-8 flaps• Magnetic nanoparticle in

photo-patternable SU-8

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Multi-scale modeling

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Can we devise a unique methodological framework for modeling and controlling these self‐assembling systems, across length‐scales?

Robotic building blockTypical size: 2 centimetersTypical swarm size: a few dozen unitsActive units: sensing and actuationCapillary and magnetic forces»»Stochastic, fluidic control (pump)

MEMS building blockTypical size 50 to 500 umTypical swarm size: 10^2 to 10^3 unitsPassive units: only local interactions»»Hydrophobic forces»»Stochastic, fluidic control (piezo)

5cm ALICE robotSwarmPower to moveSimple on board intelligenceCollective behavior

2D 2D 3D


Modeling Distributed Systems

Microscopic 1: Monte Carlo model, 1 robot = 1 agent, non-spatial

Abs

trac

tion

Exp

erim

enta

l tim

e

Com

mon

met

rics

Microscopic 2: Agent-Based model, 1 robot = 1 agent, spatial

Macroscopic 2: Chemical Reaction Network, stochastic simulations

Macroscopic 1: rate equations, mean field approach, whole population

Define physical parameters suitable for simulation of distributed, self-organizing

(micro) systems

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Modeling / simulation

• 2-body motion / encounter

• 100-bodies

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Material Attraction Force Adhesion force

DDT 6e-6 nN/nm^2 3.8e-4 nN/nm^2

Carbon 3e-5 nN/nm^2 4e-4 nN/nm^2

Teflon 0 nN/nm^2 1e-4 nN/nm^2


• Magnetic particles embedded in SU-8*• DNA coating on microcapsules• Thermal modeling**• enhance control of assembly/separation

Add-on tasks SELFSYS+

T>Tm T<Tm T>TmB=onB=on B=off Mix=onMix=offMix=on

a) directionality b) selectivity c) reversibility

Para‐magneticcapsule

* add‐on partner Ch. Hierold** add‐on partner D. Poulikakos/J. Thome


Summary & Outlook

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100 um

MEMS Modeling Fluidic assembly system

Hollow capsulesControlled liquid‐release

T>Tm B=off Mix=on

opening

Capsule disassembly


M/NEMS: J. Brugger (EPFL), Distributed systems: A. Martinoli (EPFL), Surface chemistry: N. Spencer (ETHZ), Nano-Robotics: B. Nelson (ETHZ), Microfluidics: H.

Knapp (CSEM), Self assembly: H. Wolf (IBM), RFID: L. Sciboz (icare Sion); add-on SELFSYS+: Ch: Hierold, D. Poulikakos (ETHZ)

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Maurizio Gullo

(EPFL)

V. Nagaiyanallur

(ETH

Z)

DidiXu

(ETH

Z)

Jonas Wiene

n(CSEM)

GMermou

d(EPFL)

LoicJacot‐De

scom

bes

(EPFL)

CathreinHü

ckstädt

(ETH

Z)

Deep

ak Kum

ar(ETH

Z)

M. M

astrangeli

(EPFL)


Liquid release from micro-capsule

Self‐assembled Blue ink encapsulated Ink released

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Hollow SU-8 microcapsules

Side view

Top view

overflow13 drops…


Functionalization of SU-8 surface

PSS

PDDA

The charge characteristics are tested by dispersing SiO2 particles

Poly(diallyldimethylammonium chloride)(PDDA) – positively charged surfacePoly styrene sulfonate (PSS) – negatively charged surface


Microdrop printing of functional material

Luminescent NCsKim Small 2009

Printing on Hot‐SurfaceLee APL 2007

Bio‐PrintingPataky in prep

Polymer MicrolensesFakfouri MNS 2009


Inkjet set-up


Force Curves / Carbon Coated Tip and SampleAttraction Force

Adhesion Forceattractive snap in

retractivesnap out

DI water

Sample

Force Curve

parameter value

# curves 500

# positions 100

speed 0.5 Hz

rest time on sample 0.5 s

temperature 22°C

humidity 33%

tip

sample

carbon

movement

DI water


Force Curves / DDT Coated Tip and Sample

A

B

C A

B C

Adhesion Force

DI water DDT

DI water DDT

Displacement of DDT Rearrangement of DDT

Fresh tip / sample

Sung et al, Appl. Phys. A 81, 109–114 (2005)

DI water DDT


Modeling SA across scales

SelfSys Lily

~ m ~ cm


Summary

• Hollow MEMS fabrication• Surfaces: O2 plasma, polymer• In-liquid self-assembly experiments• Field induced assembly• Template induced assembly• Modeling

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antenna

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Date post:	26-May-2015
Category:	Technology
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