PolyMEMS: Plastics in Action - TU Dresden · polymer chemistry of TUD Research topics: Novel approaches of actuator-2 /18 based microsystems large-scale integration human machine

Faculty of Electrical and Computer Engineering Institute of Semiconductors and Microsystems

PolyMEMS:

Plastics in Action

Andreas Richter

18

Andreas Richter

Technische Universität Dresden

Institute of Semiconductors and Microsystems

Chair of Polymeric Microsystems

Dresden, 20 October 2010

1 /



⇒⇒⇒⇒ founded in March 2010

⇒ team of young scienists

Polymer synthesis µfluidics & energy sources

182 /

LSI systemsHuman machine confluence Unconventional computing

R. Luther S. Klatt

G. Paschew M. Fischer

R. Greiner

M. Allerdißen

M. Tietze

W. Haas





⇒ located at Andreas-Schubert-

Bau with the

polymer chemistry of TUD

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Bau with the


Research topics:

Novel approaches of actuator-

182 /


based microsystems

� large-scale integration

� human machine confluence

(virtual and augmented reality)

� unconventional computing

� microfluidics






Bau with the


Research topics:


182 /


based microsystems

� large-scale integration

� human machine confluence

(virtual and augmented reality)

� unconventional computing

� microfluidics

Presentation:

Microsystems based on smart

polymers


Intrinsically active polymers

Gel looper„Smart“ or intrinsically active polymers

⇒⇒⇒⇒ extraordinary and fascinating

properties

⇒ spectacular examples

⇒ Insider´s tip in the actuator community

However:

⇒ Technical sensor and actuator

183 /

Gong, J.-P. et al.

Hokkaido University, Sapporo

http://altair.sci.hokudai.ac.jp/g2/gelmachine4_e.html


applications of these materials are

very rare

What are smart polymers and which

properties do they have?


Intrinsically active polymers

Shape memory

polymerConductive

polymers

0V

„Smart“ or intrinsically active polymers

⇒⇒⇒⇒ extraordinary and fascinating

properties

⇒ spectacular examples

⇒ Insider´s tip in the actuator community

However:


183 /

Lendlein, A. et al.

Angew. Chem. 2002, 41, 2034

Smela, E. et al.

Sens. Act. B 2006, 115, 596

0V

-1VWell-known examples

⇒ shape memory polymers

⇒ conductive polymers

⇒ most suitable characteristics profiles

for microsystems applications:

stimuli-responsive hydrogels


applications of these materials are

very rare

What are smart polymers and which

properties do they have?


Stimuli-responsive hydrogels

… cross-linked plastic materials

- able to change their volume reversibly and

reproducible more than one order of

magnitude by small alterations of certain

environmental parameters

⇒ highest volume change of solid-state

materials

Ela

sti

cit

y

Range of phase transition

184 /

Reason: Volume phase transition behavior

Vo

lum

e,E

las

tic

ity

Physical Value (T, c, pH)


Stimuli-responsive hydrogels

… cross-linked plastic materials

- able to change their volume reversibly and

reproducible more than one order of

magnitude by small alterations of certain

environmental parameters

⇒ highest volume change of solid-state

materials

184 /

Reason: Volume phase transition behavior

Precondition:

Polymer is at a critical swelling equilibrium

⇒ appears in two phases

⇒ small impairments of the polymer-solution

interactions, e.g., by small changes of T

or c lead to a general change into the

second swelling equilibrium

Separated phase

Polymer-Polymer

interactions

⇒ as smallest volume

as possible

Mixed phase

Polymer-Solution

interactions

⇒ as biggest volume

as possible


Triggering factors of phase transition

Concentrations of solvents

- neutral hydrogels

10

12

14

16MethanolEthanol1-Propanol2-PropanolAceton

De

gre

e o

f s

we

llin

g

Poly(N-Isopropylacrylamide)

185 /

0 10 20 30 40 50 60 70 80 90 1000

2

4

6

8

Aceton

De

gre

e o

f s

we

llin

g

Solvent content in vol%




- neutral hydrogels

Concentrations of ions, pH value

- polyelectrolyte hydrogels

1,6

1,8

2,0

2,2

Fil

m t

hic

kn

es

s i

n µ

m

Polyvinyl alcohol – polyacrylic acid

185 /

0 2 4 6 8 10 12 14

1,2

1,4

1,6

Fil

m t

hic

kn

es

s i

n

pH value




- neutral hydrogels

Concentrations of ions, pH value

- polyelectrolyte hydrogels

Temperature 10

12

14

16

18

De

gre

e o

f s

we

llin

g

PNIPAAm

PVME

185 /

Temperature

- hydrogels with:

- LCST

- UCST (not really available)

0 10 20 30 40 50 600

2

4

6

8

10

Temperature in °C

De

gre

e o

f s

we

llin

g

PVME


Alterable properties

Optical properties

- refractive index

- transmission

- color


186 /

n,

Physical value (T, c, pH)

swollen: Refractive index = 1,36

shrunken:Refractive index = 1,46

Kuckling et al., Macromol. 2002, 35, 6377



Optical properties

- refractive index

- transmission

- color

Mechanical properties

- Young´s modulus

- softness


186 /

- softness

n,


swollen: E = 13 kPa

shrunken:E = 85kPa

E,



Optical properties

- refractive index

- transmission

- color

Mechanical properties

- Young´s modulus

- softness


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- softness

Size

- volume

- length, height n,


swollen: QV = 16

shrunken:QV = 2,1

E,V


Actuator properties

Muscle-like actuator type

- big volume change

- medium energy density

-3]

101

102

103

SMAMetall

Magn.Formge-dächtnis

Ac

tua

tor

str

en

gth

σσ σσm

ax

[MP

a]

Energy density [Jm -3]

101

102

10

SMAmetall

Hydrau-

licsMagn.

shape

memory

σσ σσ

Electrostriction

Therm. exp.10K

Magnetostriction

Therm. expansion100K

186 /

10-510-6 10-310-4 10-110-2 101110-2

10-1

1

Hydro-gele

dächtnis

Max. Strain εεεεmax

Ma

x. A

ctu

ato

r s

tre

ng

th

Piezo-LS

Piezo

10-510-6 10-310-4 10-110-2 101110-2

10-1

1

-

memory

Piezo

polymer

Piezo

LS

Pneumatics

Human

muscle

Solenoid

Hydro-gels


Actuator properties

Muscle-like actuator type

- big volume change

- medium energy density

Time behavior

- swelling is diffusion controlled

⇒ size dependent

1cm

Response time

min - hours

hours - days

186 /

⇒ size dependent

⇒ Centimeter size: response time

in h or days

⇒ Micro size: response time

in 100 ms range can be

obtained

1mm

1µm

200µm

-

1µm ms

100 ms – sec.

Microsystems


Hydrogel-based platform technology

Preconditions:

Fabrication technology

Mechanisms to control

active elements

187 /

active elements

Active elements

in microfluidics:

- micro pumps

- microvalves

- …


Micro structuring of hydrogels

Photo lithography

- dry films: UV crosslinking

- prepolymer solution:

UV polymerisation

⇒ monolithic microsystems

Microgel preparation

Photo lithography

UV crosslinking UV polymerisation

188 /

Microgel preparation

- Suspension, dispersion, emulsion

polymerisation

size: 20nm … mm

Further methods:

- Electron beam lithography

- moulding polymerisation

- plasma polymerisation

- …

100µm

50µm


Controllability

Electric controlScience 218 (1982), 467

⇒ ∆V = 90 %

… in 4 days !!

Control of hydrogel microactuators

189 /

Tanaka, T. et al., Science 218 (1982),467


Controllability


⇒ ∆V = 90 %

… in 4 days !!

Optical controlNature 346 (1990), 347

⇒ ∆


18

⇒ ∆V = 70 %

… limited reversibility !!

9 /

Tanaka, T. et al., Nature 346 (1990), 347


Heating meander

Channel

Controllability


⇒ ∆V = 90 %

… in 4 days !!

Optical controlNature 346 (1990), 347

⇒ ∆


18

Electrothermic interface

⇒ standard method of electronic control of

hydrogel actuators Gel actuator

Polym. Adv. Techn. 11 (2000), 496-505.

⇒ ∆V = 70 %

… limited reversibility !!

⇒⇒⇒⇒ microfluidic basic elements

9 /


Inlet Outlet

Problem:

Hydrogel absorbs liquid by swelling

⇒ no displacement of liquid

Microfluidic propulsion

18

Pump chamberHeating

meander

Lab Chip 9 (2009), 613

10 /


Inlet

Actuator

Elastic

Membrane

Heating element

FelastFquellProblem:



a) Diffusion micropump

• Actuator is placed within the

pump chamber

• Actuator loads the chamber with


18

Lab Chip 9 (2009), 613

liquid and stretches the elastic membrane

• Membrane pushes the liquid to the outlet

10 /


Inlet

Actuator

Elastic

Membrane

Heating element

FelastFquellProblem:





pump chamber



18

Lab Chip 9 (2009), 613



10 /


6

8

10

12

14

Vo

lum

e [

µl]

Peristaltic: 0,54µlmin-1

Pulsatile:

Long-time 1,2µlmin-1

1 Stroke 3,31µlmin-1

Problem:





pump chamber



18

Pumping pressure

• pmax = f (Felast) = 1,3kPa

0 2 4 6 8 10 120

2

4

6

Vo

lum

e [

µl]

Time [min]



Lab Chip 9 (2009), 613

10 /


Problem:




Inlet

Hydrogel actuator

Movable

membranePump chamber


pump chamber



18

Lab Chip 9 (2009), 613

b) Displacement micropump

•Due to the membrane the actuator

displaces the liquid

Pumping pressure

• pmax = f (Fswell) = 15kPa

Pump chamberHeating meander

Outlet

Actuator

chamber

Lab Chip 9 (2009), 613

Pumping pressure

• pmax = f (Felast) = 1,3kPa



10 /


Open

Heater

Actuator chamber

TH ≥ TPT Hydrogel

(shrunken)

Microvalves•Actuator directly placed within the channel

Principle

•Open valve: Heating the valve seat above

TPT

⇒ Hydrogel actuator shrinks

•Closing: switch-off the heater

⇒ below T the hydrogel actuator swells

Microfluidic switching

18

J. Microelectromech. Syst. 12 (2003), 748

(shrunken)

TH < TPT Hydrogel

(swollen)

Closed

Heater

⇒ below TPT the hydrogel actuator swells

11 /


20

25

30

35

20

25

30

35

Tem

pera

ture

in

°C

Flo

w in

µl/

min


Principle


TPT





18

J. Microelectromech. Syst. 12 (2003), 748

0 2 4 6 8 10 12 14 16 18 200

5

10

15

0

5

10

15

Tem

pera

ture

in

Flo

w in

µl/

min

Time in min

⇒ actuator absorbs the liquid during

swelling

⇒ valve closes displacement free

•Excellent properties

• Back pressure up to 8 bar

• Particle tolerance and leakage free

• Response time:

- opening: 300ms

- closing: 1s (uncooled)


11 /




Principle


TPT




18

Microscopy tool MicCell of GeSiM mbH containing 6

hydrogel microvalves

⇒ since 2004 commercialized by

GeSiM mbH11 /

⇒ actuator absorbs the liquid during

swelling

⇒ valve closes displacement free

•Excellent properties

• Back pressure up to 8 bar

• Particle tolerance and leakage free

• Response time:

- opening: 300ms

- closing: 1s (uncooled)



Microgravimetric pH sensor

•Changes in V, m and E of a

hydrogel-coating lead to a change

of the complex resonance frequency

of a quartz crystal

Chemical sensing

18

Sens. Actuat. B 99 (2004), 579

Sensors 8 (2008), 561

Time

∆∆ ∆∆z

12 /


Da

mp

ing

sh

ift

in k

Hz

Fre

qu

en

cy s

hif

t in

kH

z

15

20

25

30

15

20

25

30

⇒⇒⇒⇒ within the area of phase

transition the accuracy of

measurement is ± 0,042 pH units





of a quartz crystal

Chemical sensing

18

2.50 2.75 3.00 3.25 3.50

Da

mp

ing

sh

ift

in k

Hz

Fre

qu

en

cy s

hif

t in

kH

zpH value

0

5

10

0

5

10


Sens. Actuat. B 99 (2004), 579

Sensors 8 (2008), 561

12 /


1.5

2

2.5

Fre

qu

en

cy s

hif

t in

kH

z

pH 3.11pH 3.19








of a quartz crystal

Chemical sensing

18

0 50 100 150 2000

0.5

1

Fre

qu

en

cy s

hif

t in

kH

zTime in s

pH 1.84 pH 1.84

•Time behavior:

- Solutions with high ionic strength

tResponse = (500 … 800) ms

⇒ real-time measurements


Sens. Actuat. B 99 (2004), 579

Sensors 8 (2008), 561

12 /









of a quartz crystal

Chemical sensing

18

•Time behavior:

- Solutions with high ionic strength

tResponse = (500 … 800) ms

⇒ real-time measurements


12 /

⇒ commercialized by SITA Messtechnik

GmbH

Dresdner Transferbrief 01/2010, 8


1mm

•Control device to regulate a concentration

•Design similar to microvalves

• hydrogel acts as both sensor and actuator

Chemical transistor

18

Adv. Mater. 19 (2007), 1109

Inlet

Outlet

T-Sensor

Heater

Hydrogel

Fabricated by GeSiM

1mm

Sens. Actuat. B 125 (2007), 569

13 /





• Transistor characteristics:

- opens if the threshold concentration is

reached50

60

70

µl/

min

]

Transistor characteristics

Regulation of a methanol

concentration in H2O (27°C)

Chemical transistor

18

- closes below the threshold concentration

13 /

2 3 4 5 6 7 8-10

0

10

20

30

40

50

Flo

w r

ate

[µ

l/m

in

cMetOH [mol/l]

cThreshold


26

30

34

co

ntr

ol[°

C]

Methanol Ethanol

1-Propanol




• Transistor characteristics:

- opens if the threshold concentration is

reached

Chemical transistor

18

0 2 4 6 8 10 12

14

18

22

Tco

ntr

ol

cAlcohol [mol/l]

Adv. Mater. 19 (2007), 1109

⇒Threshold concentration is adjustable

by control the temperature of the

hydrogel actuator

⇒ different from the fixed threshold of

electronic transistors

⇒ precondition of broad practical use

13 /

- closes below the threshold concentration


Actuator elements

Pumps Valves

Lab Chip 9 (2009), 613 J. Microelectromech. Syst.

• hydrogel-based platform offers a unique

range of active microfluidic elements

Intermediate conclusion

18

Chem. Sensors

Chemical

transistors

Sens. Actuat. B 99 (2004), 579 Adv. Mater. 19 (2007), 1109


12 (2003) 5, 748

14 /


Actuator elements

Pumps Valves




But what is the potential to realize

integrated microsystems?

⇒ new features ?


18

Chem. Sensors

Hydrodynamic

transistors



12 (2003) 5, 748

⇒ new features ?

⇒ can be solved big challenges?

14 /


Actuator elements

Pumps Valves






⇒ new features ?


18

Chem. Sensors

Hydrodynamic

transistors



12 (2003) 5, 748

⇒ new features ?


Of particular interest are:

• Medium-scale integrated (MSI) systems

(10-100 active components)

•Large-scale integrated (LSI) systems

(>100-10.000 active components)

14 /


Actuator elements

Pumps Valves






⇒ new features ?


18

Chem. Sensors

Hydrodynamic

transistors



12 (2003) 5, 748

⇒ new features ?


Of particular interest are:

• Medium-scale integrated (MSI) systems

(10-100 active components)

•Large-scale integrated (LSI) systems

(>100-10.000 active components)

⇒⇒⇒⇒ a LS system integration will be introduced

by an example outside the microfluidics

14 /


Infrared image of a resistive heater on

Polymer substrate


Problem:

If dS < dcritical

⇒ than the functionality of the neighbor

component can be affected

Question: Is the electrothermic control

suitable to realize small spacings between the

Actuator

Large-scale system integration

18

RHeat

15 /


active components?

1mm

ds

ds – Spacing between two hydrogel

components


swollenshrunken


Problem: If the

If dS < dcritical

⇒ than the functionality of the neighbor

component can be affected

Question: Is the electrothermic control



18

• to switch a hydrogel actuator from the fully

swollen state to fully shrunken ⇒ ∆T = 6K

Temperature [°C]

10 20 30 40 50 600

4

8

12

16

Sw

ell

ing

de

gre

e

Adv. Mater. 21 (2009), 979

• active cooling

⇒ dissipates excess heat and keeps the

controlling temperature field stable

⇒ independency from the environment

15 /


active components?


Time behavior


• light-induced T-field controlled by

a business video projection system

⇒ black substrate converts the absorbed light

into heat and transmits it directly to the

actuators


18

Adv. Mater. 21 (2009), 979

15 /


• T-field occurs nearly in real-time

Time behavior






actuators


18


t = 400ms

• stable for a desired period of time

Adv. Mater. 21 (2009), 979

15 /


33

34

35

36

Tem

pera

ture

[°C

]

xA2

x = 6

K• T-field occurs nearly in real-time

Time behavior






actuators


18

100 300 500 700 900 110013001500170028

29

30

31

32

Tem

pera

ture

[Distance [µm]

xRes

xA1

xP

∆∆ ∆∆T

Wo

rk

∆∆ ∆∆T

= 6

K

xP = xRes + xA1 + xA2

Pitch

Actuator sizeResolution

Obtained maximum parameters:

DA = 566 A cm-2

xP = 420 µm Adv. Mater. 21 (2009), 979

15 /


t = 400ms

• stable for a desired period of time


Imaging system with

• 4.320 (60x72) actuator pixels

• DA = 297 components per cm²

Intermodal Imaging system

18

Adv. Mater. 21 (2009), 979

16 /


• intermodal functionalities

visual:

Transmission light modulator

⇒ Monochrome display

Imaging system with




18

Adv. Mater. 21 (2009), 979

16 /



visual:



Imaging system with




18

Adv. Mater. 21 (2009), 979

16 /

tactile:

Multimodal modulators

⇒ intermodal display providing

impressions about

⇒ Softness of surfaces

∆E ≈ 70kPa



visual:



Imaging system with




18

Adv. Mater. 21 (2009), 979

16 /

tactile:



impressions about


∆E ≈ 70kPa

⇒ Outlines



visual:



Imaging system with




18

Knobs

Adv. Mater. 21 (2009), 979

16 /

tactile:


⇒ Outlines


impressions about


∆E ≈ 70kPa

⇒ Profils and Textures

∆l = 250µm


Virtual and augmented reality

Haptic touchpad• free programmable keypad

⇒ smart phones

⇒ tablet PCs

⇒ operating consoles

1817 /


Virtual and augmented reality

Haptic touchpad• free programmable keypad

⇒ smart phones

⇒ tablet PCs

⇒ operating consoles

3D- Percept-System

1817 /

3D- Percept-System• convey the impression,

⇒ to see a virtual object really

and

⇒ touch it and feel it with bare

hands as if it was the real

three-dimensional object


Thank you for your

attention !

18

attention !

18 /

Documents

PolyMEMS: Plastics in Action - TU Dresden · polymer chemistry of TUD Research topics: Novel approaches of actuator-2 /18 based microsystems large-scale integration human machine