Trasduttori Polimerici IPMC-Ionic Polymer Metal Composite IP2C

Trasduttori Polimerici
IPMC-Ionic Polymer Metal Composite
IP2C -Ionic Polymer -Polymer Composite
Ing. Elena Umana
Cosa sono gli IPMC?
La realizzazione di dispositivi di interesse in ambiti quale la
robotica, le applicazioni aerospaziali, la protezione civile e la
medicina richiede la sintesi e lo studio di nuovi materiali utilizzabili
come sensori e attuatori.
Gli Ionic Polymer Metal Composites (IPMCs) sono:
 materiali innovativi a basso costo
 morbidi e leggeri;
 sono biocompatibili;
 presentano
interessanti
fenomi
di
conversione
elettromeccanica, quindi possono essere usati nella
realizzazione di attuatori di movimento a bassa tensione di
alimentazione (muscoli artificiali) o come sensori di
movimento (è possibile la realizzazione di materiali
intelligenti con proprietà di sensing e attuazione).
Cosa sono gli IPMC?
IP Ionic Polimer: Perfluorinate Ionic-Exchange Membrane
Nafion#117® (DuPont ®)
[ -( CF2 - CF2 ) n – ( CF - CF2 ) m -]

O -CF - CF2 - O - CF2
-SO-3 …M+

CF3
ione positivo (catione)
Ione libero: H+, Li+, Na+
M Metal: Platino (generalmente) depositato
su entrambe le superfici
C Composite
Gruppo fisso
Come sono fatti gli IPMC?
Problemi attuali:
 problemi legati ai processi produttivi;
mancano dimostratori in applicazioni reali.
Processo di fabbricazione
Si deposita sul Nafion® un sottile strato
metallico in tre fasi:
1. scambio ionico tra gli ioni idrogeno e gli
ioni platino;
2. riduzione;
3. diffusione degli ioni che hanno un numero
di idratazione più alto rispetto al singolo
idrogeno (ioni sodio Na+, ioni litio Li+, etc.)
From IPMC to IP2C
Actuators
IPMCs tranduce an applied
voltage signal (along with the
corresponding
absorbed
current) into a deflection
and/or a force.
From IPMC to IP2C
Sensors
A
bending
deformation
produces charges migration and
hence a voltage signal that can
be suitably collected.
From IPMC to IP2C
Models have been developed for IPMCs by using the EuleroBernoulli theory for the beam in cantilever configuration.
i
3d t wY
s

4 Ls
f 1
3 Y d t2 L

I C sL  Lt  Lclamp 4 Ls
s
c
F
A=wt
x
t



2
3d Ls
 1
1


Lt 4

I C s  Ld  Lclamp wt
2 12 Ld 

1
s

 4Yt 2

z






w
2
3 d t Y 1
s

4 Ls Lt  Lclamp 1  s1 
v
From IPMC to IP2C
IPMCs suffer for a number of drawbacks: 1) The realization of electrodes
via noble metals is expensive because of used materials and requires a
time consuming chemical deposition technique.
IP2C have been introduced, by researchers in this working group, that uses
conducting polymers. They are:
•cheap;
•easier to be deposited;
•suitable for all-polymeric device realization.
From IPMC to IP2C
Basic procedure to fabricate IP2Cs:
1.
Sandblasting
2.
Chemical cleaning with solvent or ionic liquid used
3.
Organic conductor deposition through coating techniques
Spin coating
Drop casting
Dip coating
Solvent
Evaporation
Manufacturing procedure easier, faster and cheaper
From IPMC to IP2C
Used conducting polymers are:
Conductivity [S/cm]
Materials
10-2
10-1
100
101
102
103
104
105
106
Pedot:PSS
Pani
Poly-Pirrole
Fe, Au, Cu, Ag
SEM images of IP2C membranes
Cross-Section View
6.236μm
Tilted View
PEDOT:PS
S
PEDOT:PS
S
NAFION
Organic Conductor
Trade Name
PEDOT:PSS
CLEVIOS ® PH 500
PEDOT:PSS
CLEVIOS ® P HC V4
PEDOT:PSS
CLEVIOS ® PH 510
PEDOT:PSS
ORGACON™ EL-P 3040
NAFION
PANI
Polyaniline
From IPMC to IP2C
IPMCs suffer for a number of drawbacks: 2) as actuators their performance
is strongly depending on the quantity of solvent (generally water) and this
leaves the device very quickly. Liquids with high molecular weight or ionic
liquids have been proposed to alleviate such problem. We used the same
approach for IP2C, obtaining devices with very long lasting times in air.
Different solvents used inside Nafion®
membranes
Solvent
Deionized water
Solvent
Ethylene Glycol
Ionic Liquid
EmI Tf
5
0
-5
0
5
10
15
20
25
30
0
5
10
15
20
25
30
0
5
10
15
20
25
30
0.5
0
-0.5
Deformation (mm)
Absorbed Current (A)
Actuator measurements
Input Voltage (V)
From IPMC to IP2C
7
6
5
4
GPIB
interface
DAQ
Blocking Force (N)
Sensor measurements
Waveform
Generator
Displacement (mm)
s
1
0
-1
0
5
10
15
20
25
30
35
40
0
5
10
15
20
25
30
35
40
0
5
10
15
20
s
25
30
35
40
0.02
Laser Proximity
Sensor
f(t)
Load Cell
0
d(t)
Mechanical Vibration Generator
i(t)
IP2C
Current Amplifier
Sensing Current (A)
-0.02
5
0
-5
From IPMC to IP2C
Also for the case of IP2C models have been tested against
experimental data. The actuator….
From IPMC to IP2C
…and the sensor
Bode plot of experimental and
modeled sensing transfer function
Experimental
Predicted
Magnitude [dB]
0
-20
-40
-60
-80
-100
-1
10
0
10
10
Frequency [Hz]
1
Predicted
Experimental
Power Spectrum Magnitude [dB]
20
-100
-150
-200
2
10
200
Experimental
Predicted
Phase [deg]
0
-1
10
0
1
10
10
2
10
Power spectral density of experimental
and predicted current signals
-100
-200
-250
Frequency [Hz]
100
-1
10
0
10
10
Frequency [Hz]
1
2
10
Applications
A motor with smoth motion (I)
Applications
A motor with smoth motion (II)
Applications
A robot with a bioinspired motion control system
Applications
Biomedical applications
Applications
Biomedical applications
Applications
Time domain
Resonant vibrating probe:
Frequency domain
Applications
Robotic applications
Applications
And systems for energy harvesting.
Confronto Potenza W2,EMI1,EG3,W1 e W1dry
-8
10
-10
Power Magnitude[W/mm 2]
10
EG3 (Glicole Etilene - PHCV4)
EMI1 (EMI-Tf - PHCV4)
W2 (Acqua - PHCV4)
W1 (Acqua - Platino)
W1dry (Acqua - Platino)
-12
10
-14
10
1
2
10
10
Frequency [Hz]