Actuators6

CONDUCTING POLYMER ACTUATORS

Pagilagan, Evan Mart P.

What is a Conducting polymer? Are organic polymers that conduct electricity. Generally not plastics. Can offer high electrical conductivity but do not

show mechanical properties as other commercially used polymers do.

The electrical properties can be fine-tuned using the methods of organic synthesis and by advanced dispersion techniques.

Types of Conducting Polymers

Ionic Conductive Actuator- soft, small, and lightweight.- is flexible, made of polymer and metallic materials.- low voltage requirement, only 2V.

The actuator element- motion can be controlled electrically.- soft as muscles.- light.- doesn’t generate sound upon operation.- Creation of the drive device from 0.1 mm to 10mm is

possible.- combination of element results in living thing like movement.

- Power consumption is able to move few for a long time.- Although it is driven in water fundamentally, a drive in air is also possible by the design of containing water.

In air operation. Robot Hand

Conducting Polymer Actuator- expand and shrink with doping and dedoping.- electrochemically driven for actuation.- polyacetylene, polypyrrole, polyphenylene, Polythiophene, Polyaniline, Poly(phenylene vinylene).

Polypyrrole (PPy)– conductive polymer- oxidation-reduction reaction when voltage is

applied- redox induces ion flow into or out of polymer- flow in = expansion- requires electrolyte

Performance for PPy bilayer actuator- strain: 12.4%- energy density: 0.040 J/g- speed: <1Hz - output pressure: 22 MPa- drive voltage: +/- 1V

“Wet” versus “Dry” actuation

“Wet” – Ionic actuators. Utilize mobility or diffusion of ions. polymer-metal composites conductive polymers others . . .

“Dry” – Electronic actuators. Utilize Coulomb forces. dielectric elastomers electrostrictive polymers others . . .

Electrostricted Polymers

Electrostricted graft elastomers motion achieved through electrostriction applied electric field induces a change from

one polarized direction to another, or one phase to another.

flexible backbone

polarized chain

Dielectric Elastomers

elastomer film is sandwiched between compliant electrodes

apply electric field: E = V/m Maxwell pressure: p = ee0E2

electrodes squeeze elastomer in thickness

V+apply voltage

Dielectric Elastomers

materials available off-the-shelf- 3M VHB acrylic tape- various silicone elastomers

desired features- high dielectric constant and breakdown strength- low elastic modulus – high % elongation- thin film

Dielectric Elastomers

Increase performance through prestrain- stretch elastomer film in one planar direction- fix motion in prestrained direction- allow expansion in other planar direction during

activation

V+

1 2 3 4

dielectric elastomer

electrode

rigid constraints

Dielectric Elastomers

Performance- strain: >200%- energy density: 0.75 – 3.4 J/cm3

- speed: 10Hz - 20kHz- output pressure: 3.0 – 7.2 MPa- drive voltage: 5kV

ACTUATOR COMPARISON

REFERENCES

http://en.wikipedia.org/wiki/Conductive_polymer

http://www.eamex.co.jp/tech_e.html http://www.eamex.co.jp/denshi_hp/

english/denshi_idex_e.htm web.me.com/daloy/LOY...Site/Polymer.../

conducting%20polymers.ppt www.cs.berkeley.edu/~jfc/DR/F03/

lectures/lec15/lec15.ppt