Research

Patchy Particles   •    Particles at Interfaces   •    Field Assembly   •    Dye-sensitized Solar Cells   •    Electroactive Polymers   •    Swimmers   •    Metamaterials   •    Particle Films   •    Surface Modification   •    Three-dimensional Assembly   •    Particles as Templates

Dielectric Elastomers

Dielectric elastomers (DEs) respond to an electric field by changing their shape due to electrostatic attraction within the elastomer. Because they are flexible, affordable, and easily-fabricated, they are good candidates for electro-mechanical actuators. Based on the mechanism of DEs, electro-mechanical actuators can convert between electrical energy and mechanical energy which can employed into energy harvesting which the power is generated by the deformation of the generators due to the external force, or braille displays which the actuators deform to compress or bend due to addition electrical energy.

Figure 1. Maxwell effected EAPs.


Orientation and Alignment of Janus Particles in DC E-field

Silica particles carry a slight negative charge on their surface when immersed in an aqueous electrolyte and as a result they responded to an electric field. In our studies, we have modified silica particles with a neutral thin gold layer on one hemisphere. Due to the discontinuous surface charge, these modified silica Janus particles can be aligned in an E-field when dispersed in a dielectric elastomer, resulting in the generation of a highly localized dipole moment that efficiently enhances the overall dielectric constant of the material. The p(EGPEA) actuators with aligned Janus particles have higher dielectric constants which performs a high compressive strain when an external electric field is applied. It helps to reduce the operation voltage of electro-mechanical actuators.

Figure 2. The alignment of Janus Particles within DEs



Students:
Current Graduate Students: Hsin-yu Chen
Collaborators:

Posters:

Relevant Literature:
[1]H. Chen, A. J. Maliakal, and I. Kretzschmar, “Janus-particle Enhanced Electroactive Polymer Films” Proc. SPIE 8340, 2012, 83402W
[2]Bar-Cohen, “Electroactive Polymer (EAP) Actuators as Artificial Muscles: reality, potential, and challenges” 2nd ed, 2004

Funding:
• This work was supported in part by NSF-CBET (CAREER) 0644789