Master of Engineering Science
Mechanical and Materials Engineering
Price, Aaron D.
Trejos, Ana Luisa
Electroactive polymers are an emerging branch of smart materials that possess the capability to change shape in the presence of an electric field. Particularly, ferroelectrets are films of electrostatically charged dielectric polymer foam that comprise a growing portion of EAP literature. Ferroelectrets are characterized by a piezoelectric response and a quasi-permanent charge polarization owing to the dipoles created when the air cavities in the polymer matrix undergo dielectric breakdown. However, these cavities are often irregular in shape, size, and distribution when produced with conventional preparation methods. To overcome this, we employ a light-based additive manufacturing technique to create a hybrid photopolymer ferroelectret structure with regular and repeatable voids. Furthermore, we developed a high-voltage electrostatic poling apparatus that allows a precise and uniform charging of the engineered ferroelectrets. The stability and uniformity of the charge polarization and the piezoelectric performance of the hybrid photopolymer ferroelectrets are characterized to evaluate the suitability of this material in energy harvesting applications.
Summary for Lay Audience
Electroactive polymers are a family of plastics that convert mechanical deformation into electrical energy and vice versa. They are deployed in sensing, actuation, and energy harvesting applications. Ferroelectrets are an emerging class of electroactive polymers that consist of thin foam films. These foam films are characterized by closed-cell air voids of varying shapes and sizes in the bulk of the material. Since these films are comprised mostly of these air-filled cavities, ferroelectrets are typically low stiffness polymers. In this work, we use a light-based 3D printing approach to control the size and distribution of these voids. When a strong electric field is applied to the 3D printed films, the air inside the voids undergoes a dielectric breakdown, resulting in a micro-scale "lightning" phenomenon in these voids. This functionalizes the cavities, giving them the ability to transduce mechanical deformation into electrical signals. Once functionalization has been achieved using a custom-built charging apparatus, the performance of the engineered ferroelectret as an energy harvester is studied. It is envisaged that this proof of concept will be deployed in wearable applications.
Abu Shammeh, Rami, "Additive Manufacturing of Piezoelectric Photopolymer Ferroelectrets" (2019). Electronic Thesis and Dissertation Repository. 6838.
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