Date of Award


Document Type

Campus Access Master's Thesis

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Parisa Pour Shahid Saeed Abadi

Committee Member 1

Fei Long

Committee Member 2

Patricia Heiden


Actuators are widely used in many medical devices for a variety of surgical purposes. These actuators are also applicable in many prosthetic devices, and they are fabricated in a range of sizes depending on their usage. Also, they have different types of actuating mechanisms. Here, we investigate an electrochemical mechanism for an actuator for potential use in medical devices, and this mechanism is achieved using a nanocomposite. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is used as the polymer matrix with carbon nanotubes (CNTs) as a nanomaterial additive. This PEDOT:PSS and CNTs nanocomposite is used to 3D print filaments, which are then characterized for electrochemical and mechanical properties.

The ink was prepared by mixing aqueous PEDOT:PSS solution with CNTs. CNTs were first mixed with a surfactant - Triton X-100 - for dispersion by ultrasonication with a probe-sonicator. Also, dimethyl sulfoxide was added to PEDOT:PSS to give the solution a gel-like texture. The ink was loaded in a syringe, attached to the 3D printer, and filaments were printed at different pressures and speeds.

To evaluate the electrical and structural properties, characterization tests were performed. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to obtain capacitance and resistance of the printed filaments. Furthermore, linear actuation tests were performed to determine the strain developed in the printed filaments. Voltage ranging from -1.2V to 1.2V was passed through the filaments immersed in an electrolytic solution for all the tests. A 0.5 mN of force was applied for the linear actuation tests in the filament.

The study showed the significance of printing conditions, especially printing speed, in the specific capacitance of the printed filaments, likely due to the alignment of CNTs in the printing direction. Another influential factor was the width of the printed filaments. Thinner filaments appeared to have higher specific capacitance and lower values of impedance multiplied by surface area/mass. A larger portion of CNTs in thinner filaments is influenced by the shear forces applied by the nozzle, which is likely the reason for the effect of filament width. This work could serve as a guideline for fabricating capacitors and actuators with better performance for a wide range of applications.

Available for download on Tuesday, April 01, 2025