Date of Award


Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Engineering Mechanics (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Joshua Pearce

Advisor 2

Craig Friedrich

Committee Member 1

Patricia Heiden


Soft actuators have grown to be a topic of great scientific interest recently. As the fabrication of soft actuators with conventional microfabrication methods are tedious, expensive, and time consuming, employment of 3-D printing fabrication methods appears promising as they can simplify fabrication and reduce the production cost. Complex structures can be fabricated with 3-D printing such as helical coils can achieve actuation performances that otherwise would not be possible with simpler geometries. In this thesis development of soft magnetic helical coil actuators of iron-oxide embedded polydimethylsiloxane (PDMS) was achieved with embedded 3-D printing techniques. Composites with three different weight ratios of 10%, 20%, and 30% iron nanoparticles to PDMS were formulated. Using iron nanoparticles with 15-20nm size helps preserve viscosity of the printing material low enough that it was possible to print it with small gauge 29 needle (180 micrometers inner diameter). The hydrogel support of Pluroic f-127 bath and the ability to maintain the ratio of the printed fiber’s diameter to coil diameter close to 0.25 approximately resulted in the successful fabrication and release of fabricated helical coil structures. This enabled 3-D printed structures characterized as magnetic actuators to achieve linear and bending actuation of more than 300% and 80°respectively in the case of composites with 30% iron oxide nanoparticles. Moreover, it was shown that the 3D printed helical coils with 10% iron oxide nanoparticles can be utilized as an untethered soft robot that is capable of locomotion on 45 and 90 degrees inclines under an applied magnetic field.