Fistulas are an abnormal connection formed between two hollow organs or an organ and the skin that allow for the passage of fluids and other material. They are typically a surgical complication, however they can also form with Inflammatory Bowel Disease (IBD), cancer, and radiation therapy. Fistulas are difficult to manage and the only reliable treatment method is an invasive surgical resection. Unfortunately, many of these patients are far too sick to undergo such a procedure and face further complications such as infection, sepsis and death. Some patients heal spontaneously with gut rest and antibiotics, however the likelihood of this is difficult to predict.

The goal of this dissertation was to better predict those patients who would heal spontaneously as well as to characterize the geometry of enterocutaneous fistulas such that a better device for repairing the fistulas could be created. With this information, a fistula occlusion device was designed using a solenoid to control the placement of a glue plug.

The fistula occlusion device was broken down by component:​ the solenoid-based catheter and the electromagnetic glue. Cyanoacrylate is an adhesive that has been well-tolerated by the skin. Used internally, however, its low viscosity can cause the glue to flow past its intended location. Ferrofluids are a suspension of ferrous nanoparticles in a carrier liquid, typically oil or water. Under the presence of a magnetic field they can change their material properties. Previously, they have been combined with other liquids to be used as a control mechanism. Here, the goal was to combine ferrofluid with cyanoacrylate to create a glue that could be controlled with a magnetic field. The formulations of ferrofluid and cyanoacrylate analyzed here were shown to be incompatible as a glue product for two reasons:​ one- the cyanoacrylate cured too quickly to be used once combined, and two- the ferrofluid did not stay in solution with the presence of a magnetic field. This conclusion led to the solenoid-based catheter component of the device being re-evaluated for alternative applications.

The solenoid-based catheter was able to fulfill its design requirement of simultaneously passing fluid to a distal location and applying a magnetic field. Without the glue, the device needed a new application. Three potential applications were preliminarily studied:​ metallic foreign body (MFB) removal, targeted drug delivery, and tissue hyperthermia. MFB removal and targeted drug delivery both utilized DC power as the device was designed, while tissue hyperthermia required converting DC to AC in order to spin the particles in the ferrofluid and create heat. All three applications demonstrated suitability for the device. Further investigation and refinement is needed in order to tailor the device to a new, specific application.

This dissertation is unique in that it is focused on design-driven research in comparison to hypothesis-driven research. This approach, and its role in doctoral education, is outlined as a guidance for other programs considering adopting medical device design into their Ph.D. programs. Although the device will likely not fulfill the original intended use of occluding fistulas, it does have potential to provide a unique way of controlling ferrofluids in vivo.