ETD

• in-silico models
• intestinal actuation
• magnetic focusing
• magnetic nanoparticles

Intestinal dysmotility disorders are characterised by impaired or uncoordinated peristaltic activity and are associated with severe clinical consequences. Available treatments often provide only limited or short-term relief, as pharmacological and surgical interventions are hindered by systemic side effects, invasiveness, or poor efficacy, highlighting the need for alternative approaches.
This thesis investigates a novel strategy for partially or fully restoring physiological intestinal motility through magnetically induced mechanical stimulation, based on mucoadhesive magnetite nanoparticles applied to the intestinal wall and remotely actuated by a belt of permanent magnets, providing a minimally invasive means of generating localised peristaltic-like deformation. The fundamental components were assessed: porcine jejunum as the biological testing phantom, magnetite nanoparticles as the magneto-responsive materials, and neodymium magnets as external actuators. These elements were integrated in ex vivo experiments where bulge testing quantified physiological displacement and magnetic actuation demonstrated reproducible nanoparticle-mediated tissue deformation of the same order of magnitude as natural bulging. Building upon these findings, a finite element model was developed in COMSOL Multiphysics®, calibrated according to the experimental data, and subsequently extended to explore advanced magnetic configurations such as Halbach arrays, multi-layer arrangements, ferromagnetic flux concentrators, and paediatric scaling, providing predictive insights that identified effective field intensities in the range of 100–160 mT and guided the design of more focused and versatile magnet arrangements. A physical prototype integrating 3D-printed mechanical supports with stepper-motor actuation and Arduino-based control further validated the feasibility of coordinated magnet rotation and translation, merging mechanical and electronic subsystems into a single functional framework.
Overall, this work demonstrates the preliminary feasibility of magnetic stimulation for intestinal dysmotility, establishing a consistent link between experimental testing, numerical modelling, and system prototyping, and providing a robust basis for future developments including nanoparticle optimisation, wearable device design, and validation with synthetic phantoms replicating the intestinal wall, ultimately paving the way for the clinical use of magneto-responsive nanoparticles as actuators.