Self-assembling magnetic chains for minimally-invasive surgery

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Date
2022-06-13
Authors
Fass, Tim H.
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University College Cork
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Abstract
Minimally-invasive surgery has led to significantly improved success rates and decreased recovery times for surgical procedures, by minimising the access wounds to the patient. This imposes a restriction on any tool used during minimally-invasive surgery. A trade-off between incision size and the number of tools or tool size has to be achieved. The development of tools that change their shape, are able to pass through narrow ports and can assemble into functional forms is therefore desirable. This would decouple the size of the tool during use from the size during deployment. Such reconfiguring tools can be categorised under the engineering field of self-assembly, a process with countless examples in nature. The principle of self-assembly applied to surgical tools could potentially remove the size limitation a port imposes on the used tool. This work seeks to work toward the development of a general concept of self-assembly to be used in minimally-invasive surgery. The concept proposed in this thesis employs a subcategory of self-assembly, the self-folding chain. The self-folding chains analysed and proposed in this work mimic the process of the protein biosynthesis as it happens on a molecular level in our cells. A chain of magnetic components, linked together by rotational joints, allows for deployment through a long flexible tube and therefore facilitates the application in a range of surgical procedures. Once deployed and free of the confinement of the deployment tube, the magnetic attraction between the chain components in combination with the unique restrictions of the joints cause the chain to fold on itself to a functional device. Folding was first investigated in a plane where it could be recorded and analysed. The experimental results were tested against simulation and evaluated for their reliability and repeatability. Based on the results, a three-dimensional concept was developed. This concept allows for a uniform magnetic orientation of the folded device and consequently promotes the utilisation of the magnetic properties in surgery. Based on these properties, target applications were chosen in magnetic anastomosis creation and magnetic anchoring. The target scale necessary for use in minimally-invasive surgery places a range of challenges on material and mechanisms used. A prototype of a folding magnetic anastomosis device, which solves the need for an intelligent design of a compliant mechanism, was developed and tested in a pre-clinical study, demonstrating the feasibility of the concept.
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Self-assembly , Minimally invasive surgery , Chain dynamics
Citation
Hass, T. H. 2022. Self-assembling magnetic chains for minimally-invasive surgery. PhD Thesis, University College Cork.