Magnetic Catheters: A Journey Across Orders and Scales

This thesis studies a subgroup of flexible instruments called catheters.
Catheters are sleek tubes navigated through the natural cavities of human body
to reach remote organs with minimum tissue damage. However, due to their
high mechanical compliance, catheters are challenging to steer once inside the
body. This limits their applicability to a narrow range of tasks, predominantly
in endovascular surgery. Dexterity of a catheter can be increased by integrating
into its structure coils or permanent magnets, which experience forces/torques
in external magnetic field. Such magnetic catheters are capable of exhibiting
complex mechanical behaviour, while being structurally simpler than comparable
devices. The following chapters demonstrate how, by using the principles of
robotics, this behaviour can be harnessed to execute clinically-relevant tasks.
Contributions are made in three general areas. The thesis proposes novel designs
of magnetic catheters, explores the means to sense and model their behaviour and
devises control strategies enabling their operation.