Concentric Tube-Inspired Magnetic Reconfiguration of Variable Stiffness Catheters for Needle Guidance

Guiding catheters assist in delivering hazardous equipment such as needles through non-solid mediums likecavities and vasculature. Traditionally, metallic needles are passed through metallic guiding catheters, which are limited to linear paths or require anatomy-specific designs. Recently, variable stiffnessactive guiding catheters (AGCs) made of shape memory polymers have been developed. These AGCs can adapt to anatomy and guide equipment in their rubber and glass phases, respectively. However, passing needles can cause deflectionof the AGC and misalignment with the target. To address this, magnetic configuration of AGCs based on concentric-tube models is proposed to compensate for needle-induced AGC deflection. Experiments demonstrate shape configuration of AGCs using magnetic fields computed pre-experimentally, followed by needle guidance to three different targets. The results show AGC deflection of up to
$69^\circ$
and needle-induced backward deflection up to
$39^\circ$
, with a maximum target misalignment of
$4^\circ$
.