Catheter and spring element for contact force sensing

A spring element for a contact force sensing medical catheter, the spring element comprising:

• a first ring;
• a second ring spaced apart from the first ring, the second ring and the first ring coaxially aligned with a longitudinal axis of the spring element;
• a plurality of struts configured to elastically deform to moveably couple the first ring to the second ring, each of the plurality of struts connected to an adjacent strut by an interconnect configured to define a space between adjacent struts;
• and
• wherein the plurality of struts includes a plurality of interlocking features configured to limit the relative axial and radial displacement between the first ring and the second ring, each of the interlocking features formed in the first ring and engaging one of the plurality of struts adjacent to the first ring, formed in one of the plurality of struts adjacent to the second ring and engaging the second ring, or formed in one of the plurality of struts and engaging a strut adjacent to the one of the plurality of struts, each of the interlocking features including:
• a tab including a head portion and a neck portion extending from one of the first ring or the one of the plurality of struts;
• and
• an opening defined in one of the second ring, or another one of the plurality of struts adjacent to the one of the first ring or the one of the plurality of struts from which the tab extends, the opening configured to engage the tab, the opening including a wide region and a narrow region, wherein the wide region contains the head portion and is wider in a circumferential direction and longer in an axial direction than the head portion, wherein the narrow region is wider than the neck portion of the tab, the narrow region is narrower than the head portion of the tab, and wherein the narrow region is defined by two opposing surfaces substantially parallel to the neck portion.

A catheter adapted to measure a contact force, the catheter comprising:

• a proximal segment;
• a distal segment;
• a spring segment extending from the proximal segment to the distal segment, the spring segment configured to permit relative displacement between the distal segment and the proximal segment in response to an application of the force on the distal segment, the spring segment including:
• a spring element including:
• a first ring;
• a second ring spaced apart from the first ring, the second ring and the first ring coaxially aligned with a longitudinal axis of the spring element;
• and
• a plurality of struts configured to elastically deform, the plurality of struts elastically coupling the first ring to the second ring and configured to permit elastic, relative axial and radial displacement between the first ring and the second ring;
• wherein the plurality of struts includes a plurality of interlocking features configured to limit the relative axial and radial displacement between the first ring and the second ring, wherein each of the plurality of interlocking features is formed in a strut of the plurality of struts and interlocks with an adjacent strut of the plurality of struts;
• wherein the plurality of interlocking features includes:
• a tab including a head portion and a neck portion connecting the head portion to one of the first ring, the second ring, or one of the plurality of struts, the head portion being wider than the neck portion;
• and
• an opening including a wide region and a narrow region, wherein the wide region is wider in a circumferential direction and longer in an axial direction than the head portion, wherein the narrow region is wider than the neck portion of the tab, the narrow region is narrower than the head portion of the tab, and wherein the narrow region is defined by two opposing surfaces substantially parallel to the neck portion, the head portion of the tab contained within the wide region and the neck portion of the tab extending through the narrow region such that the opening engages the tab to limit the relative axial and radial displacement between the first ring and the second ring;
• and
• a plurality of sensing elements configured to output a plurality of signals indicative of the relative displacement between the proximal segment and the distal segment.