Session: 03-07-01: Innovative Product Design and Manufacturing

Paper Number: 113295

113295 - Design and Development of Shape Memory Polymer-Based Mechanical Thrombectomy Device 

In the biomedical industry, research and application of SMP have mainly been focused on drug-delivery implants, stents, orthopedic devices, tissue engineering, and wound closure. Little focus has been given to using SMP as delivery catheters or access devices. Most shape memory polymers today undergo a dual shape memory effect (SME) or one-way activation, where the polymer will change from a temporary shape back to a permanent shape. However, recent advances have seen the emergence of triple SME polymers with two different transition temperatures allowing for two temporary shapes before recovering to a permanent shape. For an SMP to have a suitable shape memory effect, the polymer network must have some form of cross-linking. Crosslinking gives the SMP a memory effect and enables it to recover its original shape without plastic deformation. There are two types of crosslinked SMP, chemically crosslinked SMPs and physically crosslinked SMPs. Chemical crosslinking can be described as any crosslinking that occurs as a result of covalent bonding that forms between the molecules, such as epoxy or methacrylate networks. Physical crosslinking can be described as physical interactions such as hydrogen bonding, phase separation or any physical entanglement that forms links between the molecules. This work aims at designing and developing a proof-of-concept thrombectomy device, using an SMP at the distal tip of a microcatheter, which would recover to a desired shape to act as a retrieval mechanism, removing a thrombus from an occluded artery in an acute ischemic stroke. The catheter was built using a PTFE liner substrate, braided reinforcement, a Pebax jacket layer, and a coiled copper wire heating element. A shape memory polyurethane (SMPU) was extruded and reflowed over the copper coil. The SMPU was shape-set into a helical shape and was then formed into a temporary straight shape. Thermomechanical testing of the SMPU demonstrated the effect of temperature on the mechanical properties, as when the polymer was heated above the transition temperatures of 70°C and 140°C, the mechanical behaviour changed, resulting in a lower stress but a greater strain rate. Applying a direct current to heat the copper coil and cause a thermal stimulus in the SMPU successfully induced a shape recovery of the distal tip to its original helical shape. Within this frame of reference, this work describes an SMPU tubing material with a straight secondary shape that can recover its coiled primary shape once thermally stimulated. The proof-of-concept further strengthens the experimental success.

Presenting Author: Rupal Srivastava Confirm Smart Manufacturing, TUS Athlone

Presenting Author Biography: Dr. Rupal Srivastava is a Marie Sklodowska Curie Fellow – co-fund SMART4.0 at the SFI Confirm Smart Manufacturing Centre, Ireland. She completed her Ph.D. in Solid Mechanics and Design at the Indian Institute of Technology- Kanpur, where she worked on Active Composites and Smart Materials. Currently, she is working on Memory Alloys and their integration with Smart Wearables, the Digital Twin of a Manufacturing Pilot Line, and as an investigator on the Social Impact Study of Smart Manufacturing and Industry 4.0. Dr. Srivastava has received several notable international accolades, including the Sakura Research Fellowship and the Swiss Government Excellence Scholarship.

Authors:

Rory O'brien Creganna Medical
Vicente Moritz PRISM Research Institute, TUS Athlone
Paul Mcdonald PRISM Research Institute, TUS Athlone
Declan Devine PRISM Research Institute, TUS Athlone
Rupal Srivastava Confirm Smart Manufacturing, TUS Athlone