Vascular access for haemodialysis is often associated with pain and a high incidence of complications due to the large needles used. This research aimed to develop a novel cannulation device featuring a smaller initial insertion profile than current state-of-the-art needles, with the ability to expand to a functional lumen comparable to conventional designs, while remaining suitable for routine clinical use.

Based on the background information, design requirements and evaluation criteria for the needle were established. A morphological chart was then created from these requirements, from which eight concepts were generated, representing four distinct dilation principles. These concepts were systematically evaluated against the predefined criteria. Following this evaluation and a proof of principle, the metal sheet cannula with a slide-in dilator emerged as the most promising design and was selected for prototyping and testing. The concept was assessed in terms of operating force, insertion force, and tissue damage. Additionally, the most suitable operating movement for manual activation was evaluated. These steps resulted in the development of the final design and prototype.

Results demonstrated that the dynamic needle can achieve competitive insertion forces and tissue damage once further optimized. The primary limitation identified was the relatively high operating force, mainly due to internal friction between the cannula and dilator. Material and surface optimisations, as well as mechanical assistance strategies, were proposed to address this limitation.

This study presents a functional concept for a dynamic-diameter haemodialysis needle that has the potential to reduce patient discomfort and complications. Future work should focus on optimising the operating force and needle surface properties, evaluating preclinical and clinical performance, and developing scalable manufacturing processes to enable routine clinical use.