Rapid Prototyping of a Conceptual Syringe Design

Abstract

The thesis focuses on a modular syringe design idea that shows how the barrel of the syringe can be replaced without completely disregarding the entire syringe. The syringe design consists of barrel sealed on both ends and prefilled with medicine which can be connected to the plunger during operation. Focusing only on the concept rather than clinical use, this study also investigates whether additive manufacturing can support a prototype of a modular medical device. The idea was inspired by the prefilled insulin pen injectors but does not attempt to compete or replace the prevailing insulin pens. While the pen injectors are manufactured by injection molding, this thesis focuses on exploring the potential of additive manufacturing in producing prototypes for early device development. The aim is to create a simple, reusable, and cost-efficient design that demonstrates how modularity can reduce material waste commonly generated by single use syringe systems. Using SolidWorks CAD software, four primary components were modeled and assembled to form a complete modular syringe prototype, emphasizing ease of manufacture, material efficiency, and practical assembly. The parts were modified multiple times leading to the development of two parts for 3D printing. SolidWorks simulation study was run based on maximum possible barrel wall pressure of 92 kPa. Upon simulation, the results showed the wall stress induced by the pressure as 0,38 MPa, which is 1,15 % of the material’s yield strength. Optimization study was conducted on SolidWorks to show how the software can help in design changes and reduce material waste. After optimizing using SolidWorks, it was possible to reduce mass of 2,96 g which is 30,67% of initial material mass. Weighted decision matrix further highlighted the benefits of additive manufacturing of modular devices. Along with advantages, numerous challenges related to additive manufacturing were shown in the thesis indicating the need for improvements in the field. It was identified that additive manufacturing can help in reducing waste in the early prototype development however, clinical use for syringes is not yet feasible and sustainable.