Quantifying User-Applied Forces on Prefilled Syringe Luer Cone: A Human Factors Ergonomics Study

This study investigates the real-world forces and torques applied by professional healthcare users to the luer cone region of prefilled syringes (PFSs) during typical handling and preparation tasks. While standards such as ISO 11040-4 address mechanical robustness, limited data exist on the magnitude and nature of forces various users actually apply during device useÂinformation that is critical for ensuring patient safety and product reliability. To address this gap, a custom measurement platform replicating a 1.5 mL Luer Lock PFS, instrumented with multi-axis force and torque sensors was developed. Participants (n=60 nurses and retail pharmacists) performed key handling tasks, including unscrewing the tip cap, screwing on a needle, removing the needle cap, and activating the safety needle shield-while applied forces were recorded. Four safety needle types-two hinge-based, one slider-based, and one spring-based retractable mechanism-were included in the evaluation; all safety needles require users to actively deploy the safety guards. Tasks were completed under three instruction conditions: naturalistic use ("actual"), elevated force use ("confident"), and perceived upper-bound force ("maximum acceptable"). The results quantify the range and characteristics of user-applied forces across tasks, needle types, and instructional prompts, providing valuable data to inform technical specifications for luer cone interfaces. In addition, these findings highlight the importance of study design choices such as task selection and instructional prompting when conducting human factors force characterization studies intended to support robust, use-relevant specifications setting. These insights aim to support the development of PFS devices that are both robust and user-friendly, ultimately ensuring the devices designed are suitable for the capabilities of their intended users.