New Concept of Electromagnetic Impact-driven Jet Injector with Enhancement of Jet Power and Control

This study presents an improved needle-free jet injector driven by an electromagnetic actuator based on the impact-driven method (IDM). The developed IDM-v2 system enhances controllability, compactness, and jet performance compared with the previous gas-powered IDM-v1. Experiments using nozzle diameters of 0.2, 0.3 and 0.4 mm and liquid volumes of 0.01, 0.02 and 0.03 mL were conducted to evaluate key jet characteristics, supported by high-speed video camera for transient visualization. The IDM-v2 generated the exit jet velocities of 420 to 508 m/s, corresponding to impact peak pressures of 7.5 to 70 MPa and jet powers of 1.88 to 5.67 kW. The system also exhibited a shorter multi-pulse interval and higher transient peak pressure than IDM-v1, indicating improved energy transfer and dynamic response. The consistency between visualization and pressure measurements confirms the reliability of the electromagnetic actuation. The high jet power and small injection volume suggest strong potential for efficient transdermal delivery, although further biological evaluation is required to assess clinical performance.