Optimal voice coil actuators for needle-free jet injection

We present a scaling model for electrically-actuated needle free jet injectors, establishing the relationship between injection volume and motor size. Using an analytical electromagnetic model for the motor, we derive an optimal motor design, and show that this design is approximately scale-invariant. To illustrate the utility of this model, we then describe the design of a motor for use with 300μL disposable injection ampoules with a mass of just 300g, including a light-weight support structure. Experimental verification of the motor performance shows close agreement to model predictions, with a peak force of 1000 N/kg and a 150 m/s water jet delivered.