Design and Analysis: Servo-Tube-Powered Liquid Jet Injector for Drug Delivery Applications

Abstract

The current state of commercially available needle-free liquid jet injectors for drug delivery offers no way of controlling the output pressure of the device in real time, as the driving mechanism for these injectors provides a fixed delivery pressure profile. In order to improve the delivery efficiency as well as the precision of the targeted tissue depth, it is necessary to develop a power source that can accurately control the plunger velocity. The duration of a liquid jet injection can vary from 10 to 100 ms, and it generate acceleration greater than 2 g (where g is the gravity); thus, a platform for real-time control must exhibit a response time greater than 1 kHz and good accuracy. Improving the pioneering work by Taberner and others whereby a Lorentz force actuator based upon a voice coil is designed, this study presents a prototype injector system with greater controllability based on the use of a fully closed-loop control system and a classical three-phase linear motor consisting of three fixed coils and multiple permanent magnets. Apart from being capable of generating jets with a required stagnation pressure of 15–16 MPa for skin penetration and liquid injection, as well as reproducing typical injection dynamics using commercially available injectors, the novelty of this proposed platform is that it is proven to be capable of shaping the real-time jet injection pressure profile, including pulsed injection, so that it can later be tailored for more efficient drug delivery.

Dynamic interaction of injected liquid jet with skin layer interfaces revealed by microsecond imaging of optically cleared ex vivo skin tissue model

“…Based upon the actuation type used for the displacement of the piston, they are usually classified as mechanically driven or electrically driven injectors [ 4 ]. A compressed spring [ 5 – 13 ] or an expanding gas or air [ 14 – 21 ] is used as the energy sources for mechanical actuators, whereas electrical actuators use the Lorentz force [ 22 – 29 ] or piezoelectric energy [ 30 , 31 ] to pressurize the injection fluid to obtain high-velocity microjets. These propelled microjets have velocities of approximately 100 m/s, which may be sufficient to penetrate the skin surface (reported to be around 15 MPa [ 32 ]) and deliver the drug to a particular depth in the skin tissue.…”