In-vitro studies of jet injections

In this study, needle-free jet injection dynamics were studied using homogeneous gelatin as model substrates. Whilst keeping nozzle properties such as orifice diameter (d_o) and ampoule volume (V) constant, we demonstrate the effect of standoff (s), confinement around the gel, storage modulus (G^′) of model gel and liquid viscosity (μ) on the penetration depth of the jet injection. High-speed imaging was used to observe the liquid jet propagation and dispersion dynamics, whilst a load cell was implemented to measure the impact force for different standoff distance and viscosity of the liquid. The different parameters considered showed significant effects on penetration depth, with non-linear dependence on standoff being the key result, which may have implications for future injector designs. Moreover, the effect of confinement serves as a caution of using gelatin substrates as a proxy for human tissue.