Analytical Model Of Spherical Projectile Penetration Into Ballistic Gels

Biolistic drug delivery is a novel method for the intradermal needle-free injection of a wide array of drugs and vaccines. These devices project microparticles, containing a drug or vaccine, onto the skin at speed up to 500 m/s. To achieve the optimal therapeutic or prophylactic effect, the particles need to be delivered to specific skin layers. In order to evaluate the critical parameters and understand their influence on the penetration depth, an analytical model has been developed. The model is based on the real time tracking of the position of a ball shot into ballistic gelatin and Perma-Gel using a high-speed camera. This macro-scale model is then analyzed in a micro-scale perspective and compared to the results observed with the biolistic needle-free injector. Finally, based on the model, a method to characterize the viscosity and the ultimate strength of gels at intermediate strain rate impact is proposed.