Experimental study on shock tube flows for the application of needle-free drug delivery

Recently, an innovative drug delivery system has been developed to deliver drug particles to the human shin without using any external needles. In order to obtain enough momentum, drug particles are accelerated by means of high speed gas produced in a Contoured Shock Tube (CST), so that particles can penetrate through the outer layer of the skin. The CST system consists of a classical shock tube with two diaphragms and an expanded supersonic nozzle. Schlieren visualization technique was used to observe shock waves in a CST of needle-free drug delivery system. The visualization of density gradient between the front and the behind of the shock wave is obtained from 2D density stratified flow in the shock tube. The structure and propagation of Shock waves were obviously observed in present schlieren images. In the pressure measurement, six high sensitive pressure transducers are used to record the pressure change as the shock wave moves through the test section, from which data on shock wave propagation was obtained.