This paper presents a miniature,shock-wave driven,needle-less syringe to deliver liquid drugs into soft targets in human body,in a controlled manner,with minimal pain,breach and bleeding.The syringe can deliver liquid or colloidal drugs into human skin,to the depth of dermis,without disrupting much of its microcirculation system.The device can also be used to deliver liquid drugs into soft tissue in human body.The syringe operates by virtue of the impulse of an incident shock wave,which instantly displaces a soft,rubber diaphragm into the drug cavity,ejecting a sufficient volume of drug from the cavity through a micro-nozzle as a high-speed microjet.The characteristics of the delivery were obtained by analyzing the strength of the impulse of the shock wave and measuring the velocity of the generated liquid mierojet.The microjet had a constant velocity over 6 mm distance from the nozzle,ranging from 60 to 80 rn/s depending on the fill gas pressure.The penetrating ability of the jet was investigated by delivering it into human skin samples,gelatin slabs and other soft targets.The deliveries were analyzed theoretically and the predicted results were compared with the experimental observations.This new liquid vaccine/drug delivery technique can reduce pain,trauma,and contamination,and can offer an important cost-effective solution to needle-free health care worldwide.