Abstract: Provided is a micro-jet drug injection device comprising: a pressure chamber having a pressure driving liquid hermetically filled therein; a drug chamber having a micro nozzle defined in a wall; an elastic membrane elastically expandable and restorable and to separate the pressure chamber from the drug chamber; an energy-focusing unit concentrating energy on the pressure driving liquid in the pressure chamber; and the storage unit supplying the drug solution therein into the drug chamber through a drug supply channel. The drug chamber has a partial inner space defined therein. The partial inner space is in fluid communication with the drug supply channel and is partially defined by the membrane. A nozzle closure is disposed inside or outside the drug chamber. The nozzle closure blocks inflow of air outside the micro-nozzle into the partial inner space after the elastic membrane has expanded and before elastic recovery of the membrane is completed.

Abstract: In a needleless syringe according to the present invention, a current is supplied to a solenoid coil to generate a magnetic field so as to move a moving magnetic body and a piston forward, and when the current to the solenoid coil is cut off, an elastic member for the moving magnetic body moves the moving magnetic body backward and an elastic member for the piston moves the piston backward, so that the piston to be injected by pressurizing a drug is configured to reciprocate repeatedly forward and backward and thus, a predetermined drug can be repeatedly injected at high speed. In addition, according to the present invention, time for which the current is applied to the solenoid coil, is adjusted to minimize recoil without adding a recoil offset structure so that the structure is simple and convenience of use can be improved.

Abstract: Provided is a micro-jet drug injection device comprising: a pressure chamber having a pressure driving liquid hermetically filled therein; a drug chamber having a micro nozzle defined in a wall; an elastic membrane elastically expandable and restorable and to separate the pressure chamber from the drug chamber; an energy-focusing unit concentrating energy on the pressure driving liquid in the pressure chamber; and the storage unit supplying the drug solution therein into the drug chamber through a drug supply channel. The drug chamber has a partial inner space defined therein. The partial inner space is in fluid communication with the drug supply channel and is partially defined by the membrane. A nozzle closure is disposed inside or outside the drug chamber. The nozzle closure blocks inflow of air outside the micro-nozzle into the partial inner space after the elastic membrane has expanded and before elastic recovery of the membrane is completed.