patent summary for: "improved syringe". a syringe propellant propellant boiling at a predetermined temperature； the syringe comprising a cylinder having a front end outlet, and an axially movable plug in the cylinder. the buffer defines and separates a first chamber and a second chamber, the first chamber being axially front of the tampon and being configured to contain a medicament, and the second chamber axially behind the tampon and being configured to receive a propellant to act upon the tampon. to move the cap axially forward on the cylinder to expel the medicine through the outlet by actuating the syringe. the syringe further comprises a rupturing portion and a third chamber for containing the propellant wherein the third chamber is rupturable. the rupture portion is configured to rupture the third chamber by actuating the syringe to fluidly connect the third chamber to the second chamber and release the liquid propellant from the third chamber so that the pressure in the second chamber increases to at or above the predetermined temperature causing the plug to move axially forward and begin to expel drug from the first chamber through the outlet. when propellant is released into the second chamber, the pressure in the second chamber increases over a first period of time to a first pressure, causing the plug to move axially forward to begin expulsion of the drug from the first chamber. through the exit. the syringe is configured such that as the drug is expelled from the first pressure chamber, the pressure in the second chamber changes over a second period of time from the first pressure to a second pressure. when substantially all of the drug has been expelled from the first chamber, the pressure in the second chamber increases over a third period of time to a third pressure. The magnitude of the second pressure and the rate of pressure increase in the second chamber during the third time period are controlled by the thermal conductivity of the syringe compon
