Importance

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Abstract

The invention provides a device which seeks to ensure that substantially all the particles delivered avoid interaction with the so-called 'starting process'. There is provided a needleless injection device comprising a driver chamber (51) arranged, in use, to contain a charge of pressurised gas, a duct section (52) connected to the driver chamber (51) to receive gas therefrom and a closure means (53) for preventing the flow of gas from the driver chamber (51) to the duct section (52) until the closure means (53) is opened. Further, a dose of particles (58) is positioned within the device in the region of the closure means (53). The device is so constructed and arranged that upon opening of the closure means (53), a primary shock wave is produced to travel along the duct (52) in a downstream direction so that a substantially quasi-steady gas flow is established in the duct (52) upstream of the primary shock wave, with the dose of particles (58) being substantially wholly entrained in the substantially quasi-steady flow to be accelerated thereby and expelled from the device.

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First Claim