Particle cassettes

A method of producing a particle cassette for a needleless syringe device, said method comprising the steps of:

• (a) providing a first cassette part having a first rupturable membrane bonded thereto;
• (b) providing a second cassette part having a second rupturable membrane bonded thereto;
• (c) aligning said first and second parts longitudinally;
• (d) applying a predetermined force in the longitudinal direction so as to push the first and second cassette parts together to cause plastic deformation of a part of said cassette so as to create a hermetically sealed chamber between said first rupturable membrane and said second rupturable membrane,
• wherein said predetermined force applied in step (d) is chosen according to either of the following formulas:
• F∃0.1CAmax or F∃2C
• wherein F is the predetermined force in Newtons, C is the compressive yield strength of the portion that plastically deforms in MPa and Amax is the maximum possible sealing area achievable with the cassette parts in mm2.