ENGINEERING INSIGHT
Asingle-column universal material tester played a versatile role in the development of a needle-free injection system. Designed by PowderMed Ltd. (Oxford, UK), the single-use injection system uses proprietary particle-mediated epidermal delivery (PMED) technology. PMED delivers therapeutic DNA vaccines into the skin without needles in a dry powder formulation of microscopic particles. The LRX tester from Lloyd Instruments (Fareham, Hants, UK) was used by PowderMed to perform a number of crucial tests on the drug-delivery device.
The powdered vaccine is contained in a cassette sealed with a thin-film membrane. The delivery system includes a self-contained microcylinder filled with pressurized helium. When the user presses down on a button, the tip of the cylinder breaks off and the gas is released. This ruptures the cassette membrane and forces the particles into the skin’s epidermal layer. Several critical components of the system were evaluated using a single tester fitted with various jigs to hold the different parts.
For instance, testing methods were developed to evaluate the load required to actuate the device. The amount of necessary force had to be sufficient to prevent accidental actuation; conversely, the mechanism could not be so stiff as to make it difficult to press down on the button and operate the device. To ensure that the pressurized gas performs repeatably with each delivery device, engineers used the tester to evaluate the force required to penetrate the film. The instrument was also used to measure the load required to break the microcylinder’s tip, and the load required to assemble and disassemble the cassette.
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