Hypodermic needle sharpness testing

Customised engineering example

Hypodermic needles are tested to determine how their design influences the ease of insertion into the skin, patient pain and skin trauma. In addition, they are tested to determine their efficacy in piercing elastomer closures on vials.

Sharpness is determined by measuring the penetration force of a needle into a known medium which closely replicates skin (eg. polyurethane rubber).

A membrane of uniform thickness is held under constant tension and can be repositioned to allow many tests to be performed. For a number of clients, Mecmesin has designed and manufactured custom fixtures for holding a variety of hypodermic needle assemblies, and for stretching the rubber medium over an aperture for penetration testing.

A key aspect of the fixturing is to ensure that the needle must not flex during the test and that the angle of presentation is always consistent.