Micro Assembly Injection Moulding Potential Application in Medical Science

Prof. Dr.-Ing. Dr.-Ing. E.h. Walter Michaeli, Dipl.-Ing. Dirk Opfermann
Institute of Plastics Processing (IKV) at RWTH Aachen University, 52062 Aachen, Germany

Abstract

The miniaturisation of technical products becomes more important in many technological areas. Many functions can be optimised by the use of micro systems. On less space more functions can be integrated. In the field of medical technology miniaturisation means also new methods of treatment with fewer side effects on the patient. New cures are being developed as a result of the miniaturisation of medical instruments, such as the key hole surgery. Polymers are spread widely in the field of medical applications. Since plastics are a relatively cheap material and polymer parts can easily be reproduced in high series and accuracy, for examples by injection moulding, their use as disposable articles is predetermined. Polymer materials offer a wide range of properties that can be chosen according to the functional necessities.

Injection moulding can be used also as an assembly technology. The so called micro assembly injection moulding technology includes the generation of hybrid micro systems by overmoulding inlay parts. For detailed examinations a specific demonstration part has been chosen to display the potential of this technology in medical science. The chosen part consists of a carbon-fibre reinforced PEEK puncture needle, which incorporates three lumens. The selected materials allow for an use of the needle during magnetic resonance imaging. In order to attach additional equipment a plastics connector is overmoulded to the needle. The investigations focus on the process by characterising the influences of temperature, injection moulding parameters and material combinations on the resulting bond strength between needle and connector. The bond strength is crucial for the proper function of the complete system. Present investigations at the Institute of Plastics Processing (IKV) focus a special testing method to evaluate the bond strength. Initial results show bond strength comparable to existing systems using metal needles. Therefore micro assembly injection moulding offers a promising alternative to conventional assembly technologies.