Medical

A. Schneider (a), L. Frasson (b), T. Parittotokkaporn (c), F. M. Rodriguez Y Baena (b), B. L. Davies (b),
and S. E. Huq (a)

(a) Science and Technology Facilities Council, Rutherford Appleton Laboratory, Technology – Central Microstructure Facility, Harwell Science and Innovation Campus, Didcot, OX11 0QX, UK
(b) Mechatronics in Medicine Lab., Depart. of Mechanical Engineering., Imperial College, London, SW7 2AZ, UK
(c) Institute of Biomedical Engineering, B 422 Bessemer Building, Imperial College, London SW7 2AZ, UK

Abstract

The development of a novel biomimetic neurosurgical probe is inspired by nature. Some insects have spines with a unique surface texture which enables them to penetrate tissue more easily. This surface texture consists of cutting teeth and fin-like pockets on the spine. Instead of drilling, the insect slides its spine into the fibre through the reciprocating motion of independent segments. Applying the same or similar microtexture to a miniaturized neurosurgical endoscope could improve existing tools for brain surgery and brain biopsy. The development of such endoscope could minimize the damage caused by inserting the probe whilst avoiding the risk of buckling, which is a common occurrence when thin flexible probes are axially loaded.
To replicate the surface microtexture, teeth and fin-like high-aspect-ratio microstructures were fabricated. Different geometries of these fins and teeth were studied for insertion into tissue so that the texture could be characterized for friction and tribological interaction with tissue. For these tests, free-standing long and narrow strips with microstructures in up to 525 μm thick SU-8 were designed, fabricated, and mounted onto prototypes made by
stereolithography. This paper focuses on the fabrication of the microtextured strips. The required geometry of these
strips can cause considerable bending. The structures were investigated regarding fabrication and stress conditions.

M.D. Mikrenska (a), P.I. Koulev (a), J.-B. Renard (b)
a Institute of Mechanics, Bulgarian Academy of Sciences, Sofia, 1113, BG
b Laboratoire de Physique et Chimie de l'Environnement, CNRS, 45071 Orléans, FR

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.

S. Wilson(a)(b), A. Welle(c), E.Gottwald(c), A. Molleman(d), P.B.Kirby(b), W.Pfleging(e), J.J.Ramsden(b), M. Heckele(a)
a: Institute for Microstructure Technology, Forschungszentrum Karlsruhe, 76344 Eggenstein-Leo., Germany
b: School of Applied Sciences., Cranfield University, Cranfield, Beds. MK43 0AL, UK
c: Institute for Biological Interfaces, Forschungszentrum Karlsruhe, 76344 Eggenstein-Leo., Germany
d: School of Life Sciences, University of Hertfordshire, Hatfield, Herts.AL10 9AB, UK
e: Institute for Materials Research 1, Forschungszentrum Karlsruhe, 76344 Eggenstein-Leo., Germany
A. Herrero(a), J. Esmoris(a), S. Azcarate(a), S. Geissdoerfer(b), U. Engel(b)
a: Department of Micro & Nano Technologies, Tekniker, Avda. Otaola 20, 20600 Eibar, Spain
b: Universität Erlangen-Nürnberg, Egerlandstrasse 11, 91058 Erlangen, Germany

Abstract

The mass production of micro and meso scale products made of polymers or metals is intimately related to the production of high quality microtooling in stable materials capable to provide an accurate and repetitive performance throughout the whole demanded production. As it is widely known, the WEDM process provides high accuracy but is conceptually limited to the production of ruled features. The SEDM process can be a complement to this aspect but the electrodes must be manufactured by other technologies like WEDM, micromilling, turning, etc. Given the importance of several parameters like dimensional accuracy, tooling material for the different replication processes or tooling production technology, the present paper introduces some tests performed by the 4M Metals Workgroup. The analysis of some components manufactured by members of the group is presented discussing the influence of the EDM process on the machined tooling components and the consequent influence on the replication process.

Patch clamping is a highly sensitive technique used to measure the electrical activity of a cell. It is presently a low throughput cumbersome method which requires highly trained and skilled operators to obtain results of value. Patch Clamping is used in applications which include drug screening where there is demand for high throughput systems (HTS). While there are a few commercially available HTS patch clamping systems on the market using traditional patch clamping materials, there are no systems on the market using novel materials, or for dealing with cell networks – a physiologically important consideration for the developing fields of tissue engineering and understanding cell to cell interactions. This paper presents a summary of traditional patch clamping, mentions some commercially available high throughput patch clamping systems based on traditional materials then, using 4M technologies, introduces some novel materials and potential design approaches and processes for producing a polymer based automated patch clamping system.

Jui-Mei Hsu(a), Sascha Kammer(b), Erik Jung(c), Loren Rieth(d), A. Richard Normann(e), Florian Solzbacher(a)(d)(e)
a: Department of Material Science and Engineering, University of Utah, Salt Lake City, UT, USA
b: Fraunhofer IBMT, St. Ingbert, Germany
c: Fraunhofer IZM, Berlin, Germany
d: Department of Electrical Engineering, University of Utah, Salt Lake City, UT, USA
e: Department of Bioengineering, University of Utah, Salt Lake City, UT, USA

Abstract

Neural interfaces, devices that interact with nervous system, have been developed to help patients with neural disorders to restore lost neural function. The neural interface device requires a conformal and biocompatible encapsulation layer to protect the device during chronic implantation, and to electrically isolate individual electrodes. Parylene-C thin films deposited by a chemical vapour deposition system were studied as an encapsulation layer for neural interface devices. Leakage current tests were used to investigate the encapsulation performance of Parylene-C films, and the results showed hermetic protection as well as long-term (>100 days) stability of the films. The adhesion between Parylene-C and the silicon substrate after several thermal treatments was studied by ASTM tape adhesion tests. Results from these tests suggested that thermal stress may degrade the adhesion force. Parylene samples were subjected to accelerated lifetime testing (85 % relative humidity (RH) and 85 °C) for 20 days, and the film did not show appearance changes as observed by optical microscopy. However, X-ray diffractograms show that the film crystallinity increased during this test.