Micro-fluidics

S. Valkai, H. I. Kirei, L. Oroszi and P. Ormos
Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, H-6726 Szeged, Hungary

Abstract

A fully integrated microfluidic sorter is introduced. It is able to count, characterize and sort micrometer sized articles and cells. All functions of the device are performed by light. The objects to be sorted are counted optically, they are characterized by measuring their fluorescence. Even the sorting itself, directing the particles into different channels is performed by the pressure of light. The device is built by photopolymerization, from a light cured optically clear resin upon a glass plate support. The whole structure is created in a single photolithography step. The microfluidic channels and optical waveguides that carry the illuminating, detecting and sorting light form a single integrated structure. The supporting units, like sample reservoirs, pumps, light sources, light detectors are easily connected to the device from the outside. The device is optimized for simplicity. It is a proof-of-concept instrument, it demonstrates that it is possible to build simple optically driven microfluidic systems that perform complicated functions.

C.A. Griffiths (1), S. S. Dimov (1), E.B. Brousseau (1), C. Chouquet (2), J. Gavillet (2), S. Bigot (1)

(1) Manufacturing Engineering Centre, Cardiff University, Cardiff CF24 3AA, UK
(2) French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054 Grenoble, France

Abstract

Micro injection moulding as a replication method is one of the key technologies for micro manufacture. The understanding of process constraints for a selected production route is essential at both the design stage and during mass production. In this research a tool surface treatment is used to study the effects of demoulding a part with micro features. In particular a tool coated with diamond like carbon (DLC) will be compared to an identical tool without coating. Through a range of experimental trials the effects of four process parameters, namely melt and mould temperature, and cooling and ejection time will be used to evaluate the demoulding process. Using two polymer materials PP and ABS, a special attention is paid to the forces present in demoulding and conclusions are made about the influence of DLC surface treatments and the factors affecting demoulding.

M. Heckele (a), M. Worgull (a), T. Mappes (b), G. Tosello (c), T. Metz (d), J. Gavillet (e), P. Koltay (d), H. N. Hansen (c)

(a) Forschungszentrum Karlsruhe (FZK), Institute for Microstructure Technology (IMT), D-76344 Eggenstein-Leopoldshafen, Germany
(b) University of Karlsruhe (TH), Institute for Microstructure Technology (IMT), D-76344 Eggenstein-Leopoldshafen, Germany
(c) Technical University of Denmark (DTU), Department of Mechanical Engineering, DK-2800 Kgs. Lyngby, Denmark
(d) Laboratory for MEMS Applications, Department of Microsystems Engineering (IMTEK), University of Freiburg, George-Koehler-Allee 103,79110 Freiburg, Germany
(e) French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054 Grenoble, France

Abstract

Sub-micro structured surfaces allow modifying the behaviour of polymer films or components. Especially in micro fluidics a lotus-like characteristic is requested for many applications. Structure details with a high aspect ratio are necessary to decouple the bottom and the top of the functional layer. Unlike to stochastic methods patterning with a LIGA-mould insert it is possible to structure surfaces very uniformly or even with controlled variations (e.g. with gradients). In this paper the process chain to realize polymer sub-micro structures with minimum lateral feature size of 400 nm and up to 4 μm height is presented.

Chantal Khan Malek and Laurent Robert
Institute FEMTO-ST/Dpt. MN2S, CNRS UMR 6174, 32 Av. de l’Observatoire, 25044 Besançon, FRANCE

Abstract

Polymer-based microfabrication technologies are gaining momentum as they enable low cost fabrication of a variety of
microsystems, with major developments in optical and microfluidic systems. The use of dry film resist for microsystem
applications is briefly reviewed. A method based on the lamination of commercial SU8 dry films and photolithography for the formation of flexible thin film micro-devices is presented. Fast prototyping of multi-layer microfluidic simple chips with embedded channels is reported.

D. Clausi, J. Peirs, D. Reynaerts
Katholieke Universiteit Leuven, Department of Mechanical Engineering, Division PMA

Abstract

Shape Memory Alloys have a considerable potential for integration into microsystems, where scaling down of their size allows favorable exploitation of the intrinsic adaptive capabilities, providing an actuation mechanism for applications (e.g. micropneumatics) requiring large force control and large actuator stroke. However, the implementation of these materials into actual structures is rather complex and mostly confined to depositing thin NiTi films onto certain target substrates, resulting in devices having a relatively high cost-per-piece. This paper is aimed at investigating a novel approach for batch integration of SMA to microactuators, which might provide a cost-effective alternative to thin film technology while enhancing functional properties and design flexibility. Indicative requirements for the actuator design have been drawn from typical microvalve applications. In order to evaluate the actuator performance, brass microcantilevers have been produced, with prestrained SMA thin wires bonded on top of them, eccentrically with respect to the cantilever’s neutral plane. The activation of SMA element is obtained by direct heating through electrical current. The bending actuation of the cantilever leads to large strokes, expected to match the requirements of a wide range of applications.