4M Knowledge base - papers
Severin Dahms, Frederik Bundgaard and Oliver Geschke
MIC - Department of Micro and Nanotechnology, Technical University of Denmark (DTU), Building 345 East, 2800 Kgs. Lyngby, Denmark
Waveguides are an excellent means of integrating sensor components in single use microfluidic polymer systems. However, most processes for producing on-chip waveguides require several process steps, some of which are not suited for mass production. We report a simple procedure in which two different grades of the cyclic olefin copolymer (COC) Topas® are used as substrate and core layer. In a spin coating process a Topas® grade with high refractive index is spin coated onto the injection moulded substrate with lower refractive index, thereby generating a core layer. A simple hot embossing process enables simultaneous structuring of waveguides and microfluidic channels in the core layer. In a final step the microfluidic structures can be closed with a lid, either by thermal bonding or by laser transmission welding.
The refractive index and glass transition temperature Tg can be altered by changing the ratio between the two copolymers of Topas®. The low optical transmission loss of the material, along with its chemical resistance and low water absorption, makes Topas® a good choice for making integrated optics in microfluidic systems.
T.Rogers & I.Malmros
Applied Microengineering Limited, Unit 8 Library Avenue, Didcot, Oxon.,OX11 0SG, UK
A new multi-purpose MEMS fabrication tool is described. The tool enables in-situ aligned embossing and nanoimprinting, in addition to surface activation and aligned wafer bonding. De-embossing is also included in-situ via the use of vacuum chucks and chamber pressurisation. The multi-purpose tool enables the fabrication of bonded, embossed, multi-layer, micro-fluidic devices, for example PDMS structures on silicon, including the alignment of the embossed structure to any pre-existing patterning on the silicon. Examples are presented of various structures that have been made using the tool along with a description of the principles of operation.
D. Andrijasevic(a), W. Smetana(a), S. Zoppel(b), W. Brenner(a)
a: Institute of Sensor and Actuator Systems, Vienna University of Technology, 1040 Vienna, Austria
b: Forschungszentrum Mikrotechnik, Fachhochschule Vorarlberg, 6850 Dornbirn, Austria
The latest results achieved during the investigation of possibilities for producing MEMS in unfired green Low Temperature Cofired Ceramic (LTCC) by embossing technique are presented in this paper. Ceramic tapes in unfired state are subjected to compression by means of using tools specially designed and developed for this purpose. Structures obtained in this way demonstrate high repeatability and surface quality comparable with those gained by other techniques. In comparison with traditionally used laser cutting or injection moulding for ceramic processing, this technique offers better resolution and further miniaturisation, improved rigidity of small structures and possibility to profile the vertical walls in U- and V-shapes. The main focus of this paper will be on the optimisation of embossing parameters (embossing force, embossing time and temperature) in order to get repeatable and reliable results. Structures produced in this way could be successfully used in optical as well as in medical applications.
M. Sahli(a)(b)(c), C. Millot(a), C. Roques-Carmes(a), C. Khan Malek(b), J.C. Gelin(c) and T. Barriere(c)
a: Surface Microanalysis Laboratory (LMS), ENSMM, 25030 Besançon cedex, France
b: FEMTO-ST Institute/Dpt. LPMO, CNRS UMR 6174, , 25044 Besançon cedex, France
c: FEMTO-ST Institute, CNRS UMR 6174, ENSMM, 25030 Besançon cedex, France
This paper focuses on the comparison between two manufacturing techniques to realize micro-structural replications on a polymer substrate. The micro-technologies that are considered consist in replication through micro-injection moulding on one hand, and in replication through hot embossing in the other hand. The same mould with microstructured cavities produced by high-speed milling or indentation was used for both replication methods. The replication process parameters are analyzed in both cases, and the resulting polymeric shapes and surface states are characterized in using 3D scanning mechanical microscopy. It is shown that both replication processes give accurate results if the processing cycle as well as pressure and temperature are well adapted.
Chantal Khan Maleka, Gaël Thuilliera, Roland Duffaitb , Laurent Guyoutc
a Laboratoire FEMTO-ST, CNRS UMR 6174, Département LPMO, 32 Avenue de l’Observatoire, 25044 Besançon Cedex, France.
b Centre de Transfert des Micro et Nanotechnologies (CTMN), 39 Avenue de l’Observatoire, BP 1445-25007 Besançon Cedex 3, France.
c Department of Applied Mechanical Engineering, University of Franche Comté, 16 Route de Gray, 25030 Besançon Cedex, France.
Our approach uses a two-step replication process for hot embossing and a rigid polymeric intermediate mould. This process overcomes some geometrical limitations in microstructured mould fabrication, enables positive-tone imprinting, prolongs the lifetime of the master, and lowers the overall cost of the replication process.
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