The trend in microfluidics is no longer to drive for smaller fluid channels (these can be micro-milled to 0.2mm width/depth or less), but to integrate more functions, such as electronic or optical analysis, into a device. Design and structuring of specific surface features at the nano-level (below 1 micro meter in size) can modify the wettability of a surface to help control the movement of fluid. The same structuring processes can be used to provide diffractive optics, for example, to shape the beam of light emitted from a light emitting diode (LED) needed for analysis work.
Surgical instruments & devices
Small slots or radii in metal parts or mould inserts can be cut to <0.050mm width, and plastic parts can be micro injection moulded in mould tools using steel ejector pins <0.20mm diameter for part ejection. Holes <0.1mm diameter can be moulded, and when holes too small for moulding are required, hole sizes <0.030mm diameter can be produced by laser machining. In micro-moulding, the gate size (for polymer injection) can be as small as 0.060mm diameter.
These capabilities enable the manufacture of micro devices for catheter tips, micro-needles, and small surgical instruments. Another application is in dental surgery, where a new device has been developed for root canal treatment, using a micro-moulded x-ray opaque material with a hygroscopic coating. The component moulded for this application is a 43mm long 'probe' tapering to a 0.18mm tip diameter.
Implanted devices
Some treatments require bio-resorbable devices to be used, or structural components to be permanently implanted. The scale of parts that are possible with micro-moulding, ie. parts <1mm in size with features much smaller than this, opens up new possibilities. At this scale, the problem becomes more one of handling than of manufacturing. However, micro-moulding also opens up opportunities for slightly larger scale parts that include micro/nano surface features or holes as part of their structure.
Micro Systems (UK) Ltd will be exhibiting at:
MMLive, Ricoh Arena, Coventry, UK, Oct 20-21, 2009. (Stand D7). Compamed (alongside Medica), Dusseldorf, Germany, Nov 18-20, 2009. (Stand G19.4)
