Process Development and Fabrication
Micropumps have been fabricated using different techniques in metal (e.g. aluminium), silicon/glass and polymers (e.g. polycarbonate). Figure 4-1(a) shows the breakdown of materials used in micropumps based on a survey of the literature. The type of material used is in general closely related to the fabrication technique employed (Fig. 4-1(b)), each having its advantages and limitations. The metal pump has the advantage of fast prototype fabrication and readily available equipment. The fabrication of a pump in silicon can be a much more complicated and involved process. However, the advantages are that many pumps can be fabricated at the same time (i.e. batch fabrication) and consistent micrometer size features can be produced. The use of silicon and glass has also advantage over metals as pump materials as they are more resilient to aggressive media thus making them more suitable for applications such as chemical analysis systems. The use of polymers as pump material has the advantage that the material is inexpensive compared with more commonly used materials in MEMS devices. Based on one master (i.e. the mould), it is possible to fabricate thousands of pumps. The main disadvantage of using polymers at this point of time is the lack of maturity of the fabrication technique (usually by means of the LIGA process (a German acronym for Lithographie, Galvanoformung, Abformung meaning lithography, electroplating, and moulding respectively)) and the unavailability of the equipment needed to support this process. For details of these processes, the reader can refer to .
KeywordsSilicon Nitride Etch Rate Nitride Layer Laser Drilling Glass Wafer
Unable to display preview. Download preview PDF.