ABSTRACT
Machining is a process of removing a material from the bulk or surface and leaving the remaining material in the designed shape and dimensions. With the advent of microelectronic manufacturing, various micromachining methods have been pursued for making miniaturized devices (Rai-Choudhury, 1994; Roy et al., 2001; Chang et al., 2008). The various machining techniques presently used can be classied into two categories, namely, physical processing and chemical processing (Pandey and Shan, 1980; Uno et al., 1996), of which wet chemical etching is the widely used method for micromachining (Williams et al., 2003). These well-established processes require chemical or thermoelectric energy to be concentrated at the machining point. Such machining methods may create either a damaged layer or a heat-affected zone on the work surface and could cause potential damage to the metallurgical properties of the workpiece (Uno et al., 1996). Also, the use of hazardous materials (i.e., acids) is unavoidable. The use of biological techniques for material processing has become a promising alternative in the past few years. Recent advances in biotechnology have led to the widespread application of microorganisms in material processing. The innovative use of microbes for microscopic metal removal to achieve microfeatures is considered more environmentally friendly than other means (Zhang and Li, 1996, 1999). The inorganic bacterial pathways responsible for extensive corrosion, which are expensive, can be exploited for benecial purposes (Xia et al., 2010). Biomachining can be dened as “a controlled microbiological process to selectively form microstructures on a metal workpiece by metal removal (or dissolution) using microorganisms” (Uno, 2002). As the size of the bacterium is of the order of microns, it appears to be an ideal tool for micromachining.
