Development of a process for generating three dimensional microbial patterns amenable for engineering use.

We describe in detail a process for generating three-dimensional patterns of microbes on an optimum
substrate in such a way that the patterns are amenable for engineering applications. Further, we
demonstrate approaches that make it possible to use the three-dimensional microbial patterns for
applications outside the realm of the life sciences. Specifically, the microbes are normally grown on a gel
media. In order to separate the grown patterns from the gel, we have introduced a permeable
membrane. These membranes provide support for the growth of microbial colonies and allow them to
be used in other applications. Among the membranes, a polyvinylidene fluoride membrane could be
made suitable after its surface treatment to promote microbe adherence. We demonstrate two
approaches for generating the required patterns. In both cases, a two dimensional pattern of an ink is
dispensed on the membrane kept on the media. The subsequent growth of microbes is used to acquire
the three dimensional pattern. The two proposed approaches are a microbial approach and an
antimicrobial approach. In the former, baker's yeast, which was found to be the most suitable among the
microbes tested, is dispensed in an ink form on selected locations on a PVDF membrane. The same
pattern evolves upon growth. In the antimicrobial approach, the PVDF membrane is fully coated with
yeast ink and iso-amyl alcohol as growth inhibitor is dispensed in a pattern. After growth of the yeast, the
pattern evolved is the negative of the dispensed pattern. The fabricated patterns are proposed to be
used in applications such as stamps for printing micro-electronics, microlenses, microfluidics and for
direct use in braille printing. A polydimethyl siloxane stamp fabricated using a grown yeast pattern for
micro-contact printing is also demonstrated.