Prototyping of microfluidic systems with integrated ... - DTU Nanotech

Chapter 3
Polymer materials
– mainly Topas
3.1 Introduction
When the concept of micro total analysis systems or µTAS was introduced
by Manz et al. in 1990 [1], the predominanant materials used
as substrates in the manufacturing of these systems were silicon and
glass. The reason for this was the existence of well-developed methods
for processing these materials, used in microelectronics. Here, methods
like photolithography and wet etching of silicon and glass had been used
and optimised for several decades. Several disadvantages when using
these materials and methods for microfluidic systems became, however,
increasingly evident. This happened with the ongoing commercialisation
of the technology, following the large number of developments and
discoveries triggered by the introduction of the concept [17]. The search
for alternative substrate materials for lab-on-a-chip systems lead to an
increased focus on polymers because of several factors.
3.1.1 Why polymers?
Firstly, the cost of the silicon and glass is up to two orders of magnitude
larger than the cost of substrates in polymers such as poly(methyl
methacrylate)(PMMA) or polycarbonate (PC).
Secondly, the many steps used in silicon processing, such as cleaning,
wet and dry etching, resist coating, and lithographic structuring, are
applied serially to each structure, thus increasing the fabrication time and
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