2 Material Development for Microfluidic Systems
The choice of materials for microfluidic sensor fabrication is a significant factor in
performing chemical and physical operations inside the microchip [ 7 , 8 ]. The
surface chemistry and mechanical stability of substrate materials are two major
considerations for microfluidic device fabrication [ 9 ]. The surface modification and
handling of fluids within the chip are primarily controlled by the surface properties
of the material while the mode of detection is governed by the transducers
employed. Although a variety of transducer methods have been feasible toward
the development of biosensor technology, the most common methods are electro-
chemical and optical followed by piezoelectric. A broad range of materials from
silicon, glass, polymers, and paper have been demonstrated as viable compatible
materials for creating advanced and low-cost microfluidic devices, with embedded
micrometre-sized elements, to provide unique and often combined functionalities
for microfluidic processing (Fig.6.2).
2.1 Inorganic Materials
2.1.1 Silicon
The first generation microfluidic devices were fabricated using glass and silicon-
based materials due to their widespread availability in the semiconductor industry
Fig. 6.1 Idealized POC device [ 5 ] reproduced with permission from John Wiley & Sons, Inc. The
POC device consists of a disposable part, with a loading port for sample introduction, a sample
preparation and metering unit (for pre-concentration, amplification, cell lysis), a microfluidic
processing unit (for splitting, moving, and mixing samples and reagents), a sensor unit (to target
recognition receptors) for labeled or label-free detection, and a signal transduction unit with
electronic readout circuit
6 Materials and Surfaces in Microfluidic Biosensors 147