Microfluidics for Biologists Fundamentals and Applications

Si microcantilevers and optical resonators have recently been interfaced with
microfluidics for optical sensing (Fig.6.3). Silicon possesses good thermal conduc-
tivity and is resistant to high temperatures; therefore, it is suitable for applications
requiring a relatively high operating temperature, such as for a polymerase chain

a 14 mm

b

c

e

d

f

Bypass Output

microcantilever

Top Si layer

650 nm

Buried SiO 2

3 μm

PDMS

Fluid microchannel

45 μm

4 μm

10 μm

165 nm

Linear waveguide

Microring Resonator

300 μm

10 mm

OutputsChannel

Input

Fig. 6.3 Microcantilevers (a–e) and a microring resonator (f) made from silicon. (a) Schematic
diagram of waveguides and microcantilever array layout on die. (b) Optical image of two
microcantilevers in a fabricated array. (c) Close up scanning electron micrograph (SEM) image
of the unclamped end of a microcantilever (leftof 165 nm gap) and the differential splitter capture
waveguide (rightof gap). (d) Photograph of complete integrated device showing the fluid
microchannels (red) and control valves (green). (e) Cross-section of fluid microchannel at a
microcantilever array. (f)Top-viewSEM image of a microring resonator and linear waveguide,
visible through an annular opening in the fluoropolymer cladding layer [ 14 ]. Reproduced with
permission from American Chemical Society

6 Materials and Surfaces in Microfluidic Biosensors 149