234
G. Feng et al.
Fig. 7.23 a, b Optical micrographs of the Y-branched channels before and after drawing, respectively [41]. Microscope image of c conical spiral inscribed in the glass and d the etched microchannel
[42]. e Optical micrograph of a helical channel fabricated by segmented chemical etching method
[43]. f, g micrograph of a 1.6-cm-long microchannel embedded in porous glass before postannealing
and postannealed, respectively [44].
length of 1.140 cm and aspect ratio of 522. There are some extra corrosion inlets
on the microfluidic channel prepared by this method. (4) Fabrication of microfluidic
channels using porous glass as substrate [44]. Formation of hollow microchannels
in a porous glass substrate immersed in water by FLDW method and postannealing
of the glass substrate at ∼1150 °C by which the porous glass can be consolidated. A
square-wavelike channel with a total length of ∼1:4 cm and a diameter of ∼64 μm can
be easily produced ∼250 μm beneath the glass surface. Porous glass is unavailable
at the market.
More recently, Feng et al. have developed a new technique which firstly fabricates
channel on the surface of the substrate using FLDW followed by chemical etching
and then covers a thin layer of PDMS film on substrate to form three-dimensional
semi-occlusive microchannels. The conical feature brought by etching selectivity can
be effectively reduced, because the channels are fabricated on the surface of substrate;
thus, there is no problem of suffering different etching period. Via this technique,
various homogeneous networked semi-occlusive microfluidic can be fabricated on
the surface of silica.
7.4.2 Fabricating Micro-grid
Micro/nano-surface structures were fabricated using optical diffraction [45, 46]. The
obtained diffraction pattern was imprinted on the surface of the ZnSe wafer. In the
high-intensity regions, the ZnSe wafer was ablated and generated a surface depression
(valley). In the low-intensity regions, a corresponding protrusion (peak) appeared.
G. Feng et al.
Fig. 7.23 a, b Optical micrographs of the Y-branched channels before and after drawing, respectively [41]. Microscope image of c conical spiral inscribed in the glass and d the etched microchannel
[42]. e Optical micrograph of a helical channel fabricated by segmented chemical etching method
[43]. f, g micrograph of a 1.6-cm-long microchannel embedded in porous glass before postannealing
and postannealed, respectively [44].
length of 1.140 cm and aspect ratio of 522. There are some extra corrosion inlets
on the microfluidic channel prepared by this method. (4) Fabrication of microfluidic
channels using porous glass as substrate [44]. Formation of hollow microchannels
in a porous glass substrate immersed in water by FLDW method and postannealing
of the glass substrate at ∼1150 °C by which the porous glass can be consolidated. A
square-wavelike channel with a total length of ∼1:4 cm and a diameter of ∼64 μm can
be easily produced ∼250 μm beneath the glass surface. Porous glass is unavailable
at the market.
More recently, Feng et al. have developed a new technique which firstly fabricates
channel on the surface of the substrate using FLDW followed by chemical etching
and then covers a thin layer of PDMS film on substrate to form three-dimensional
semi-occlusive microchannels. The conical feature brought by etching selectivity can
be effectively reduced, because the channels are fabricated on the surface of substrate;
thus, there is no problem of suffering different etching period. Via this technique,
various homogeneous networked semi-occlusive microfluidic can be fabricated on
the surface of silica.
7.4.2 Fabricating Micro-grid
Micro/nano-surface structures were fabricated using optical diffraction [45, 46]. The
obtained diffraction pattern was imprinted on the surface of the ZnSe wafer. In the
high-intensity regions, the ZnSe wafer was ablated and generated a surface depression
(valley). In the low-intensity regions, a corresponding protrusion (peak) appeared.