Biomedical Engineering Reference
In-Depth Information
deep lithography, electrodeposition, and molding process steps.
LIGA offers high potential regarding miniaturization, freedom of
design, and mass production. Micro-gear system produced from a
nickel iron alloy by means of LIGA has been shown in Fig. 1.
7
.
Figure 1.7
Micro-gear system produced from a nickel iron alloy by means
of LIGA technology (Source: Micromotion, IMM) [108]. Reproduced by kind
permission from the publisher.
However, the ultraprecise microstructures with extreme aspect
ratio could only be generated by deep X-ray lithography. Difficulties,
for example, in the access to synchrotron radiation facilities have
limited the commercialization of LIGA technique in mass fabrication.
1.7 MICRO- AND NANO-MACHINING BY ULTRASHORT
VOLTAGE PULSING TECHNIQUE
Use of electrochemistry in micro-machining has been a matured area
[111]. In contrast to the conventional processes of electrochemical
micromachining, where the gap between the electrodes is usually
0.1 mm and direct current is applied, a novel electrochemical
microfabrication method using a gap in “μm” range and very short
voltage pulses of some tens of nanoseconds was developed. The
short pulse confines electrochemical processes correspondingly,
removal of material to a very narrow volume to enable a precise
nanomachining. Ultrashort pulses can be employed to machine
conducting materials with lithographic precision [112]. Resolution
can be improved significantly through the use of ultrashort voltage
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