Biomedical Engineering Reference
In-Depth Information
Fig. 2.
Schematic cross section of a compact mini ET system (see text for detailed description)
transducers, microvalves and micropumps on chips, practically useful micro-
system technology has become a reality [19].
A compact sensor of greatly reduced dimensions (outer diameter
¥
length:
36
46 mm) has been constructed and is shown in Fig. 2. In order to conveni-
ently accommodate enzyme columns and to ensure isolation from ambient
temperature fluctuations, a cylindrical copper heat sink was included. An outer
Delrin jacket further improved the insulation. The enzyme column (inner dia-
meter
¥
4 mm), constructed of Delrin, was held tightly against the
inner terminals of the copper core. Short pieces of well-insulated gold capillaries
(outer diameter/inner diameter: 0.3/0.2 mm) were placed next to the enzyme
column as temperature-sensitive elements. Microbead thermistors were moun-
ted on the capillaries with a heat-conducting epoxy. Two types of mini system
has been constructed as discussed below.
¥
length: 3
¥
2.2.1
Plastic Chip Sensor
The chip sensor (27
6 mm) was constructed of Plexiglas (see Fig. 3). The
rectangular enzyme cell (5
¥
7
¥
¥
3
¥
0.5 mm) and the inlet and outlet parts were
A
B
Fig. 3.
Schematic diagram of a microcolumn ET sensor (see text for detailed description)
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