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1.3 Miniaturized Systems with Microoptics and Micromechanics 19

Bow-tie antenna

Electrostatic
500 actuator
mm 1.6 10mm
Gap spacing (mm) 0.8 Measured gap
Springs 1.4
1.2
Glass substrate 1
0.6
0.4
0.2
0
80
0 40 Calculated gap 120 160
Applied voltage (V)
Fig. 1.23. A bow–tie probe with an actuator driven by electrostatic force is fabri-
cated to provide a narrow gap that enhances the intensity of the near field. Reprinted
from [1.46] with permission by M. Esashi, Tohoku University, Japan

waste
Optical mixer

Sample

Reagent Microchannel
Fig. 1.24. Conceptual drawing of the future micrototal analysis system (µ-TAS)
[1.50]

and intersectingchannels [1.49] to induce chaotic behavior of a flow have
been fabricated. An optically driven micromixer [1.50] has been proposed to
stir a liquid directly, which is described in detail in Chap. 4. Highly sensitive
detection methods [1.51] and high-performance micropumps [1.52] are also
important because of the reaction between small liquids, as well as to drive
liquids in microchannels.
Optical inspection of a human body is also a useful method for minimally
invasive diagnosis and treatment. Figure 1.25 shows the microconfocal opti-
cal scanningmicroscope (m-COSM) [1.53]. The probe, 2.4 mm in diameter,
consists of a 2-D electrostatic scanner which is placed in front of the end of
the optical fiber. Light reflected by the tissue is collected by the same objec-
tive lens and reflected back into the same optical fiber. The field of view is
100 µm × 100 µm and the resolution is 1 µm with an image feed speed of 4
frames s −1 .