Page 276 - MEMS Mechanical Sensors

Index 265

hysteresis, 104 macroscopic, 185
soft, 103 PZT, 186
Nonthermal time of flight flow sensors, sensing element SEM photograph, 187
239–41 See also Accelerometers
electrochemical, 240–41 Piezoelectric cantilevers, 163
electrohydrodynamic, 239–40 Piezoelectricity, 89–92
See also Flow sensors anisotropic nature, 90
effect illustration, 89
O material properties, 91
voltage coefficient, 90
Open loop accelerometers, 176–77
defined, 176 Piezoelectric microphones, 144
illustrated, 177 Piezoresistive accelerometers, 181–82
cross-sectional view, 181
See also Accelerometers
Optical flow measurement, 245–47 defined, 181
integrated, 192
fluid velocity, 245–46
multiphase flow detection, 246–47 See also Accelerometers
particle detection and counting, 246 Piezoresistive microphones, 144
Optical techniques, 94–97 Piezoresistive pressure sensors, 132–37
commercial availability, 133
frequency, 96–97
intensity, 94–95 cross-section, 132
phase, 95 dual beam configuration, 136
fusion bonded, 135
polarization, 97
spatial position, 96 plan view, 132
wavelength, 96 temperature cross-sensitivity, 134
See also Mechanical transduction See also Pressure sensors
Piezoresistivity, 85–89
techniques
Optical torque sensors, 159–60 defined, 85
modified moiré fringe method, 160 in silicon, 88
optoelectronic, 160 Pitot tube arrangement, 116
Plasma enhanced CVD (PECVD), 13
torsion angle measurement, 160
defined, 13
silicon nitride, 15
P
See also Chemical vapor deposition (CVD)
Packaging, 57–81 Plastic packages, 59
ceramic, 58 Poisson’s ratio, 86, 87
die attachment methods, 63–64 Polarization, 97
electrical interconnects, 60–63 Polysilicon, 5
first order, 67 deposition, 13
introduction, 57 epipoly, 14
low-cost approach, 77 LPCVD, 13
metal, 59 piezoresistive, 88
plastic, 59 See also Silicon (Si)
processes, 59–66 Porous silicon, 35
requirements, 66 Pressure difference flow sensors, 229–32
sealing techniques, 65–66 advantages/disadvantages, 232
second order, 67 capacitive pressure sensing principles, 230
standard IC, 58–59 defined, 229–30
wafer level, 67–68 schematics, 231
Periodic flapping motion, 242–43 thermal flow sensors as, 218
Phase, 95 velocity, 231
Photoresists, 19 See also Flow sensors
Piezoelectric accelerometers, 185–86
design, 187