Ma. Chan et al., A MICROMACHINED PRESSURE SENSOR WITH FIBEROPTIC INTERFEROMETRIC READOUT, Sensors and actuators. A, Physical, 43(1-3), 1994, pp. 196-201
A high sensitivity, batch fabricated, fiber-optic pressure sensor has
been fabricated using silicon micromachining technology. The transduce
r consists of a fiber positioning v-groove, a 45-degrees stationary mi
rror and a silicon membrane, micromachined in silicon by anisotropic e
tching in KOH solution, and a single mode optical fiber. The membrane
and optical fiber end form a Fabry-Perot cavity whose length varies wi
th pressure. The generated optical interference fringes are used to de
tect and measure the change in membrane deflection. Pressure range of
operation is dictated by the thickness, size and material of the membr
ane. The sensor described here was designed for low pressure range (0-
25 mm Hg) applications. Temperature sensitivity and stability problems
which are commonly encountered with currently available piezoresistiv
e and capacitive pressure sensors are significantly reduced by the inh
erent differential nature of interferometric measurement and the use o
f all silicon construction. The fabrication, packaging and testing of
the sensor are described in this paper. The performance of the sensor
was evaluated and found to compare favorably with theoretical predicti
ons.