5 - MEMS devices

Suspended mass

TThe working principe of the angular rate sensor is based on the Coriolis force, affecting a moving object in a rotating system. Structures contain a couple of magnetic, electrostatic or piezoelectric driven moving part, and a couple of sensors (capacitive or piezoelectric) perpendicular to the moving direction. When the unit rotates, sensors are moving due to Coriolis force, producing voltage or capacity change proportional to the rotation (W).

Rotating plate sensor

Tuning fork sensor

In thermodynamic tilt angle sensor a heated air bubble stays always in an opposite direction of gravitation. Since the angle between the vector of gravitation and the sensor plane changes during inclination, it can be sensed through the deformation of the air bubble. Similar to the accelerometer, there are heat sensors on both sides of the heater element for signal pickup. The temperature difference is changing during inclination. The animation shows an 1-D inclinometer, but using two couples of heat sensors a 2-D inclinometer can be built.

Silicon-based microphones are produced by bulk microfabrication technologies. These subminiature microphones (membrane diameter = 1mm) are based on capacitive voltage modulation. One of the realized structures can be seen on the animation. To explore, how does it work, klick on the sine wave generator!

Silicon-based microphones are produced by bulk microfabrication technologies. These subminiature microphones (membrane diameter = 1mm) are based on capacitive voltage modulation. One of the realized structures can be seen on the animation. To explore, how does it work, klick on the sine wave generator!

Mass air flow sensor

In the aerodynamic flow sensor a hot air bubble is generated by a heater filament. The flow-rate of a fluid (or gas) can be sensed through the deformation of the air bubble. There are temperature sensors on both sides of the heater filament for signal pickup. The temperature is changing proportional to the flow-rate.

Aerodynamic flow sensor

In the aerodynamic flow sensor a hot air bubble is generated by a heater filament. The flow-rate of a fluid (or gas) can be sensed through the deformation of the air bubble. There are temperature sensors on both sides of the heater filament for signal pickup. The temperature is changing proportional to the flow-rate.

Optical fiber based flow sensor

The optical fiber based flow sensor consists of an optical reflective mirror attached to unique cantilever designs that bend due to a mass flow. The light is modulated using a Fabry-Perot interferometry technique to determine the mirror separation with respect to the end tip of the optical fiber, which separation changes depending on mass flow, due to the bending of cantilever design. The sensor is not affected by electromagnetic interference and does not require electrical currents to sense, i.e. it is perfectly suited for biomedical and low mass-flow sensing.