Sensor - The Electronic Nose Artificial Olfaction Technology - page 62

2.10 MEMS and Fabrication of MEMS Sensor

Micro-Electro-Mechanical Systems (MEMS) is the integration of mechanical
elements, sensors, actuators, and electronics on a common silicon substrate
through micro-fabrication technology. Electronics are fabricated using integrated
circuit (IC) process and the micromechanical components are fabricated using
compatible micromachining. Microelectronic-integrated circuits can be thought of
as the ''brains'' of a system.
In order to solve the measurement problem in the harsh environment, a sensor
has been developed, which can be used under high temperature, high pressure, and
is able to endure instantaneous ultra high environmental impact. Based on the
MEMS and IC technology, the sensor's sensitive element was fabricated and
constituted by silicon substrate. The experimental results show that the developed
sensor has good performances under critical circumstances and is able to endure
instantaneous

ultra high temperature/pressure/flow impact, which meets the

requirements of modern industry, such as aviation, oil, engine, etc.
Sensors made using MEMS are better than their conventional counterparts
because they are:

• Smaller in size
• Have lower power consumption
• More sensitive to input variations
• Cheaper due to mass production
• Less invasive than larger devices.

The sensor is fabricated with a series of standard silicon processing techniques.
Silicon is the standard substrate material for IC fabrication and, hence, the most
common substrate material in fabrication in general. A wafer is a thin slice of a
silicon crystal (semiconductor material), used in the fabrication of IC (i.e., sensor)
and other micro devices. The wafer serves as the substrate for microelectronic
devices built in and over the wafer and undergoes many micro fabrication process
steps such as doping or ion implantation, etching, deposition of various materials,
and photolithographic patterning [ 14 ].

MEMS applications:

• Accelerometers,
• silicon-based Piezo-resistive pressure sensors,
• capacitive pressure sensors,
• digital micro mirror arrays,
• chemical/biosensors and gas sensors,
• micro resonators,
• infrared detectors,
• focal plane arrays for earth observations,
• space science,
• missile defense applications,