thickness and weight of 0,040 grams. In this small device, in addition to the mechanical system, there are electronic circuits for control, acquisition and conditioning of the signal able to sense the environment. MEMS accelerometer can be divided into two groups: Piezoresistive and capacitive based accelerometers. The first group consist of single degree of freedom system of a mass suspended by a spring, they also have a beam with a proof mass at the beam’s tip and a Piezoresistive patch on the beam web. On the contrary, capacitive based accelerometers, also known as vibration sensors, rely on a change in electrical capacitance in response to acceleration. Operating principle The current technology allows to realize suspended silicon structures that are attached to the substrate in some points called anchors, and that constitute the sensitive mass of the accelerometer MEMS. These structures are free to move in the direction of the acceleration detected, they constitute the mobile reinforcement of a pair of capacitors connected to the half bridge. In this way the acquired signals are amplified, filtered and converted in digital signals with the supervision of specific control circuits. MEMS' incorporation’s evolved from a single, stand-alone device to the integrated 6-axis and 9-axis inertial motion units that are available on the market today. This technology uses a variety of transduction mechanism to detect the displacement. They include capacitive, piezoresistive, thermal, optical, piezoelectric and tunneling. Applications In the last decades many technological progresses have been made in this area and MEMS accelerometers are used in high-reliability environments and are starting to replace other established technologies. MEMS accelerometer can be applied as a sensor in the earthquake disaster prevention since one of the main characteristics of MEMS accelerometer is the linear frequency response to DC to about 500Hz and this capability offers an improvement in measuring ground motion at lower frequency band. Another practical application of MEMS accelerometers is in machine condition monitoring to reduce machines’ maintenance. Wireless and embedded technologies such as Micro-electro Mechanical system sensors offer a wireless smart vibration measurement of machine’s condition. Moving to the defence field, it can be applied in fence-mounted intrusion detection systems. Since MEMS sensors are able to work in a wide temperature range, they can prevent intrusions in outdoors and very spread-off perimeters. Properties An advantage offered by MEMS Accelerometers is the ability to measure static accelerations, such as acceleration due to gravity. This enables