Editing Security alarm (section)

=== MEMS Accelerometer ===
MEMS technology is an electromagnetic device that is created using [[photolithography]], incision and ionian implantation. This produces a very compact and small device. In this device, in addition to the mechanical system, there are electronic circuits for control, acquisition and conditioning of the signal able to sense the environment.<ref>{{Cite book |last1=De Astis |first1=Vincenzo |title="Manuale delle tecnologie di sicurezza" |last2=Dischi |first2=Franco |publisher=Assosicurezza |year=2019 |location=Italy |pages=133–134 |language=it}}</ref>

MEMS accelerometer can be divided into two groups, piezoresistive and capacitive-based accelerometers. The former consists of a 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.<ref>{{Cite journal |last=Albarbar |first=Alhussein |date=2008 |title=Suitability of MEMS Accelerometers for Condition Monitoring: An experimental study |url=https://www.mdpi.com/1424-8220/8/2/784/pdf |journal= Sensors|volume=8 |issue=2 |pages=784–799|doi=10.3390/s8020784 |pmid=27879734 |pmc=3672998 |bibcode=2008Senso...8..784A |doi-access=free }}</ref>

On the contrary, capacitive-based accelerometers, also known as vibration sensors, rely on a change in electrical capacitance in response to acceleration.<ref>{{Cite book |last1=Venkatanarayanan |first1=A. |last2=Spain |first2=E. |title=Comprehensive Materials Processing |chapter=Review of Recent Developments in Sensing Materials |date=2014 |chapter-url=https://www.sciencedirect.com/science/article/pii/B9780080965321013030 |pages=47–101 |doi=10.1016/B978-0-08-096532-1.01303-0 |isbn=9780080965338 }}</ref>

==== 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' incorporations evolved from a single, stand-alone device to the integrated inertial motion units that are available today.<ref>{{Cite book |last1=De Astis |first1=Vincenzo |title=Manuale delle tecnologie di sicurezza |last2=Dischi |first2=Franco |publisher=Assosicurezza |year=2019 |edition=2nd |location=Italy |pages=134–135 |language=it}}</ref>

This technology uses a variety of transduction mechanisms to detect the displacement. They include capacitive, piezoresistive, thermal, optical, piezoelectric and tunneling.<ref>{{Cite book |last1=Rasras |first1=Mahmoud |title=MEMS Accelerometers |last2=Elfadel |first2=Ibrahim M. |last3=Duong Ngo |first3=Ha |publisher=MDPI |year=2019 |isbn=978-3-03897-415-4 |location=Abu Dhabi, UAE |pages=1–2, 12, 4–6 |language=en}}</ref>

==== Applications ====
[[File:Sioux MEMS 3D Pro2.jpg|thumb|Fence protected by a device which uses MEMS technology to detect intruders]]
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 accelerometers is the linear frequency response to DC to about 500&nbsp;Hz, and this capability offers an improvement in measuring [[ground motion]] at lower-frequency band.<ref>{{Cite journal |last1=Aizawa |first1=Takao |last2=Matsuoka |first2=Toshi |last3=Kimura |first3=Toshinori |last4=Takeda |first4=Tetsuya |date=2008 |title=Application of MEMS accelerometer to geophysics |url=https://www.researchgate.net/publication/43195901 |journal=International Journal of the JRCM |volume=4}}</ref>

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.<ref>{{Cite journal |last1=Albarbar |first1=Alhussein |last2=Mekid |first2=Samir |last3=Starr |first3=Andrew |last4=Pietruszkiewicz |first4=Robert |date=2008 |title=Suitability of MEMS Accelerometers for Condition Monitoring: An experimental study |url=https://www.mdpi.com/1424-8220/8/2/784/pdf |journal= Sensors|volume=8 |issue=2 |pages=784–799 |doi=10.3390/s8020784 |pmid=27879734 |pmc=3672998 |bibcode=2008Senso...8..784A |doi-access=free }}</ref>

Moving to the [[arms industry|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 them to constantly verify that the positioning of the sensor, based on MEMS accelerometer, remains unaltered from the installation one.

MEMS accelerometers’ significant advantages also stem from their small size and high measurement frequency; additionally, they can be integrated with multiple sensors with different functions.<ref>{{Cite journal |last1=Niu |first1=Weimeng |last2=Fang |first2=Liqing |last3=Xu |first3=Lei |last4=Li |first4=Xu |last5=Huo |first5=Ruikun |last6=Guo |first6=Deqing |last7=Qi |first7=Ziyuan |date=2018 |title=Summary of Research Status and Application of MEMS Accelerometers |url= |journal=Army Engineering University Shijiazhuang Campus, Shijiazhuang.}}</ref>