'''Fluctuation-enhanced sensing''' ('''FES''') is a specific type of chemical or biological sensing where the stochastic component, [[Noise (electronics)|''noise'']], of the sensor signal is analyzed.<ref>{{cite book | title = 2011 21st International Conference on Noise and Fluctuations | author1 = Robert Mingesz | author2 = Zoltan Gingl | author3 = Akos Kukovecz | author4 = Zoltan Konya | author5 = Krisztian Kordas | author6 = Hannu Moilanen | doi = 10.1109/ICNF.2011.5994350 | chapter = Compact USB measurement and analysis system for real-time fluctuation enhanced sensing | year = 2011 | isbn = 978-1-4577-0189-4 | pages = 385–388 | volume = 21 | issue = 12 | arxiv = 1102.2446 | s2cid = 41705045 }}</ref> The stages following the sensor in a FES system typically contain filters and preamplifier(s) to extract and amplify the stochastic signal components, which are usually microscopic temporal fluctuations that are orders of magnitude weaker than the sensor signal. Then selected statistical properties of the amplified [[Noise (electronics)|''noise'']] are analyzed, and a corresponding pattern is generated as the stochastic fingerprint of the sensed agent. Often the [[power density]] spectrum of the stochastic signal is used as output pattern however FES has been proven effective with more advanced methods, too, such as [[higher-order statistics]].
==History==
During the 1990s, several authors (for example, Bruno Neri and coworkers, Peter Gottwald and Bela Szentpali) had proposed using the spectrum of measured noise to obtain information about ambient chemical conditions. However, the first systematic proposal for a generic [[electronic nose]] utilizing chemical sensors in FES mode, and the related mathematical analysis with experimental demonstration, were carried out only in 1999 by [[Laszlo B. Kish]], Robert Vajtai and [[Claes-Göran Granqvist|C.G. Granqvist]]<ref>{{cite journal |url = http://www.ece.tamu.edu/%7Enoise/research_files/noise_nose_sensor_act.pdf |last1=Kish |first1=L.B. |last2=Vajtai |first2=R. |last3=Granqvist |first3=C.G. | name-list-style=vanc |title=Extracting information from noise spectra of chemical sensors: single sensor electronic noses and tongues |journal=Sensors and Actuators B: Chemical |date=November 2000 |volume=71 |issue=1–2 |pages=55–59 |doi=10.1016/S0925-4005(00)00586-4 |bibcode=2000SeAcB..71...55K }}</ref> at [[Uppsala University]]. The name "fluctuation-enhanced sensing" was created by John Audia ([[United States Navy]]), in 2001, after learning about the published scheme. In 2003, Alexander Vidybida from [http://www.bitp.kiev.ua/index.php?lang=en Bogolyubov Institute for Theoretical Physics] of the [[National Academy of Sciences]] of Ukraine has proven mathematically that adsorption–desorption fluctuations during odor primary reception can be used for improving selectivity. <ref>{{cite journal | last1 = Vidybida | first1 = A. K. | year = 2003 | title = Adsorption–desorption noise can be used for improving selectivity | journal = Sensors and Actuators A:Physical | volume = 107 | issue = 3| pages = 233–237 | arxiv=physics/0212088 |doi = 10.1016/S0924-4247(03)00355-8 | bibcode = 2003SeAcA.107..233V | s2cid = 9340741 }}</ref>
During the years, FES has been developed and demonstrated in many studies with various types of sensors and agents in chemical and biological systems. Bacteria have also been detected and identified by FES, either by their odor in air,<ref>{{cite journal | arxiv = 0901.3100 | title = Fluctuation-enhanced sensing of bacterial odors | author1 = Hung-Chih Chang | author2 = L.B. Kish | author3 = M.D. King | author4 = C. Kwan | journal = Sensors and Actuators B: Chemical | year = 2009 | volume = 142 | issue = 2 | page = 429 | doi = 10.1016/j.snb.2009.04.005 | bibcode = 2009SeAcB.142..429C }}</ref><ref>{{cite journal |last1=Chang |first1=Hung-Chih |last2=Kish |first2=Laszlo |last3=King |first3=Maria |last4=Kwan |first4=Chiman |title=Binary fingerprints at fluctuation-enhanced sensing |journal=Sensors |date=5 January 2010 |volume=10 |issue=1 |pages=361–373 |doi=10.3390/s100100361 |doi-access=free|pmid=22315545 |pmc=3270846|arxiv=0912.5212 |bibcode=2010Senso..10..361C }}</ref> or by the "[[Sensing of phage-triggered ion cascades|SEPTIC]]" method in liquid phase.
In the period of 2006–2009 [http://www.signalpro.net Signal Processing Inc] (Chiman Kwan) developed a portable FES device in collaboration with [[Texas A&M University]] (Laszlo B. Kish) and [[University of Szeged]] (Zoltan Gingl and [[Peter Heszler]]). Efforts to explore [[higher-order statistics]] for FES purposes were led by [[Janusz Smulko]].<ref>{{cite book|journal=SPIE Proceedings | title = Noise and Fluctuations in Circuits, Devices, and Materials | author1 = L.B. Kish | author2 = G. Schmera | author3 = C. Kwan | author4 = J. Smulko | author5 = P. Heszler | author6 = C.G. Granqvist | chapter = Fluctuation-enhanced sensing | editor4-first = Michael B. | editor4-last = Weissman | editor3-first = Carmine | editor3-last = Ciofi | editor2-first = Lode K. | editor2-last = Vandamme | editor1-first = Massimo | editor1-last = MacUcci | doi = 10.1117/12.726838 | year = 2007 | volume = 6600 | pages = 66000V | arxiv = 0705.0160 | bibcode = 2007SPIE.6600E..0VK | s2cid = 119601788 }}</ref> SPAWAR ([[United States Navy]]) related FES projects were led by Gabor Schmera (see the [[United States Navy|US Navy]] patent site below).
==References==
{{Reflist}}
==External links== * [http://noise.ece.tamu.edu/research_files/research_FES.htm FES website at Texas A&M University.] * [https://web.archive.org/web/20110413023927/http://www.public.navy.mil/spawar/Pacific/TechTransfer/ProductsServices/Pages/FluctuationEnhancedChemicalSense.aspx Summary of three FES-related patents on the US Navy website.]
<!--- Categories ---> [[Category:Biological techniques and tools]] [[Category:Laboratory equipment]] [[Category:Olfaction]]