Editing Piezoelectricity (section)

===Potential applications===
In 2015, Cambridge University researchers working in conjunction with researchers from the National Physical Laboratory and Cambridge-based dielectric antenna company Antenova Ltd, using thin films of piezoelectric materials found that at a certain frequency, these materials become not only efficient resonators, but efficient radiators as well, meaning that they can potentially be used as antennas. The researchers found that by subjecting the piezoelectric thin films to an asymmetric excitation, the symmetry of the system is similarly broken, resulting in a corresponding symmetry breaking of the electric field, and the generation of electromagnetic radiation.<ref>{{Cite journal|first1=Dhiraj|last1=Sinha|first2=Gehan|last2=Amaratunga|title=Electromagnetic Radiation Under Explicit symmetry Breaking|journal=Physical Review Letters|volume=114|issue=14|page=147701|year=2015|doi=10.1103/physrevlett.114.147701|pmid=25910163|bibcode = 2015PhRvL.114n7701S |url=https://zenodo.org/record/1038659}}</ref><ref>{{cite web|title=New understanding of electromagnetism could enable 'antennas on a chip'|url=http://www.cam.ac.uk/research/news/new-understanding-of-electromagnetism-could-enable-antennas-on-a-chip|website=cam.ac.uk|url-status=live|archive-url=https://web.archive.org/web/20160304113152/http://www.cam.ac.uk/research/news/new-understanding-of-electromagnetism-could-enable-antennas-on-a-chip|archive-date=2016-03-04|date=2015-04-09}}</ref>

Several attempts at the macro-scale application of the piezoelectric technology have emerged<ref>{{cite journal|last1=Takefuji|first1=Y.|title=And if public transport does not consume more of energy?|journal=Le Rail|date=April 2008|pages=31–33|url=http://neuro.sfc.keio.ac.jp/publications/pdf/rail.pdf|access-date=2018-12-15|archive-date=2021-01-15|archive-url=https://web.archive.org/web/20210115165450/http://neuro.sfc.keio.ac.jp/publications/pdf/rail.pdf|url-status=dead}}</ref><ref>{{Cite conference|last1=Takefuji|first1=Y.|title=Known and unknown phenomena of nonlinear behaviors in the power harvesting mat and the transverse wave speaker|conference=international symposium on nonlinear theory and its applications|date=September 2008|url=http://neuro.sfc.keio.ac.jp/publications/pdf/nolta.pdf|access-date=2018-12-15|archive-date=2020-10-21|archive-url=https://web.archive.org/web/20201021073953/http://neuro.sfc.keio.ac.jp/publications/pdf/nolta.pdf|url-status=dead}}</ref> to harvest kinetic energy from walking pedestrians.

In this case, locating high traffic areas is critical for optimization of the energy harvesting efficiency, as well as the orientation of the tile pavement significantly affects the total amount of the harvested energy.<ref>{{cite journal |last1=Deutz |first1=D.B. |last2=Pascoe |first2=J.-A. |last3=van der Zwaag |first3=S. |last4=de Leeuw |first4=D.M. |last5=Groen |first5=P.|title=Analysis and experimental validation of the figure of merit for piezoelectric energy harvesters |journal=Materials Horizons |volume=5 |date=2018 |issue=3 |pages=444–453 |doi=10.1039/c8mh00097b |url=http://resolver.tudelft.nl/uuid:3ebce2f3-e2d8-433c-bbcd-684e0835c14b |hdl=10044/1/60608 |hdl-access=free }}</ref> A density flow evaluation is recommended to qualitatively evaluate the piezoelectric power harvesting potential of the considered area based on the number of pedestrian crossings per unit time.<ref name="ReferenceA">{{cite journal|last1=Li|first1=Xiaofeng|last2=Strezov|first2=Vladimir|year=2014|title=Modelling piezoelectric energy harvesting potential in an educational building|url=http://www.researchonline.mq.edu.au/vital/access/services/Download/mq:33352/DS01|journal=Energy Conversion and Management|volume=85|pages=435–442|doi=10.1016/j.enconman.2014.05.096|bibcode=2014ECM....85..435L }}</ref> In X. Li's study, the potential application of a commercial piezoelectric energy harvester in a central hub building at Macquarie University in Sydney, Australia is examined and discussed. Optimization of the piezoelectric tile deployment is presented according to the frequency of pedestrian mobility and a model is developed where 3.1% of the total floor area with the highest pedestrian mobility is paved with piezoelectric tiles. The modelling results indicate that the total annual energy harvesting potential for the proposed optimized tile pavement model is estimated at 1.1&nbsp;MWh/year, which would be sufficient to meet close to 0.5% of the annual energy needs of the building.<ref name="ReferenceA"/> In Israel, there is a company which has installed piezoelectric materials under a busy highway. The energy generated is enough to power street lights, billboards, and signs.{{citation needed|date=June 2016}}

Tire company [[Goodyear Tire and Rubber Company|Goodyear]] has plans to develop an electricity generating tire which has piezoelectric material lined inside it. As the tire moves, it deforms and thus electricity is generated.<ref>{{cite magazine|title=Goodyear Is Trying to Make an Electricity-Generating Tire|url=https://www.wired.com/2015/03/goodyear-trying-make-electricity-generating-tire/|magazine=WIRED|access-date=14 June 2016|url-status=live|archive-url=https://web.archive.org/web/20160511070323/http://www.wired.com/2015/03/goodyear-trying-make-electricity-generating-tire|archive-date=11 May 2016|date=2015-03-12}}</ref>

The efficiency of a hybrid [[photovoltaic cell]] that contains piezoelectric materials can be increased simply by placing it near a source of ambient noise or vibration. The effect was demonstrated with organic cells using [[zinc oxide]] nanotubes. The electricity generated by the piezoelectric effect itself is a negligible percentage of the overall output. Sound levels as low as 75 decibels improved efficiency by up to 50%. Efficiency peaked at 10&nbsp;kHz, the resonant frequency of the nanotubes. The electrical field set up by the vibrating nanotubes interacts with electrons migrating from the organic polymer layer. This process decreases the likelihood of recombination, in which electrons are energized but settle back into a hole instead of migrating to the electron-accepting ZnO layer.<ref>{{cite web |url=http://www.gizmag.com/vibration-sound-efficient-hybrid-solar-cell-arrays/29679/ |title=Good vibrations lead to efficient excitations in hybrid solar cells |publisher=Gizmag.com |access-date=2013-11-11 |author=Heidi Hoopes |date=November 8, 2013 |url-status=live |archive-url=https://web.archive.org/web/20131111193548/http://www.gizmag.com/vibration-sound-efficient-hybrid-solar-cell-arrays/29679/ |archive-date=November 11, 2013 }}</ref><ref>{{Cite journal | last1 = Shoaee | first1 = S. | last2 = Briscoe | first2 = J. | last3 = Durrant | first3 = J. R. | last4 = Dunn | first4 = S. | title = Acoustic Enhancement of Polymer/ZnO Nanorod Photovoltaic Device Performance | doi = 10.1002/adma.201303304 | journal = Advanced Materials | volume = 26 | issue = 2 | pages = 263–268 | year = 2013 | pmid = 24194369 | url = http://qmro.qmul.ac.uk/xmlui/handle/123456789/12456 }}</ref>