Editing Light-emitting diode (section)

=== Other applications ===
[[file:LED Costume by Beo Beyond.jpg|thumb|LED costume for stage performers]]
[[file:Digitally printed LED wallpaper Dolomites.jpg |thumb|LED wallpaper by Meystyle]]
[[file:LED screen behind Tsach Zimroni in Tel Aviv Israel.jpg|thumb|A large LED display behind a [[disc jockey]]]]
[[file:LED Digital Display.jpg|thumb|[[Seven-segment display]] that can display four digits and points]]
[[file:LED panel and plants.jpg|thumb|LED panel light source used in an early experiment on [[potato]] growth during Shuttle mission [[STS-73]] to investigate the potential for growing food on future long duration missions]]

The light from LEDs can be modulated very quickly so they are used extensively in [[optical fiber]] and [[free space optics]] communications. This includes [[remote control]]s, such as for television sets, where infrared LEDs are often used. [[Opto-isolator]]s use an LED combined with a [[photodiode]] or [[phototransistor]] to provide a signal path with electrical isolation between two circuits. This is especially useful in medical equipment where the signals from a low-voltage [[sensor]] circuit (usually battery-powered) in contact with a living organism must be electrically isolated from any possible electrical failure in a recording or monitoring device operating at potentially dangerous voltages. An optoisolator also lets information be transferred between circuits that do not share a common ground potential.

Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. The Nintendo [[Wii]]'s sensor bar uses infrared LEDs. [[Pulse oximeter]]s use them for measuring [[oxygen saturation]]. Some flatbed scanners use arrays of RGB LEDs rather than the typical [[cold-cathode fluorescent lamp]] as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light.

Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a [[touchscreen]] that registers reflected light from a finger or [[stylus]].<ref>{{cite journal |author1=Dietz, P. H. |author2=Yerazunis, W. S. |author3=Leigh, D. L. |title=Very Low-Cost Sensing and Communication Using Bidirectional LEDs |year=2004 |url=http://www.merl.com/publications/TR2003-035/}}</ref> Many materials and biological systems are sensitive to, or dependent on, light. [[Grow lights]] use LEDs to increase [[photosynthesis]] in [[plant]]s,<ref>{{cite journal |author1=Goins, G. D. |author2=Yorio, N. C. |author3=Sanwo, M. M. |author4=Brown, C. S. |title=Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting |journal=Journal of Experimental Botany |year=1997 |volume=48 |issue=7 |pages=1407–1413 |doi=10.1093/jxb/48.7.1407 |pmid=11541074|doi-access=free }}</ref> and bacteria and viruses can be removed from water and other substances using UV LEDs for [[Sterilization (microbiology)|sterilization]].<ref name="water sterilization" /> LEDs of certain wavelengths have also been used for [[light therapy]] treatment of [[neonatal jaundice]] and [[acne]].<ref>{{cite book |last1=Li |first1=Jinmin |last2=Wang |first2=Junxi |last3=Yi |first3=Xiaoyan |last4=Liu |first4=Zhiqiang |last5=Wei |first5=Tongbo |last6=Yan |first6=Jianchang |last7=Xue |first7=Bin |title=III-Nitrides Light Emitting Diodes: Technology and Applications |date=31 August 2020 |publisher=Springer Nature |isbn=978-981-15-7949-3 |page=248 |url=https://books.google.com/books?id=Smn6DwAAQBAJ&pg=PA248 |language=en}}</ref>

UV LEDs, with spectra range of 220&nbsp;nm to 395&nbsp;nm, have other applications, such as [[water purification|water]]/[[air purification|air]] purification, surface disinfection, glue curing, free-space [[non-line-of-sight communication]], high performance liquid chromatography, UV curing dye printing, [[phototherapy]] (295nm [[Vitamin D]], 308nm [[Excimer lamp]] or laser replacement), medical/ analytical instrumentation, and DNA absorption.<ref name=":1" /><ref>{{Cite book|last1=Gaska|first1=R.|last2=Shur|first2=M. S.|last3=Zhang|first3=J.|title=2006 8th International Conference on Solid-State and Integrated Circuit Technology Proceedings |chapter=Physics and Applications of Deep UV LEDs |date=October 2006|pages=842–844|doi=10.1109/ICSICT.2006.306525|isbn=1-4244-0160-7|s2cid=17258357}}</ref>

LEDs have also been used as a medium-quality [[voltage reference]] in electronic circuits. The forward voltage drop (about 1.7&nbsp;V for a red LED or 1.2V for an infrared) can be used instead of a [[Zener diode]] in low-voltage regulators. Red LEDs have the flattest I/V curve above the knee. Nitride-based LEDs have a fairly steep I/V curve and are useless for this purpose. Although LED forward voltage is far more current-dependent than a Zener diode, Zener diodes with breakdown voltages below 3&nbsp;V are not widely available.

The progressive miniaturization of low-voltage lighting technology, such as LEDs and OLEDs, suitable to incorporate into low-thickness materials has fostered experimentation in combining light sources and wall covering surfaces for interior walls in the form of [[LED wallpaper]].