On April 1, 2002, organic light-emitting diodes gained popularity in the scientific community with their more practical form released at Ames Laboratory. “Scientists at the U.S. Department of Energy's Ames Laboratory, in collaboration with scientists at the University of Michigan in Ann Arbor, have developed and demonstrated a new fluorescence-based chemical sensor that is more compact, versatile and less expensive than the existing technology of this type. The new sensor shows promise for a myriad of potential applications, such as monitoring oxygen, inorganic gases, volatile organic compounds, biochemical compounds and biological organisms. » (Johnston). The Ames Lab was a driving force in OLED research and ultimately produced an effective model. . Generally, OLEDs comprise a layer of organic materials placed between an anode and a cathode, all deposited on a substrate. In the organic layer, there is an emissive layer, which easily emits electrons, and a conductive layer, in which electrons are removed. OLEDs work by electrophosphorescence and therefore have a similar process to the one we covered; a voltage excites one species, which transfers to a different spin orbital, then drops to the ground state to emit a photon. First, a voltage is applied across the OLED, causing a current of electrons to flow from the cathode to the anode and through the organic layer. The cathode donates electrons to the emissive layer of organic molecules. The anode removes electrons from the conductive layer of organic molecules, creating “holes” or gaps. At the boundary between the emissive and conductive layers, the electrons find the “holes”. The electrons fill the holes by falling into a different spin state, corresponding to the atom that is missing an electron. The electron then...... middle of paper ....... Optical sensors and multisensor arrays containing thin-film electroluminescent devices. Iowa State University Research Foundation, Inc., assignee. US Patent 6,331,438 B1. December 18, 2001. Print. Freudenrich, Craig. "HowStuffWorks "How OLEDs Work"" HowStuffWorks "Electronics" How it works. Internet. November 28, 2011. “Future Technologies.” Michigan State University. EST. 1855. East Lansing, Michigan USA. Michigan State University. Internet. November 27, 2011. .Johnston, Saren. “New standard in sensor technology. » EurekAlert! - Scientific news. Ames Laboratory. Internet. November 29, 2011. “Low-cost OLED sensors for 24/7 protection.” » Ameslab.gov. Iowa State University. Internet. November 27. 2011. .