Photodegradation of melanin thin films by UV lithography

Effect of ambient humidity on the photodegradation of melanin is investigated using an interferometric technique to fabricate gratings on thin films. A low power 355 nm diode laser is used to fabricate gratings on melanin thin films, while a 1 mW He-Ne laser is used to probe grating formation. Effects at several different UV intensities, ranging from 10 mW to 30 mW, and ambient humidities, ranging from 13% to 93%, are investigated on melanin thin films of two different thicknesses; 22 nm and 40nm. It is found that humidity has a great effect on the photodegradation of melanin. It is also found that existing gratings on melanin thin films can be enhanced by raising ambient humidity. These results have implications in the biological evolution of many mammals; as well as implications in fabrication and effective lifetime of organic electronics. The interferometric technique used shows great promise for fabricating grating to analyze photodegradation of different biomolecules under varying conditions. A simple mathematical model is developed to help explain the contribution of light intensity and ambient humidity to the photodegradation of melanin.nage.