LEDs and biomedical applications Tekst og Streger i 100% farve – Baggrund i 90% Transparent. LEDs and biomedical applications Aikaterini Argyraki, Paul Michael Petersen DTU Fotonik, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark Optimal illuminant for visual inspection of veins In the present study we provide empirical evidence and demonstrate statistically that white illumination settings can affect the human ability to identify veins in the inner hand vasculature. It is shown that the ability to identify veins can, on average, be increased up to 24% when white illumination settings that do not resemble incandescent light are applied. The illuminance reported together with the effect of white illumination settings on direct visual perception of biosamples are relevant for clinical investigations during the night (not disturbing the circadian rhythm). Comparison of UVB and UVC irradiation disinfection efficacies on Pseudomonas Aeruginosa biofilm In the present study the inactivation rate was studied as a function of dose for 24h grown biofilms. The dose was ramped from 72J/m2 to 10000J/m2. It was shown that UVB irradiation was more effective than UVC irradiation in inactivating P. aeruginosa biofilms. No colony forming units (CFU) were observed for the UVB treated biofilms when the dose was 10000 J/m2 (CFU in control sample: 7.5 x 104). UVB irradiation at a dose of 20040J/m2 on mature biofilms (72h grown) resulted in a 3.9 log inactivation. The fact that the wavelength of 296nm exists in daylight and has such disinfection ability on biofilms gives new perspectives for applications within disinfection at hospitals and disinfection procedures during root canal treatment. Aikaterini Argyraki, Line Katrine Harder Clemmensen, Paul Michael Petersen A. Argyraki, M. Markvart , Anne Nielsen, T. Bjarnsholt , L. Bjørndal , P. M. Petersen Effect of illumination p.value 0,029<0,05 Illumination setting Average vein identification output Standard deviation of vein identification output Average performance improvement % 1 (CCT 2600K) 17.1 2.6 Not appl. 2 (CCT 3700K) 19.2 3.5 12.3 3 (CCT 4400K) 18.2 6.4 4 (CCT4700K) 20.2 18.1 5 (CCT 4900K) 19.1 11.7 6 (CCT 5400K) 18.6 8.8 7 (CCT 5700K) A special LED lamp with high color rendering (CRI 84-95) was developed and the effect of correlated color temperature (CCT) was evaluated, in the range between 2600 K and 5700 K at an illuminance level of 40±9 lux on the ability of adult humans to identify veins.