**7. Decontamination**

One final step has been taken to reduce the risk of microorganism contamination even further. A UV-C light has been built into the incubator. The UV-C LED source itself is behind the bowl of the incubator but the UV-C light is led out through a fused silica light guide which passes along the shaft of the fan. UV-C capture from the LED was calculated to be 88%. By terminating the light guide in an arrow shape (with angles of 52 and 56 °), the emitted UV-C sweeps the incubator as the fan rotates. Normally, UV-C light reflectance from stainless steel is usually about 5% but this has been increased to about 75% by using a special ePTFE coating. Thus, the UV-C irradiation is reflected in all directions and will reach all surfaces. All clinostat motors are activate during decontamination so that all sides of the culture vessel holder will also be irradiated. The inner surface of the glass door is assumed to be totally absorbing for the UV-C. According to the specifications of the LED lamp, the UV-C light emitted will provide a dose of at least 12 mJ/cm2 everywhere in the incubator after 2 hours. This results in a log4 reduction (99.99% reduction) in viable bacteria. A log6 reduction is normally defined as sterile for medical facilities (and therefore this is classified only as a decontamination).
