The number of hospital acquired infection (HAI) relating to multidrug-resistant microorganisms has been rising throughout the past years. Contact with contaminated surfaces is one of the major transmission routes. Despite the fact that conventional chemical disinfectants can help prevent such transmission, they are only effective when applied properly and frequently. Moreover, microbial tolerance and surface corrosion are the major concerns of using chemical disinfectants. There is a demand for finding an alternative approach to disinfect surfaces. In this research, we aim at developing a novel light-based device that is safe for surface disinfection and optimizing its deployment. UVC (280nm), 405nm and 470nm were chosen and were assessed on their bactericidal efficacy by bacte...[ Read more ]

The number of hospital acquired infection (HAI) relating to multidrug-resistant microorganisms has been rising throughout the past years. Contact with contaminated surfaces is one of the major transmission routes. Despite the fact that conventional chemical disinfectants can help prevent such transmission, they are only effective when applied properly and frequently. Moreover, microbial tolerance and surface corrosion are the major concerns of using chemical disinfectants. There is a demand for finding an alternative approach to disinfect surfaces. In this research, we aim at developing a novel light-based device that is safe for surface disinfection and optimizing its deployment. UVC (280nm), 405nm and 470nm were chosen and were assessed on their bactericidal efficacy by bactericidal tests. Comparison between continuous and pulsed lights as well as studies of parametric factors and interaction among lightings with different wavelengths were carried out for optimization of the system. The results demonstrated the bactericidal efficacy of the chosen lightings and suggested that pulsed light at 1 Hz was a more efficient choice than continuous light. As well, synchronous light was found to reduce the bactericidal effect of mix lightings while asynchronous pre-exposure of 405nm to UVC (280nm) and alternative exposure of 470nm with 280nm lighting could enhance the bactericidal performance compared to UVC light. The evaluation of the combined lightings also showed its higher bactericidal effect when compared to UVC. Based on the results, a light disinfection system was fabricated and its bactericidal performance, material compatibility and biosafety were assessed. The system was able to achieve high bactericidal rate and at the same time did not cause high risk of material damage and safety issue.