Chamber design and intensity-modulated ultraviolet-C LEDs for advanced pulsed photonic disinfection

Contaminated apparatus and surgical tools pose serious health risks. For such purpose, disinfection chambers are employed. However, these systems rely on mercury-based UV lamps which comes with various drawbacks. These limitations have driven interest in Ultraviolet-C Light Emitting Diode (UV-C LED) technology as a safer and more efficient alternative. However, existing studies have not thoroughly explored the impact of varying intensities of pulse width modulation (PWM) on disinfection efficacy.

To addess this, the present study designed and tested a LED-based disinfection chamber by employing 4-W 275 nm Surface Mount Device (SMD) LEDs against frequently isolated bacteria. By following prior approach, irradiation time was alternated at 30-s intervals and antibacterial efficacy was assessed through various parameters. Additionally, scanning electron microscopy (SEM) was performed to examine the morphological changes.

Results indicated that the reduction was significantly influenced (p<0.05) with varying PWM levels (60-100 %), achieving 2.05-log₁₀ and 1.54-log₁₀ inactivation against Escherichia coli and Staphylococcus aureus, respectively, upon exposure to 51.24 mJ/cm² under maximum exposure settings. Moreover, complete cellular damage leading to bleb protrusion and cell-leakage confirmed the disruption of bacterial DNA.

In conclusion, UV-LEDs show great potential for disinfection, with efficiency influenced by PWM and dosage.