Ultraviolet rays are light that can destroy DNA and proteins in the living body, and can kill viruses and bacteria simply by irradiating them.On the other hand, even for humans, there is a risk of atopic dermatitis and skin cancer when exposed to ultraviolet rays exceeding the values ​​regulated by law, so a safe and simple sterilization technology that replaces ultraviolet sterilization is required. ..

　Visible light is not harmful to the human body as represented by sunlight, but it has no bactericidal effect simply by irradiating it.Therefore, this group has independently developed a technology to sterilize by generating visible light in the wavelength range that bacteria and viruses efficiently absorb and irradiating it with high brightness instantaneously (about nanoseconds).It applies the principle of "resonance excitation" that enables efficient light heating by irradiating high-intensity visible light generated by a wavelength-variable pulse laser according to the light absorption spectrum of bacteria and viruses. ..Human cells are much larger than bacteria and viruses, so they cause little temperature rise, but bacteria and viruses are easily sterilized at high temperatures.

　When an experiment was conducted using this device to make gold particles look like bacteria and viruses, the temperature of the solution rose only about 2 degrees, whereas the gold particles that absorbed the pulsed laser light were instantaneous. It reached a high temperature of 1000 degrees or more.In addition, experiments using E. coli demonstrated that 99.99% of E. coli could be sterilized.

　This visible pulse light sterilization technology is a safe and new light disinfection technology that does not use ultraviolet rays that are dangerous to the human body.Furthermore, it is said that pulse flash light can be easily constructed by semiconductor light emitting device (LED) manufacturing technology, and it is expected that it will be expanded and spread to lighting equipment equipped with a sterilizing function in the future.

Paper information:[Scientific Reports] Mechanism of transient photothermal inactivation of bacteria using a wavelength-tunable nanosecond pulsed laser