Pulsed Purple Light Microbe Inactivation
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) used for phototherapy deliver high irradiances and radiant exposures that can effectively kill bacteria but may damage surrounding tissues and pose optical hazards, and there is a need for a method that can inactivate microorganisms at lower irradiances and exposures.
Innovation Solution
The use of pulsed purple or blue light with specific pulse parameters, dosages, and time intervals to optically excite photoactive molecules, creating oxidation reactions that destroy microorganisms without damaging surrounding tissues, including the application of pulsed light to inactivate bacteria, viruses, and fungi in skin, tissue, environments, and food.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LEDs operate in continuous wave mode to deliver high irradiances and radiant exposures, then bacteria kill rate is improved, but tissue damage and optical hazards increase
Solution Approach 1:
The patent applies periodic pulsed light irradiation instead of continuous wave irradiation. The light is delivered in discrete pulses with specific duration and interval parameters, allowing photodynamic inactivation of microorganisms during pulse periods while providing rest periods that reduce cumulative thermal and photochemical damage to surrounding tissues. This periodic action maintains effective antimicrobial activity while mitigating harmful effects on host tissues.
2Productivity
If high irradiances and radiant exposures are used to increase bacteria kill rates, then microorganism inactivation is improved, but damage to surrounding tissues through thermal or photochemical effects increases
Solution Approach 1:
The pulsed irradiation regime delivers light in periodic bursts rather than continuously. During the pulse on-time, sufficient energy is provided to activate photosensitizers and generate reactive oxygen species that kill microorganisms. During the off-time periods, thermal energy dissipates and photochemical reactions subside, preventing accumulation of damaging heat and reactive species in surrounding tissues. This temporal separation maintains therapeutic efficacy while reducing adverse effects.
Solution Approach 2:
The patent modifies the irradiation parameters by using pulsed delivery with specific pulse widths, frequencies, and duty cycles rather than continuous irradiation. These parameter changes allow optimization of the balance between delivering sufficient total energy for microbial inactivation while keeping peak irradiances and cumulative exposures below thresholds that cause significant thermal or photochemical damage to host tissues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The pulsed light system effectively inactivates microorganisms at lower irradiances and exposures, reducing the risk of tissue damage and optical hazards, while maintaining high bacterial kill rates, and can be used to sanitize environments and extend food shelf life.
Implementation Method 1
the light pulses have a peak irradiance and a pulse duration sufficient to optically excite the photoactive molecule and (b) the light pulses are separated by an off time sufficient to allow the photoactive molecule to return to a ground state creating an oxidation reaction that produces free radicals
Implementation Method 2
The target is irradiated with pulsed purple or blue light so as to destroy the RNA or DNA genomes of all or a portion of the microorganisms
Data Source
AI summary
The present invention is directed to a system and method for photoeradication of microorganisms from a target. The method includes the step of obtaining test data for a plurality of experiments each of which comprises irradiating test microorganisms with a plurality of light pulses having a wavelength that ranges from 380 nm to 500 nm. The light pulses have a plurality of pulse parameters (peak irradiance, pulse duration, and off time between adjacent light pulses) and are provided at a radiant exposure that ranges from 0.5 J/cm2 to 60 J/cm2 during each of a plurality of irradiation sessions. The test data comprises a survival rate for the test microorganisms after irradiation with the light pulses. The method also includes the step of analyzing the test data to identify the pulse parameters for the light pulses and the radiant exposure for each of the irradiation sessions that result in a desired survival rate for the test microorganisms. The method further includes the step of irradiating the microorganisms of the target with light pulses having the identified pulse parameters at the identified radiant exposure for each of the irradiation sessions so as to photoeradicate all or a portion of the microorganisms.