Microbial particle counting system and microbial particle counting method
Inventors
Assignees
Publication Number
US-11119027-B2
Publication Date
2021-09-14
Expiration Date
2037-11-07
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Abstract
A microbial particle is accurately counted in distinction from a non-microbial particle. A preceding-stage irradiation section 2 irradiates a sample as fluid with ultraviolet light at a preceding stage of a microbial particle counter 1. The ultraviolet light is ultraviolet light having a deep ultraviolet region, the ultraviolet light increasing the fluorescence intensity of a first autofluorescence substance in the microbial particle. The microbial particle counter 1 measures light intensity in a first wavelength range including the fluorescence wavelength of the first autofluorescence substance. In addition, the microbial particle counter 1 measures light intensity in a specific second wavelength range. Further, the microbial particle counter 1 counts the microbial particle in distinction from a non-microbial particle in the fluid based on the measured light intensity in the first wavelength range and the measured light intensity in the specific second wavelength range.
Core Innovation
The invention provides a microbial particle counting system and method that accurately counts microbial particles distinct from non-microbial particles by utilizing ultraviolet light irradiation in a deep ultraviolet region to increase fluorescence intensity of specific autofluorescence substances within microbial particles. The system includes a microbial particle counter that irradiates the fluid sample with excitation light to detect autofluorescence and count microbial particles, and a preceding-stage irradiation section that irradiates the sample with deep ultraviolet light prior to measurement.
The ultraviolet light increases the fluorescence intensity of a first autofluorescence substance in the microbial particle, such as components of the flavin or folate groups. The microbial particle counter measures light intensities in a first wavelength range including the fluorescence wavelength of the first autofluorescence substance and in a second specific wavelength range, and counts microbial particles based on a comparison of these measured intensities to distinguish them from non-microbial particles.
The problem addressed by the invention is that microbial particle fluorescence is weak and sometimes buried in background noise, which prevents accurate detection and differentiation from non-microbial particles. Prior methods either could not detect individual microbial particles or failed to distinguish microbial particles from non-microbial particles emitting fluorescence due to excitation. This invention solves the issue by employing deep ultraviolet light in a preceding irradiation step to enhance autofluorescence intensity and using dual wavelength range measurements to accurately discriminate microbial particles.
Claims Coverage
The patent includes several independent claims focusing on a microbial particle counting system and method with a preceding ultraviolet irradiation step and dual or multiple wavelength range fluorescence measurement to distinguish microbial particles from non-microbial particles.
Preceding-stage deep ultraviolet irradiation to enhance microbial autofluorescence
The system includes a preceding-stage irradiation section that irradiates a fluid sample with ultraviolet light in a deep ultraviolet region, which increases fluorescence intensity of a specific autofluorescence substance in microbial particles.
Dual wavelength range measurement for microbial particle counting
The microbial particle counter measures light intensity in a first wavelength range including fluorescence from the specific autofluorescence substance and in a second wavelength range, and counts microbial particles by comparing these intensities to differentiate them from non-microbial particles.
Threshold-based counting criteria
The microbial particle counter counts microbial particles only when the measured intensities in both first and second wavelength ranges exceed predetermined thresholds set according to intensity increments caused by the ultraviolet irradiation.
Specific wavelength range selection excluding peak autofluorescence and Raman peaks
The second wavelength range is predetermined between the excitation wavelength and the first wavelength range and excludes fluorescence peak wavelengths increased by ultraviolet light and Raman scattered light peaks, allowing accurate distinction.
Counting based on intensity difference within a predetermined range for multiple autofluorescence substances
Where the second wavelength range corresponds to fluorescence of a different autofluorescence substance, the microbial particle counter counts the particle when the difference between intensity in the first and second wavelength range is within a predetermined range.
Measurement with additional wavelength ranges and gradient-based counting
The system can measure light intensity in at least one additional wavelength range and determine counting of microbial particles based on gradients of intensities across the measured wavelength ranges.
Microbial particle counting method applying preceding deep ultraviolet irradiation and dual wavelength measurement
The method involves irradiating the sample with deep ultraviolet light prior to microbial particle counting, measuring light intensities in dual wavelength ranges, and counting microbial particles based on the relative intensities in those ranges according to the specified thresholds.
The claims collectively cover a system and method using preceding deep ultraviolet irradiation to enhance microbial autofluorescence, measurement of multiple wavelength ranges excluding confounding peaks, threshold and comparative intensity criteria, and the use of additional wavelength ranges and gradients to accurately count microbial particles distinct from non-microbial particles.
Stated Advantages
The microbial particle is accurately counted in distinction from non-microbial particles due to increased fluorescence intensity from deep ultraviolet irradiation and comparative measurement in specific wavelength ranges.
Documented Applications
The invention is applicable to counting microbial particles in fluid samples, including liquids such as water and gases such as air.
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