Microbial particle measuring apparatus and microbial particle measuring method
Inventors
Assignees
Publication Number
US-11474017-B2
Publication Date
2022-10-18
Expiration Date
2040-08-26
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Abstract
A microbial particle measuring apparatus includes: a light emitter configured to irradiate a fluid with light of a predetermined wavelength over a predetermined measurement time; a fluorescence receiver configured to selectively receive fluorescence emitted from particles contained in the fluid and output a signal having a magnitude corresponding to intensity of the fluorescence; a signal acquisition unit configured to obtain the signal output from the fluorescence receiver at regular intervals over the measurement time; and a determiner configured to calculate a slope of waveform of the signal obtained by the signal acquisition unit, and determine a concentration of microbial particles contained in the fluid using an attenuation amount of fluorescence intensity generated in a time period in which the slope in the measurement time is smaller than a predetermined value as an amount of attenuation derived from the microbial particles.
Core Innovation
The invention provides a microbial particle measuring apparatus and method for accurately measuring the concentration and number of microbial particles contained in a fluid by irradiating the fluid with light of a predetermined wavelength over a predetermined measurement time and selectively receiving fluorescence emitted from particles in the fluid. The apparatus obtains a signal corresponding to fluorescence intensity at regular intervals, calculates the slope of the signal waveform, and determines microbial particle concentration using the amount of fluorescence intensity attenuation during a time period when the slope is smaller than a predetermined value, interpreting this attenuation as derived from microbial particles.
The problem addressed is that in conventional methods where blue light continuously irradiates the fluid until fluorescence nearly fades, fluorescence attenuation caused by both microbial particles and non-microbial particles, such as dust, occurs, making it difficult to isolate microbial particle concentration due to interference from non-microbial fluorescence. Thus, existing techniques cannot accurately measure microbial particle concentration without this interference.
The disclosed approach exploits the different attenuation rates of fluorescence intensity depending on the fluorescent substances contained in the particles, specifically using tryptophan and tyrosine in microbial particles as indices. By identifying the time period when the slope of the fluorescence intensity signal is below a threshold and attributing fluorescence attenuation in that period to microbial particles, the technique accurately determines microbial particle concentration while minimizing effects from non-microbial substances.
Claims Coverage
The patent contains two independent claims describing two main inventive features related to microbial particle measurement apparatuses and methods.
Determining microbial particle concentration from fluorescence intensity attenuation slope
An apparatus comprising a light emitter irradiating fluid with a predetermined wavelength light over a measurement time, a fluorescence receiver selectively receiving fluorescence emitted by particles, a signal acquisition unit obtaining signal at regular intervals, and a determiner calculating a slope of the waveform of the obtained signal and determining microbial particle concentration using the fluorescence intensity attenuation during periods where the slope is smaller than a predetermined value as attenuation derived from microbial particles.
Counting microbial particles based on slope of fluorescence signal waveform
An apparatus comprising a light emitter, a fluorescence receiver selectively receiving fluorescence from particles in fluid and outputting a signal, a signal acquisition unit obtaining the signal, and a counter calculating a slope of the waveform and counting particles as microbial particles when there exists a time period where the slope is below a predetermined value or when the slope itself is below the predetermined value.
The claims cover methods and apparatuses for measuring microbial particle concentration or counting microbial particles by analyzing the slope of fluorescence intensity signals obtained from irradiated particles, attributing fluorescence attenuation characteristics to microbial particles distinguished from non-microbial particles.
Stated Advantages
Improved accuracy in determining microbial particle concentration by isolating fluorescence attenuation derived specifically from tryptophan and tyrosine, reducing influence from non-microbial particles.
Capability to determine microbial particle presence or absence after sterilization treatments by detecting changes or absence of fluorescence attenuation periods.
Manufacturing cost reduction and device downsizing by performing excitation and photolysis with a single light emitter.
Enhanced measurement versatility by presetting a continuous irradiation time for complete photolysis applicable across different sample fluids.
By combining with turbidimeters, the apparatus can measure both microbial and overall particle concentrations.
In the particle counting embodiment, counting microbial particles individually enables accurate quantification even during fluid flow, suppressing non-microbial particle influence.
Use of LEDs as light emitters lowers manufacturing cost compared to expensive semiconductor laser diodes in typical apparatuses.
Documented Applications
Measurement of microbial particle concentration and number in gases or liquids by analyzing fluorescence attenuation induced by deep ultraviolet light irradiation.
Monitoring effectiveness of sterilization treatments on microbial particle viability by comparing measurements before and after treatment.
Real-time detection of microbial particles in factory equipment sample fluids or other environments where particle concentration monitoring is critical.
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