US-20260126369-A1 - SUSPENDED PARTICLE DETECTION AND ANALYSIS

US20260126369A1US 20260126369 A1US20260126369 A1US 20260126369A1US-20260126369-A1

Abstract

A technique for suspended particle detection which includes irradiating at least one particle with a light source of a certain wavelength and capturing image data relating to the at least one particle with an image sensor or a camera. The technique further includes obtaining a frame of grayscale image data comprising luminance values of image data captured by the image sensor or camera. The technique also includes analyzing the image data in the frame to identify at least one particle captured in the frame. Analyzing the image data in the frame includes identifying pixels having luminance values that satisfy a threshold, determining particle contours of the at least one particle based, on the identified pixels, and generating at least one of quantitative or qualitative information for the at least one particle based, at least partially on the analyzing of the image data.

Inventors

Yan Ye
David Y.H. Pui

Assignees

REGENTS OF THE UNIVERSITY OF MINNESOTA

Dates

Publication Date: 20260507
Application Date: 20231004

Claims (20)

1 . A method of suspended particle detection comprising: irradiating at least one particle with a light source of a certain wavelength; capturing image data relating to the at least one particle with an image sensor or a camera; obtaining a frame of grayscale image data comprising luminance values of image data captured by the image sensor or camera; analyzing the image data in the frame to identify at least one particle captured in the frame, wherein analyzing the image data comprises: identifying pixels having luminance values that satisfy a threshold; and determining particle contours of the at least one particle based on the identified pixels; and generating at least one of quantitative or qualitative information for the at least one particle based at least partially on the analyzing of the image data.
2 . The method of claim 1 , wherein the light source is an external light source, wherein the light source comprises a laser or LED, and wherein the light source generates a beam of light with a wavelength below 450 nanometers (nm), such as from about 250 nm to about 350 nm.
3 . The method of claim 1 , wherein the captured image data comprises image data of at least one particle induced or enhanced by the light source.
4 . The method of claim 1 , wherein the image sensor or camera comprises a color image sensor or camera, such as a color video camera.
5 . The method of any of claim 1 , wherein the image data includes a red image data matrix, a green image data matrix, and a blue image data matrix, and wherein obtaining grayscale image data comprises at least one of summing or averaging each of the red image data matrix, the green image data matrix, and the blue image data matrix to form an overall image data matrix.
6 . The method of any of claim 1 , wherein identifying pixels having luminance values that satisfy the threshold comprises: determining local thresholds within respective subsets of pixels; comparing luminance values of pixels within each respective subsets of pixels to respective local threshold for that subset of pixels; and sweeping through the subsets to pixels to identify the pixels based on the comparison, and wherein determining particle contours comprises grouping the identified pixels of each of the respective subsets of pixels together as an island of particle contours.
7 . The method of claim 6 , wherein determining the local thresholds comprises averaging pixel values of the image data within the respective subsets of pixels.
8 . The method of claim 6 , further comprising identifying adjacent islands of particle contours as belonging to the same particle, wherein determining the particle contours comprises determining particle contours by fitting the data in the subsets of pixels using a fitting function.
9 . The method of claim 8 , wherein the fitting function is a Gaussian function.
10 . The method of claim 1 , wherein identifying pixels having luminance values that satisfy the threshold comprises: determining the threshold within the image data; comparing luminance values of pixels to the threshold; and identifying the pixels based on the comparison, and wherein determining particle contours comprises grouping the identified pixels together as an island of particle contours.
11 . The method of claim 10 , wherein determining the local thresholds comprises averaging pixel values of the image data within the respective subsets of pixels.
12 . The method of claims 1 , further comprising: applying a gain adjustment to the luminance values to determine adjusted luminance values for one or more pixels, wherein identifying pixels that satisfy the threshold comprises identifying pixels that satisfy the threshold based on the adjusted luminance values.
13 . The method of claim 1 , wherein the identified pixels comprise a first pixel and a second pixel that are separated by a distance, wherein determining particle contours comprises: assigning one or more pixels, within the distance, proximate to the first pixel and second pixel approximately the same luminance value as nearest pixel within identified pixels to create a broadened cluster of pixels that include the first pixel and the second pixel; and determining the particle contours based on the cluster of pixels.
14 . The method of claim 1 , wherein generating at least one of quantitative or qualitative information includes generating quantitative information comprising at least one of a particle count or a particle concentration.
15 . The method of claim 1 , wherein generating at least one of quantitative or qualitative information includes generating qualitative information comprising images of individual particles, sizes of the captured particles represented by the image data, and colors or dominant wavelengths of induced or enhanced light emitting from the captured particles.
16 . A system comprising: at least one light source of a certain wavelength configured to irradiate at least one particle; at least one image sensor or camera configured to capture image relating to the at least one particle; and one or more processors configured to: obtain a frame of grayscale image data comprising luminance values of image data captured by the image sensor or camera; analyze the image data in the frame to identify at least one particle captured in the frame, wherein to analyze the image data, the one or more processors are configured to: identify pixels having luminance values that satisfy a threshold; and determine particle contours of the at least one particle based on the identified pixels; and generate at least one of quantitative or qualitative information for the at least one particle based at least partially on the analyzing of the image data.
17 . A system comprising: at least one light source configured to irradiate particles for induced or enhanced light from particles; at least one image sensor or camera configured to capture image data of the particles in a detection chamber; and a particle analysis system, online or offline, to analyze the image and identify the particles captured in the image data, wherein the particle analysis system is configured to generate quantitative information such as particle count or particle concentration, or qualitative information such as individual particle image, size, and color or dominant light wavelength.
18 . The system of claim 17 , further comprising an image sensor lens system configured to focus the image sensor within a beam of the light source.
19 . The system of claim 17 , further comprising a light source lens system configured to focus or collimate a beam of light generated by the light source.
20 . The system of claim 17 , wherein the light source generates a beam comprising light rays of a known wavelength; wherein the known wavelength is less than about 450 nm, such as from about 250 nm to about 350 nm.

Description

This application is related to U.S. Provisional Application No. 63/413,962, filed Oct. 6, 2022; U.S. Provisional Application No. 63/418,882, filed Oct. 24, 2022; and U.S. Provisional Application No. 63/487,096, filed Feb. 27, 2023, the entire contents of each is incorporated by reference herein. BACKGROUND Detection of suspended particles, such as airborne particles, may be important due to the impact of suspended particles on a range of issues, from air pollution to disease transmission. Suspended particles may cause different adverse effects due to their relatively high specific surface area. Airborne nanoparticles can easily spread over a large area for extended periods and can easily enter and transfer within organisms and interact with cells and subcellular components. Detection of suspended particles may be an important step in treating fluids which contain suspended particles, evaluating systems or equipment designed to remove suspended particles. SUMMARY In general, the disclosure is directed to systems and techniques for detecting and analyzing particles suspended within a fluid, such as air. As described in more detail, the disclosed systems and techniques may use image processing to detect, analyze, quantify, and/or categorize suspended particles in air or another fluid. Furthermore, the disclosed detection and image processing techniques may be suitable to detect particles sized below about 100 nanometers, such as below about 50 nanometers, which may be beyond the capability of other particle detection techniques. The disclosed systems and techniques may be used to categorize target particle types, such as bioaerosols including bacteria, viruses, and the like. The disclosed system may be configured to detect images generated by elastic scattered light and the induced fluorescence from the particles. The system may include processing circuitry configured to store image data from one or more image sensors in a detection video. The captured images of induced fluorescence in the detection video may be converted to quantitative information about one or more particles. The quantitative data may include one or more of a particle count, particle concentration, image size distribution, or wavelength distribution of induced fluorescence. In some examples, the disclosure is directed to a technique for suspended particle detection and analysis. The technique includes irradiating at least one particle with a light source of a certain wavelength, and capturing image data relating to the at least one particle with an image sensor or a camera. The technique further includes obtaining a frame of grayscale image data comprising luminance values of image data captured by the image sensor or camera and analyzing the image data in the frame to identify at least one particle captured in the frame. Analyzing the image data includes identifying pixels having luminance values that satisfy a threshold, determining particle contours of the at least one particle based on the identified pixels, and generating at least one of quantitative or qualitative information for the at least one particle based at least partially on the analyzing of the image data. In some examples, the disclosure is directed to a system which includes at least one light source of a certain wavelength configured to irradiate at least one particle. The system also includes at least one image sensor or camera configured to capture image relating to the at least one particle. The system includes one or more processors configured to obtain a frame of grayscale image data comprising luminance values of image data captured by the image sensor or camera and analyze the image data in the frame to identify at least one particle captured in the frame. To analyze the image data, the one or more processors are configured to identify pixels having luminance values that satisfy a threshold, determine particle contours of the at least one particle based on the identified pixels, and generate at least one of quantitative or qualitative information for the at least one particle based at least partially on the analyzing of the image data. In some examples, the disclosure is directed to a system which includes at least one light source configured to irradiate particles for induced or enhanced light from particles, at least one image sensor or camera configured to capture image data of the particles in a detection chamber; and a particle analysis system, online or offline, to analyze the image data captured by the image data and identify the particles captured in the image data. The particle analysis system is configured to generate quantitative information such as particle count or particle concentration, or qualitative information such as individual particle image, size, and color or dominant light wavelength. The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent