Determination of turbidity using elastically and inelastically scattered light
Inventors
Chaiken, Joseph • Goodisman, Jerry
Assignees
Publication Number
US-11415511-B2
Publication Date
2022-08-16
Expiration Date
2030-09-23
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Abstract
The invention provides a method of determining turbidity and concentration simultaneously a sample by irradiating the sample with a single incident wavelength and simultaneously measuring wavelength shifted (IE) and unshifted (EE) light emitted. A relative volume of light emitted from two phases may be determined, wherein the two phases comprise a first Rayleigh and Mie scattering and fluorescent phase associated with suspended particles, and a second, non-scattering but fluorescent phase associated with suspending solution. Volumes of the phases and/or concentrations of specific fluorophores or Raman active species are calculated from the volume of light emitted by the first phase relative to the total volume of light emitted from the first and second phases.
Core Innovation
The invention provides a non-invasive method and system for determining the turbidity and concentration of a sample by irradiating it with a single incident wavelength and simultaneously measuring both the wavelength shifted (inelastically scattered, IE) and unshifted (elastically scattered, EE) light emitted from the sample. The approach leverages the distinct behaviors of light as it interacts with different phases within the sample—specifically, a first phase characterized by Rayleigh and Mie scattering and fluorescence associated with suspended particles, and a second, non-scattering yet fluorescent phase related to the suspending solution.
The algorithm uses the relative volumes of light emitted from these two phases to calculate the phase volume fractions or concentrations of specific fluorophores or Raman active species. This is accomplished by mathematical inversion of equations relating EE and IE intensities to the volume fractions, allowing simultaneous determination of both turbidity (suspended particles) and concentration (fluorophores or Raman species). The unique design permits the acquisition of independent information from the two forms of scattered light, which are linked to physical particle presence and chemical characteristics, respectively.
The problem addressed is the lack of a non-invasive method for accurately measuring the amount of suspended material—such as in algal or bacterial cultures—in samples without needing to remove aliquots, which could risk contamination. The invention specifically provides a solution by enabling simultaneous, contamination-free measurement of turbidity and concentration directly in vitro, improving accuracy and utility for monitoring biological processes.
Claims Coverage
The patent contains one independent claim covering a system for determining turbidity based on simultaneous measurement of elastically and inelastically scattered light.
Simultaneous collection and distinction of elastically and inelastically scattered light
A laser directs light of a predetermined wavelength into a sample containing a fluid and suspended particles. A detector is aligned to simultaneously collect emitted light at the incident (unshifted) wavelength and at a shifted (inelastic) wavelength. The detector distinguishes between the two emission types and determines turbidity based on the relative intensity of these signals.
Relating emitted light intensities to phase volumes in the sample
The system is configured so that the collected unshifted (predetermined wavelength) light represents the volume of the fluid phase, and the collected shifted light represents the volume of the suspended particle phase. The detector determines turbidity by evaluating the ratio between these intensities.
The inventive features center on a system that uses a laser and detector to non-invasively measure turbidity by collecting and distinguishing elastically and inelastically scattered light and directly relating these intensities to the fluid and particle volumes in the sample.
Stated Advantages
The invention allows non-invasive measurement of suspended material in a sample, reducing the risk of contamination.
Simultaneous determination of both turbidity and concentration is achieved using a single measurement event, improving efficiency.
Provides more accurate methods of measuring turbidity in biological samples by utilizing both inelastic and elastic scattering intensities.
Enables real-time assessment of biological processes, such as algae or bacterial growth, without the need for sample removal.
Documented Applications
Measurement of algae growth in biofuel production solutions prior to processing.
Determination of bacterial viability during the growth of a bacterial culture.
Fluorescence-based immunoassays.
Nephelometry and turbidometric assays for biofluids.
Quantitative protein analysis.
Bioreactor design and process control.
Stem cell culturing and production.
Cell viability testing.
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