Particle Sensor with Interferent Discrimination

A device for determining the concentration of particles in a vessel, which device comprises:

• a housing;
• a sensor in the housing and comprising a first light source, wherein a wavelength emitted by the light source is absorbed by a medium of interest, which absorption is characterized by a mean absorption path length;
• the sensor further comprising a first detector positioned to detect a signal of the first light source wavelengths scattered by particles within the medium;
• and,
• a processor configured to correlate the detected signal to the concentration of particles;
• wherein a distance between a central optical axis of the first light source and a central optical axis of the first detector at an interface between the vessel and the medium is 2-fold less than the mean absorption path length;
• and,
• wherein a distance between the optical interface with the medium and a non-biological stationary object within the emission cone of the light source, is greater than the mean absorption path length.

A method of determining the concentration in a medium of a first particle type in the presence of a second particle type, the method comprising:

• a) illuminating the medium with a first light source;
• b) detecting light from the first light source, which light has been reflected from within the medium to a detector that generates a signal;
• c) computing a first statistical measure that is related to a central value of the detector signal;
• d) computing a second statistical measure that is related to the distribution of the signal;
• and,
• e) combining the first and second statistical measures to determine the concentration of the first particle type in the medium;
• whereby said combining statistical measures reduces a background signal contribution of second particle type light reflections to the concentration determination.

A method of determining the concentration in a medium of a first particle type in the presence of a second particle type, the method comprising:

• a) illuminating the medium with a first light source;
• b) detecting light from the first light source, which light has been reflected from within the medium to a detector that generates a signal;
• c) computing a first statistical measure that is related to a central value of the detector signal;
• d) computing a second statistical measure that is related to the distribution of the signal;
• and,
• e) combining the first and second statistical measures to determine the concentration of the first particle type in the medium;
• whereby the determined concentration of the first particle type has reduced dependence on the concentration of the second particle type in the medium, compared to a determination based on a mean of the signal.

A method of determining the concentration in a medium of a first particle type in the presence of a second particle type that comprises the steps of:

• a) passing light originating from a first light source into the medium;
• b) detecting a first light signal, wherein the signal is from light originating from the first light source that was reflected from within the medium, wherein the detection bandwidth and the measurement volume allow signal fluctuations due to the second particle type to be resolved, whereas the signal due to the first particle type is substantially constant at a given concentration;
• c) separating the signal fluctuations from the constant signal to determine the concentration of the first particle type;
• whereby the concentration of the first particle type is determined with reduced error due to background reflectance signals from the second particle type in the medium.

A device for determining the concentration in a medium of a first particle type in the presence of a second particle type, which device comprises:

• a) a housing containing a sensor;
• b) a first light source in the sensor, wherein light emitted by the source is passed into the medium;
• c) a first detector in the sensor positioned to detect a signal of source light scattered by particles within the medium, wherein the detection bandwidth and the measurement volume are configured to allow signal fluctuations due to the second particle type to be resolved, whereas the signal due to the first particle type is substantially constant at a given concentration;
• d) a processor programmed to substantially separate the signal fluctuations from the constant signal and correlate the results to the concentration of the first particle type.

A device for determining the concentration of particles, which device comprises:

• a light source configured to emit a wavelength;
• a container comprising a wall transparent to the wavelength, the wavelength emitted by the light source being transmissible through the container wall and absorbed by a medium of interest, which absorption is characterized by a mean absorption path length;
• a light detector configured to detect the first wavelength of light, and positioned to detect a signal of source light scattered by particles within the medium in the container through the container wall, wherein a distance between an optical interface with the medium and the opposite side of the container, is substantially greater than the mean absorption path length;
• a rear support for the container which is located on an opposite of the container from the sensor and which support urges the container against the sensor;
• and,
• a processor programmed to correlate the detector signal to the concentration of particles in the medium.