A single-particle optical sensor, which has high sensitivity and responds to relatively concentrated suspensions, uses a relatively narrow light beam to illuminate an optical sensing zone nonuniformly. The zone is smaller than the flow channel so that the sensor responds to only a fraction of the total number of particles flowing through the channel, detecting a statistically significant number of particles of any relevant diameter. Because different particle trajectories flow through different parts of the zone illuminated at different intensities, it is necessary to deconvolute the result. Two methods of deconvolution are used: modified matrix inversion or successive subtraction. Both methods use a few basis vectors measured empirically or computed from a theoretical model, and the remaining basis vectors are derived from these few. The sensor is compensated for turbidity. Several embodiments are disclosed employing light-extinction or light-scattering detection, or both.

Sensors and methods for high-sensitivity optical particle counting and sizing

The invention encompasses analyzers and analyzer systems that include a single particle analyzer, methods of using the analyzers and analyzers systems to analyze samples, either for single particles or for multiple particles (multiplexing), methods of doing business based on the use of the analyzers or analyzer systems of the system, and electronic media for storing parameters useful in the analyzers and analyzer systems of the invention.

System and methods for sample analysis

A particle detector has a sample area of cross section no in excess of about 2 mm for containing environmental fluid, a light source on one side of the sample area for directing a collimated or nearly collimated beam of light through the sample air or water so that part of the light beam will be scattered by any particles present in the air or water while the remainder remains unscattered, and a beam diverting device on the opposite side of the sample area for diverting or blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light onto a detector. The detector produces output pulses in which each pulse has a height proportional to particle size and a pulse height discriminator obtains the size distribution of airborne particles detected in the air or water sample at a given time from the detector output. The detector may also include a device for discriminating between biological agents and inorganic particles.

Pathogen and particle detector system and method

Disclosed are methods, kits, and compositions for the highly sensitive detection of molecules. The methods, kits, and compositions are useful in determining concentrations of molecules in samples to levels of 1 femtomolar, 1 attomolar, or lower. The methods, kits, and compositions also allow the determination of concentration over a wide range, e.g., 7-log range, without need for sample dilution.

Methods and Compositions for Highly Sensitive Detection of Molecules

The invention encompasses analyzers and analyzer systems that include a single molecule analyzer, methods of using the analyzer and analyzer systems to analyze samples, either for single molecules or for molecular complexes. The single molecule uses electromagnetic radiation that is translated through the sample to detect the presence or absence of a single molecule. The single molecule analyzer provided herein is useful for diagnostics because the analyzer detects single molecules with zero carryover between samples.

Scanning analyzer for single molecule detection and methods of use

Two beams of electromagnetic radiation with symmetric radial intensity distributions are directed through space. A particle sampling volume is defined by those portions of the two beams within the field of view of one or more radiation sensitive detectors. The detectors respond to scattered radiation or fluorescence from particles passing through the beams in the sampling volume. The detector output for a single particle indicates two signal pulses corresponding to those times when the particle was in one of the beams. The speed of the particle in the plane perpendicular to the beams is determined from the transit time or width of the signal pulses, and the angle of the particle traverse in that plane determined from the time-of-flight between the signal pulses. The speed and angle thereby determine two velocity components in the perpendicular plane. Then the exact particle trajectory is specified by the angle and one point on the trajectory which is determined from relative magnitudes of the signal pulses. This allows calculation of the radiation intensity incident on the particle throughout the trajectory from known radiation beam properties. A device then responds to the signal pulses to indicate the size or other physical properities of the particle without the ambiguity present if the incident radiation intensity is unknown.

Jr. Edwin D. Hirleman

Papers

Technique for simultaneous particle size and velocity measurement