Leland Stanford Junior University

Xerox Corporation

Becton Dickinson and Company Limited

Richard G Sweet

Richard T Stovel

Tom Nozaki, Jr

David R Parks

Wayne A Moore

Joseph G Carleton

A droplet-deflection flow sorter images a series of droplets, analyzes the image to determine droplet spacing, and alters flow velocity to achieve a desired spacing. Cells in a suspension are forced by gas pressure into a narrow conduit to serialize them and then out a nozzle that includes a 'window' that allows cells of interest to be characterized. Droplets breaking off from the exiting jet are imaged by a video system including a strobed light source and a video camera. Droplet spacing is determined by locating the centers of gravity of the droplets. The centers of gravity are located by processing the droplet images to produce line segments corresponding to volumetric droplet slices, with the relative volumes of the slices being proportional to the squares of the line segment lengths. This approach determines droplet center positions and thus spacing more accurately than non-imaging methods, especially with aspherical droplets and droplets with satellites. The actual droplet spacing is compared to desired spacing, and the pressure regulator is adjusted accordingly. Synchronously, voltage is applied to droplets of interest. The droplets pass between a pair of deflection plates with a potential difference between them, so that charged droplets containing cells of interest are deflected and gathered while uncharged droplets not containing such cells are not deflected.

Flow sorter with video-regulated droplet spacing

An apparatus for a Nozzleless Droplet Projection System (10) is disclosed. The invention employs a novel geometry for producing a thin film of ink (26) having a constant depth traveling at a constant velocity across a tubular transducer head (16a, 16b). The head includes a smooth exterior perimetrical surface (18) that faces toward a sheet of paper (14) and a laminar flow regulator (28) that resembles a knife-edge. An array of electro-acoustic transducers (15) submerged beneath the transducer head support surface (17) generates tone bursts (20) of acoustic energy which are focused by a corresponding array of acoustic lenses (19) inscribed along the length of the transducer head (16a, 16b). A constant thickness and constant velocity fluid film (26) is generated by forcing pre-regulated, pressurized fluid (33) through a narrow slit (30) and across the smooth perimetrical surface (18) of the transducer head (16a, 16b). The dimensions of the slit (30) are defined by the space separating the laminar flow regulator (28) and the smooth exterior surface (18) of the print head. The ink film (26) is maintained at the acoustic focus of the lenses (19) to control the size of droplets of ink (12) that are ejected from the print head toward a sheet of paper (14). A pattern of droplets (12) is ejected by pulsing the appropriate electro-acoustic transducers (15) as the paper (14) is moved across the apparatus at a constant velocity. The cooperative action of the knife-edge shaped laminar flow regulator (28) and the smooth surface (18) of the print head (16a, 16b) provides a stable, fixed-depth, non-undulating film down stream from slit (30). The elastic action of a meniscus (46, 48) of fluid formed in slit (30) regulates the fluid velocity and depth along smooth exterior surface (18) during operation of the apparatus (10).

Nozzleless droplet projection system

Method and apparatus for sorting individual particles into containers, such as the wells of a microculture tray, are disclosed. The particles may comprise, for example, individual biological cells which then may be cultured, cloned, analyzed, or the like. The particles are incorporated into a flow stream which is jetted from a nozzle which is vibrated in the direction of the stream to break the jet stream into discrete drops. A particle sensor senses particles in the stream, and a signal processor in response to the particle sensor output produces an output when the sensed particle is of the type to be sorted from the stream. A pulse charger, responsive to the signal processor, is included for charging the drops as they break from the vibrating jet stream. The drops pass between charged deflection plates where they are deflected an amount related to the drop charge. For individual cell sorting, the signal processor is in normal inopertive condition to prevent sorting of drops from the drop stream. During this time all drops contained in the stream are caught by a stream catcher, and none are allowed to enter a tray well. When armed, by manual actuation of an arming switch, the circuit is conditioned to sort a single particle from the drop stream, at which time the circuit returns to normal inoperative condition. A tray support is provided for movable support of the multiwell tray along perpendicular X and Y directions, and a releasable detent releasably lock the tray support at any desired X-Y position. The tray support is provided with a target for use in initial alignment of the tray support relative to drops separated from the stream to assure entry of such drops into a tray well during subsequent operation of the cell sorter.

Method and means for sorting individual particles into containers for

Method and apparatus for semi-automatic feeding of liquid samples from a plurality of sample sources to a scanning device are disclosed. The liquid samples are picked up from a preidentified sample source and delivered to the scanning device by use of a hand-held pick-up and delivery tube. The hand-held tube is releasably coupled to the scanning device for delivery of the liquid samples to the scanning device when coupled thereto. In the disconnected condition, particle free fluid flows in a reverse direction from the scanning device for automatic flushing of the scanning device and liquid sample supply line connected thereto. Visual display means for visually indicating to the operator which sample holder the next sample is to be obtained from is provided.

Method and means for delivering liquid samples to a sample scanning

Particle analyzing method and apparatus are provided for measuring the intensity of light scattered from a particle as a function of angle. Particles such as biological cells are contained in a stream for travel along a path which includes a scatter line along which the particles pass successively. A beam of collimated monochromatic radiation is directed onto the flow path, and detector means are provided having a radiation acceptance geometry whose projection intercepts the beam along the scatter line. The projected acceptance geometry includes an aperture image located adjacent the scatter line and having a dimension in the direction of travel of the particles which is substantially less than the length of the scatter line such that the angle of scatter radiation detectable by the detector means varies according to the position of the particle along the scatter line. The output from the detector provides a measure of the scatter light intensity versus angle characteristic of the particle.

Growing community of inventors

Palo Alto, CA, United States of America

Richard G Sweet