Method of and apparatus for detecting change in the breakoff point in a droplet generation system

• US 4,691,829 A
• Filed: 12/06/1984
• Issued: 09/08/1987
• Est. Priority Date: 11/03/1980
• Status: Expired due to Fees

• Current Assignee: Coulter Corporation (Danaher Corporation)
• Original Assignee: Coulter Corporation (Danaher Corporation)
• Inventors: Auer, Robert E.
• Primary Examiner(s): Reeves, Robert B.
• Assistant Examiner(s): Wacyra, Edward M.
• Application Number:
  US06/678,613
• Time in Patent Office: 1,006 Days
• Field of Search: 209/3.1-3.3, 209/44.1, 209/44.2, 209/546, 209/548, 209/549, 209/571, 209/579, 209/906, 209/127 R, 250/222.2, 356/39, 356/72, 356/73, 356/335, 356/338, 361/226, 364/413, 346/75
• US Class Current: 209/3.1
• CPC Class Codes: G01N 15/1404 Handling flow, e.g. hydrodynamic focusing
• CPC Class Codes: G01N 2015/1406 Control of droplet point
• CPC Class Codes: Y10S 209/906 Pneumatic or liquid stream feeding item

Abstract

A particle separator for sorting particles suspended in a liquid according to certain characteristics, including a method of and apparatus for detecting a change in the droplet breakoff point of a liquid jet stream which is subjected to vibrations. The vibrations produce amplitude undulations on the surface of the jet stream. The amplitude of the undulations is monitored or interrogated at a fixed point on the jet stream prior to the breakoff point. A change in amplitude of the undulations at that fixed point produces a signal voltage at a masked sense diode the value of which is proportional to the amplitude change. This signal voltage may be used (1) to alert the operator that a change has occurred in the point at which the jet stream is breaking up into droplets, (2) to automatically control the intensity of the vibrations for restoring the amplitude of undulation at that fixed point to its original state, or (3) to automatically disable the sorting portion of the apparatus. Any one or any combination of the foregoing three happenings can be utilized.

Claims

1. In an apparatus for analyzing and sorting particles suspended in a liquid, said apparatus including first means for producing a jet stream from said liquid suspension, second means for vibrating said jet stream to produce undulations on the surface of said stream and subsequent breakup of said stream into droplets for collection downstream, said stream having a breakpoint region, the improvement comprising:

radiation means for impinging a beam of radiation upon an uninterrupted portion of said jet stream during its analyzing and/or sorting mode at a fixed location thereon prior to the breakpoint region,

sensing means, coupled to said second means, responsive to radiation from said radiation means which is scattered by said stream, for providing an output to said second means which is proportional to the amplitude of undulation at said location, and

wherein said second means is positioned above said radiation means.

2. In an apparatus for analyzing and sorting particles suspended in a liquid, said apparatus including first means for producing a jet stream from said liquid suspension, second means for controlling the position of the breakoff point, including vibrating means for vibrating said jet stream to produce undulations on the surface of said stream and subsequent breakup of said stream into droplets for collection downstream, said stream having a breakpoint region, the improvement comprising:

radiation means for providing a beam of radiation to interrogate a portion of said jet stream at a location thereon prior to the breakpoint region by impinging said beam thereon, and

sensing means, coupled to said second means, responsive to radiation from said radiation means which interrogates said portion of said stream at said location, as a result of radiation scattered by said stream for providing an output which is a function of the amplitude of undulation at said location on said portion of said jet stream.

3. In an apparatus for analyzing and sorting particles suspended in a liquid, said apparatus including first means for producing a jet stream from said liquid suspension, second means for controlling the position of the breakoff point including vibrating means for vibrating said jet stream to produce undulations on the surface of said stream and subsequent breakup of said stream into droplets at a breakoff point for collecting downstream, said stream having a breakpoint region, the improvement comprising:

radiation means positioned below said vibrating means for impinging a beam of radiation upon said jet stream prior to said breakpoint region upon an uninterrupted portion thereof causing said jet stream to thereby scatter said radiation impinging thereon, and

sensing means, coupled to said second means further including diode detection means having a masked and an unmasked area, said unmasked area being responsive to radiation impinging thereon scattered by said jet stream, for providing an output to said second means which is a function of the magnitude of the sensed scattered radiation and is proportional to the amplitude of undulation of said jet stream.

4. In an apparatus for analyzing and sorting particles suspended in a liquid, said apparatus including first means for producing a jet stream from said liquid suspension, second means for controlling the position of the breakoff point including vibrating means for vibrating said jet stream to produce undulations on the surface of said stream and subsequent breakup of said stream into droplets at a breakoff point for collecting downstream, said stream having a breakpoint region, the improvement comprising:

radiation means prior to said breakpoint region and below said vibrating means for impinging a beam of radiation upon an uninterrupted portion of said jet stream causing said jet stream to thereby scatter said radiation impinging thereon, and

sensing means, coupled to said second means including diode detection means comprising a sensing area having a masked and an unmasked portion, said unmasked portion varying in extent in a predictable and monotonic manner and being responsive to the sensed radiation impinging thereon scattered by said jet stream, for providing an output to said second means which is a function of the magnitude of the sensed scattered radiation and is proportional to the amplitude of undulation at said portion of said jet stream.

5. In an apparatus for analyzing and sorting particles suspended in a liquid, said apparatus including first means for producing a jet stream from said liquid suspension, second means for controlling the position of the breakoff point including vibrating means for vibrating said jet stream to produce undulations on the surface of said stream and subsequent breakup of said stream into droplets at a breakoff point for collecting downstream, said stream having a breakpoint region, the improvement comprising:

radiation means prior to said breakpoint region and below said vibrating means for impinging a beam of radiation upon an uninterrupted portion of said jet stream causing said jet stream to thereby scatter said radiation impinging thereon, and

sensing means, coupled to said second means including diode detection means comprising an isosceles triangular-shaped sensing area provided with a masked and an unmasked portion, said unmasked portion being responsive to the sensed radiation impinging thereon scattered by said jet stream, for providing an output to said second means which is a function of the magnitude of the sensed scattered radiation and is proportional to the amplitude of undulation at said portion of said jet stream.