Method and apparatus for positioning the point of droplet formation in the jetting fluid of an electrostatic sorting device
First Claim
1. An electrostatic particle sorting system, comprising:
- (a) flow means for establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong;
(b) particle sensing means for optically detecting said particles at least at said particle sensing point;
(c) perturbation means for perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream become a series of discrete droplets;
(d) droplet charging means for relatively charging selected ones of said droplets as they are formed at said breakpoint; and
(e) synchronization means for timing said relative charging such that said selected droplets contain at least selected particles detected by said optical detection means;
said synchronization means comprising;
(i) sheath sensing means for sensing at least the light scatter characteristic of said stream at a sheath sensing point therealong subsequent to said perturbation and for producing a surface character output signal which is proportional thereto;
(ii) surface character analysis means for producing an output signal which is at least selectively responsive to said surface character output signal; and
(iii) amplitude adjustment means responsive to said surface character analysis means for adjusting said amplitude of said perturbation means for establishing and maintaining said breakpoint at said sheath sensing point.
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Abstract
A novel method for positioning the point of droplet formation in the jetting fluid of an electrostatic sorting device is disclosed. The formation of the uniform droplets is carried out via the application of vibrational energy inparted by a transducer to a jetting laminar flow stream. Previously sensed particles contained within the core portion of the laminar stream are subsequently sorted from the stream as part of a subsequently formed droplet. The disclosed method uses the dependency of the droplet formation point on the amplitude of the wave form applied to the transducer and the modulation of this amplitude to control the droplet formation point distance. The position of the droplet formation point is detected via the use of a light source and photodetector focused on the jetting stream at the position at which the droplet formation point is to be located, and a method for automatically maintaining the breakpoint at that position is described.
131 Citations
13 Claims
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1. An electrostatic particle sorting system, comprising:
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(a) flow means for establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) particle sensing means for optically detecting said particles at least at said particle sensing point; (c) perturbation means for perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream become a series of discrete droplets; (d) droplet charging means for relatively charging selected ones of said droplets as they are formed at said breakpoint; and (e) synchronization means for timing said relative charging such that said selected droplets contain at least selected particles detected by said optical detection means;
said synchronization means comprising;(i) sheath sensing means for sensing at least the light scatter characteristic of said stream at a sheath sensing point therealong subsequent to said perturbation and for producing a surface character output signal which is proportional thereto; (ii) surface character analysis means for producing an output signal which is at least selectively responsive to said surface character output signal; and (iii) amplitude adjustment means responsive to said surface character analysis means for adjusting said amplitude of said perturbation means for establishing and maintaining said breakpoint at said sheath sensing point. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of electrostatically sorting particles comprising:
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(a) establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) optically detecting said particles at least at said particle sensing point; (c) perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream becomes a series of discrete droplets; (d) relatively charging selected ones of said droplets as they are formed at said breakpoint; and (e) synchronizing said relative charging such that said selected droplets contain at least selected particles detected in said optical detection step;
said synchronizing step comprising the steps of;(i) sensing at least the light scatter characteristics of said stream at a sheath sensing point therealong downstream from said perturbing for producing a surface character output signal which is proportional thereto; (ii) analyzing said surface character output signal to produce an output signal which is at least selectively responsive to said surface character output signal; and (iii) adjusting said preselected amplitude in said perturbing step in response to said selectively responsive output signal to establish and maintain said breakpoint at said sheath sensing point. - View Dependent Claims (8, 9, 10, 11)
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12. An electrostatic particle sorting system, comprising:
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(a) flow means for establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) particle sensing means for detecting said particles at least at said particle sensing point; (c) perturbation means for perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream become a series of discrete droplets; (d) droplet charging means for relatively charging selected ones of said droplets as they are formed at said breakpoint; and (e) synchronization means for timing said relative charging such that said selected droplets contain at least selected particles detected by said detection means;
said synchronization means comprising;(i) sheath sensing means for sensing at least the light scatter characteristic of said stream at a sheath sensing point therealong subsequent to said perturbation and for producing a surface character output signal which is proportional thereto; (ii) surface character analysis means for producing an output signal which is at least selectively responsive to said surface character output signal; and (iii) amplitude adjustment means responsive to said surface character analysis means for adjusting said amplitude of said perturbation means for establishing and maintaing said breakpoint at said sheath sensing point.
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13. A method of electrostatically sorting particles comprising:
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(a) establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) detecting said particles at least at said particle sensing point; (c) perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream becomes a series of discrete droplets; (d) relatively charging selected ones of said droplets as they are formed at said breakpoint; and (e) synchronizing said relative charging such that said selected droplets contain at least selected particles detected in said detection step;
said synchronizing step comprising the steps of;(i) sensing at least the light scatter characteristics of said stream at a sheath sensing point therealong downstream from said perturbing for producing a surface character output signal which is proportional thereto; (ii) analyzing said surface character output signal to produce an output signal which is at least selectively responsive to said surface character output signal; and (iii) adjusting said preselected amplitude in said perturbing step in response to said selectively responsive output signal to establish and maintain said breakpoint at said sheath sensing point.
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Specification