Method for detecting and controlling flow rates of the droplet forming stream of an electrostatic particle sorting apparatus
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) optical detection 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 becomes 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 of said sheath stream portion 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 sheath sensing means;
(iii) flow rate adjustment means responsive to said surface character analysis means for establishing and maintaining a preselected flow rate of said stream.
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Abstract
A novel method is disclosed for detecting and controlling the flow rate of a perturbed, droplet-forming stream in an electrostatic particle sorting apparatus. Detection apparatus is located at two points along the stream, at a first particle sensing point for sensing the presence of particles within a core portion of the stream, and at a second downstream point, preferably the stream breakpoint, for sensing light scatter and extinction characteristics which are proportional to the surface characteristics of the sheath portion of the stream. Changes in phase shift, pulse width, duty cycle, pulse area, or breakpoint location are detected by analyzing these sheath surface-related characteristics. An error signal is produced in response to such changes which drives an electromechanical fluid flow regulator to increase or decrease the fluid flow rate in a direction which tends to minimize the error signal. The flow rate is thus maintained at a reference flow rate setting.
132 Citations
43 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) optical detection 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 becomes 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 of said sheath stream portion 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 sheath sensing means; (iii) flow rate adjustment means responsive to said surface character analysis means for establishing and maintaining a preselected flow rate of said stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of electrostatically sorting particles comprising:
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(a) establishing a flow of a continuous particle containing stream having 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 said 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 by said optical detection step;
said synchronizing step comprising the steps of;(i) sensing at least the light scatter characteristics of said sheath stream portion at a sheath sensing point therealong subsequent to the point of said perturbation for producing a surface character output signal which is proportional thereto; (ii) analyzing said surface character output signal to produce an analyzed output signal which is at least selectively responsive to said sheath sensing means; and (iii) adjusting the flow of at least a portion of said continuous particle containing stream at least in response to said analyzed output signal. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. 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) detection 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 becomes 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 of said sheath stream portion 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 sheath sensing means; (iii) flow rate adjustment means responsive to said surface character analysis means for establishing and maintaining a preselected flow rate of said stream.
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43. A method of electrostatically sorting particles comprising:
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(a) establishing a flow of a continuous particle containing stream having 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 said 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 by said detection step;
said synchronizing step comprising the steps of;(i) sensing at least the light scatter characteristics of said sheath stream portion at a sheath sensing point therealong subsequent to the point of said perturbation for producing a surface character output signal which is proportional thereto; (ii) analyzing said surface character output signal to produce an analyzed output signal which is at least selectively responsive to said sheath sensing means; and (iii) adjusting the flow of at least a portion of said continuous particle containing stream at least in response to said analyzed output signal.
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Specification