Composition pulse time-of-flight mass flow sensor
First Claim
1. A device for measuring the flow rate of a fluid in a flow channel, comprising:
- means for creating localized compositional variations in the fluid along the flow axis;
means for subsequently detecting the compositional variation at a point downstream from its point of creation; and
means for measuring flight time, wherein said device is capable of measuring flow rates from less than about 1 nL/min to greater than about 10 μ
L/min at pressures as great as 2,000 psi.
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Accused Products
Abstract
A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 μL/min) and at pressures at least as great as 2,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined. A pair of spaced apart electrodes can be used to produce the electrochemical pulse. In those instances where it is desired to measure a wide range of fluid flow rates a three electrode configuration in which the electrodes are spaced at unequal distances has been found to be desirable.
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Citations
40 Claims
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1. A device for measuring the flow rate of a fluid in a flow channel, comprising:
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means for creating localized compositional variations in the fluid along the flow axis; means for subsequently detecting the compositional variation at a point downstream from its point of creation; and means for measuring flight time, wherein said device is capable of measuring flow rates from less than about 1 nL/min to greater than about 10 μ
L/min at pressures as great as 2,000 psi. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A device for measuring fluid flow rates, comprising:
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a substrate fabricated to define a microchannel system disposed thereon, the microchannel system, in part, comprising; a flow channel; a pair of spaced-apart electrodes disposed along the fluid flow axis in the flow channel; means for applying a voltage pulse to said pair of electrodes, to produce a variation in the composition of the fluid; means for detecting the compositional variation; and means for measuring flight time. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A method for measuring fluid flow rates, comprising:
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providing a fluid flow channel; flowing fluid through the flow channel; producing a compositional variation in the fluid; detecting the compositional variation; and measuring the flight time of the variation.
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28. An electrode for electrokinetic systems, comprising:
an outer body fabricated from a microporous material and an inner metal electrode. - View Dependent Claims (29, 30)
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31. A device for measuring fluid flow rates, comprising:
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a substrate fabricated to define a microchannel system disposed thereon, the microchannel system, in part, comprising; a flow channel; at least three spaced-apart electrodes disposed along the fluid flow axis in the flow channel; means for applying a voltage pulse to pairs of electrodes, to produce a variation in the composition of the fluid; means for detecting the compositional variation; and means for measuring flight time. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification