Method and apparatus for determing dispense volume
First Claim
1. A dispense volume sensor comprising:
- a dispense needle for dispensing a liquid sample; and
a receiving cylinder for receiving the dispense needle;
wherein said dispense needle and said receiving cylinder are arranged such that insertion of said dispense needle a certain distance into said receiving cylinder forms a capacitor to detect amounts of liquid located on the outside of said dispense needle after liquid has been aspirated into, or dispensed from, the dispense needle, wherein said dispense needle is made from electrically conducting materials or an outer surface of said dispense needle is electrically conductive.
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Accused Products
Abstract
In needle-based dispensing systems, the target amount of liquid to be dispensed is in many cases very well controlled. However, the amount of liquid that is actually reaching the receiving well may show a discrepancy, because part of the liquid leaving the inner needle space remains on the outer surface of the dispense needle, and so a small amount of liquid is “lost” in the dispensing act. A sensor arrangement according to the present invention is suitable for detecting the presence of any liquid from the aspiration reservoir that is left behind on the outside of the dispense needle, before the dispense step is actually started. The “lost” volume can also be measured very accurately by inserting the tip of a dispense needle into a hollow metallic cylinder, forming a capacitor, whereby the capacitance value depends on the volume of the “lost” dispense volume.
39 Citations
36 Claims
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1. A dispense volume sensor comprising:
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a dispense needle for dispensing a liquid sample; and a receiving cylinder for receiving the dispense needle; wherein said dispense needle and said receiving cylinder are arranged such that insertion of said dispense needle a certain distance into said receiving cylinder forms a capacitor to detect amounts of liquid located on the outside of said dispense needle after liquid has been aspirated into, or dispensed from, the dispense needle, wherein said dispense needle is made from electrically conducting materials or an outer surface of said dispense needle is electrically conductive. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A dispense volume sensor comprising:
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a plurality of dispense needles arranged in an array of at least one row and at least one column held in place by a first electrical insulating member, a plurality of receiving cylinders arranged in a matching array of at least one row and at least one column and supported by a second electrical insulating member, such that on insertion of said plurality of dispense needles a certain distance into said plurality of receiving cylinders a plurality of capacitors are formed to detect amounts of liquid located on the outside of the respective dispense needles after liquid has been aspirated into, or dispensed from, the respective dispense needles, wherein each of said dispense needles is made from electrically conducting materials or has an outer surface which is electrically conductive. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method to determine a volume of dispensed liquid comprising:
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introducing a target volume of a liquid sample into a dispense needle having a needle tip, said dispense needle being made from electrically conducting materials or an outer surface of said dispense needle being electrically conductive, dispensing an actual volume of said liquid sample from said dispense needle into a container, inserting said needle tip into a receiving cylinder a certain distance thereby forming a capacitor to detect amounts of liquid on the outside of said dispense needle, measuring the capacitance of said capacitor, and determining the presence of a lost volume of said dispensed liquid sample by comparing said measured capacitance value with a calibration capacitance value. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification