Substance dispense system for biological sample analysis instrument
A substance dispense system is provided for a biological sample analysis instrument. The substance dispense system can operate to prepare a fluidic substance, such as a sample, using a dispense tip in different operational modes based on the volume of the fluid substance to be prepared. The substance dispense system thereby improves accuracy and/or precision in pipetting with the dispense tip.
1 . A method for preparing a liquid substance for evaluation, the method comprising:
aspirating a first volume of the liquid substance from a first vessel to a dispense tip; and
dispensing a second volume of the liquid substance from the dispense tip to a second vessel by:
lowering the dispense tip into the second vessel at a first height, the first height configured such that a distal end of the dispense tip remains above a liquid surface level in the second vessel;
dispensing part of the second volume of the liquid substance from the dispense tip to the second vessel at the first height such that the dispense tip retains a rest of the second volume of the liquid substance therein;
lowering the dispense tip to a second height, the second height configured such that the distal end of the dispense tip touches the liquid surface level in the second vessel; and
dispensing the rest of the second volume of the liquid substance from the dispense tip to the second vessel at the second height.
2 . The method of claim 1 , wherein dispensing a second volume of the liquid substance further comprises:
detecting, using a sensor, whether the liquid substance in the second vessel contacts the distal end of the dispense tip; and
transmitting a signal from the sensor to a control device, the signal usable by the control device to stop moving the dispense tip.
3 . The method of claim 1 , wherein the first volume is less than 30 μL, less than 25 μL, or less than 20 μL.
4 . The method of claim 1 , wherein the first volume is greater than the second volume.
5 . The method of claim 1 , wherein the second volume is greater than 25 μL.
6 . The method of claim 1 , wherein the first vessel comprises a sample vessel containing an aliquoted volume of the liquid substance and the second vessel comprises a reaction vessel.
7 . The method of claim 1 , further comprising:
rinsing the dispense tip using at least a portion of the liquid substance from the second vessel.
8 . The method of claim 7 , wherein rinsing the dispense tip comprises:
aspirating a third volume of the liquid substance from the second vessel to the dispense tip; and
dispensing a fourth volume of the liquid substance from the dispense tip to the second vessel.
9 . The method of claim 8 , further comprising:
dispensing the third volume of the liquid substance; and
again aspirating the third volume of the liquid substance.
10 . The method of claim 9 , further comprising repeating the steps of dispensing and aspirating the third volume.
11 . The method of claim 1 , wherein aspirating a first volume of the liquid substance comprises:
aspirating a fifth volume of the liquid substance from the first vessel to the dispense tip; and
dispensing a sixth volume of the liquid substance from the dispense tip to the first vessel to contain the first volume of the liquid substance in the dispense tip.
12 . The method of claim 11 , wherein the sixth volume is greater than the fifth volume.
13 . The method of claim 1 , wherein the first volume is equal to the second volume.
14 . The method of claim 1 , wherein the first vessel comprises a sample tube, or wherein the second vessel comprises a sample vessel, or both.
15 . The method of claim 1 , further comprising:
prior to aspirating the first volume of the liquid substance, determining a liquid surface level of the liquid substance contained in the first vessel.
16 . The method of claim 15 , wherein determining the liquid surface level of the liquid substance comprises:
lowering the dispense tip in to the first vessel;
detecting a pressure increase at a distal end of the dispense tip; and
calculating the liquid surface level of the liquid substance based on the pressure increase.
17 . The method of claim 16 , wherein calculating the liquid surface level of the liquid substance comprises:
determining a travel distance of the dispense tip until the pressure increase is detected; and
calculating the liquid surface level of the liquid substance based on the travel distance.
18 . The method of claim 16 , wherein determining the liquid surface level of the liquid substance further comprises:
prior to detecting a pressure increase, ejecting air from the dispense tip; and
after detecting the pressure increase and prior to aspirating the first volume, equalizing a pressure inside the dispense tip with the atmosphere.
19 . The method of claim 18 , wherein equalizing the pressure inside the dispense tip with the atmosphere comprises opening a valve arranged between the dispense tip and a syringe assembly.
20 . The method of claim 1 , wherein the liquid substance is an aqueous liquid substance.
21 . The method of claim 1 , wherein the dispensing the rest of the second volume at the second height is started within about 0.1 seconds of an end of the dispensing the part of the second volume at the first height.
22 . The method of claim 1 , wherein the dispense tip comprises a disposable dispense tip.