Electronic pipettor with improved accuracy
First Claim
1. In a hand-held electronic pipettor having an aspiration cylinder and piston, a stepper motor that drives the piston in the aspiration cylinder, a microprocessor, and a user interface display, a method of aspirating and dispensing liquid volumes comprising the steps of:
- selecting an aspiration volume;
using an aspiration lookup table to determine a number of motor steps necessary to aspirate the selected aspiration volume, wherein values in the aspiration lookup table representing the number of motor steps necessary to aspirate respective volumes are determined empirically to account for aspiration inaccuracies in the pipettor;
instructing the motor to move the piston to a home position and then instructing the motor to retract the piston the determined number of motor steps in order to aspirate the selected aspiration volume into a disposable pipettor tip mounted to the pipettor;
selecting a dispensing volume;
using a dispensing lookup table to determine a number of motor steps necessary to dispense the selected volume, wherein the values of motor steps necessary to dispense respective volumes in the dispensing lookup table are determined empirically to account for dispensing inaccuracies;
instructing the motor to extend the piston the determined number of motor steps in order to dispense the selected dispense volume from the disposable pipettor tip mounted to the pipettor.
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Accused Products
Abstract
A hand-held electronic pipettor is designed particularly to be programmed and operated with one hand for the convenience of the user. It uses a capacitance touchpad control for programming, and a separate run button for the operating mode. Internal components are located so that the center of gravity of the pipettor is located within the palm of the user. Flash memory stores an empirically derived table that correlates aspiration volume to motor steps and a separate empirically derived table the correlates dispensing volumes to motor steps.
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Citations
9 Claims
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1. In a hand-held electronic pipettor having an aspiration cylinder and piston, a stepper motor that drives the piston in the aspiration cylinder, a microprocessor, and a user interface display, a method of aspirating and dispensing liquid volumes comprising the steps of:
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selecting an aspiration volume; using an aspiration lookup table to determine a number of motor steps necessary to aspirate the selected aspiration volume, wherein values in the aspiration lookup table representing the number of motor steps necessary to aspirate respective volumes are determined empirically to account for aspiration inaccuracies in the pipettor; instructing the motor to move the piston to a home position and then instructing the motor to retract the piston the determined number of motor steps in order to aspirate the selected aspiration volume into a disposable pipettor tip mounted to the pipettor; selecting a dispensing volume; using a dispensing lookup table to determine a number of motor steps necessary to dispense the selected volume, wherein the values of motor steps necessary to dispense respective volumes in the dispensing lookup table are determined empirically to account for dispensing inaccuracies; instructing the motor to extend the piston the determined number of motor steps in order to dispense the selected dispense volume from the disposable pipettor tip mounted to the pipettor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification