Battery powered microprocessor controlled hand portable electronic pipette

• US 6,254,832 B1
• Filed: 03/08/1999
• Issued: 07/03/2001
• Est. Priority Date: 03/05/1999
• Status: Expired due to Term

• Current Assignee: Rainin Instrument LLC
• Original Assignee: Rainin Instrument LLC
• Inventors: Magnujssen, Haakon T. Jr., Homberg, William D., Kelly, Christopher, Rainin, Kenneth
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): Bex, Kathryn
• Application Number:
  US09/264,389
• Time in Patent Office: 848 Days
• Field of Search: 422/99, 422/100, 422/922, 422/925, 422/926, 422/931, 422/932, 456/180, 456/179, 738/630.1, 738/640.1, 738/641.1, 738/641.3, 738/641.6, 738/641.8
• US Class Current: 422/525
• CPC Class Codes: B01L 2200/087 Ergonomic aspects
• CPC Class Codes: B01L 2300/02 Identification, exchange or storage of information
• CPC Class Codes: B01L 2300/025 Displaying results or values with integrated means
• CPC Class Codes: B01L 2300/027 Digital display, e.g. LCD, LED
• CPC Class Codes: B01L 3/0227 Details of motor drive means B01L3/0231, B01L3/0234 take precedence
• CPC Class Codes: Y10T 436/25625 Dilution
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

A battery powered, microprocessor controlled portable electronic pipette, comprising a hand holdable housing supporting a battery, a linear actuator for driving a plunger lengthwise in a cylinder to aspirate and dispense fluid into and from a pipette tip extending from the housing and a control circuit for the linear actuator. The linear actuator is powered by the battery and comprises a stepper motor with current receiving windings for electromagnetically driving a rotor to impart the lengthwise movement to the plunger. The control circuit includes (i) a user controllable microprocessor powered by the battery and programmed to generate drive signals for the stepper motor, (ii) a display supported by the housing and electrically connected to the microprocessor, (iii) user actuateable control keys supported by the housing and electrically connected to the microprocessor for generating within the microprocessor pipette mode of operation, liquid pick up volume, liquid dispense, pipette speed of operation and pipette reset signals for controlling operation of the pipette and alpha-numeric user readable displays on the display, (iv) a memory having tables of data stored therein and accessible and useable by the microprocessor to control operations of the pipette, and (v) user actuateable switches supported by the housing for triggering pipette operations selected by user actuation of the control keys.

Claims

1. An electronic pipette, comprising:

a linear actuator for driving a plunger lengthwise in a cylinder to aspirate and dispense fluid into and from a pipette tip, the linear actuator comprising a motor with current receiving windings for electromagnetically driving a rotor to impart the lengthwise movement to the plunger; and

a control circuit for the pipette including a user controllable microprocessor programmed to generate drive signals for the motor, the control circuit further comprising

a display electrically connected to the microprocessor,

user actuateable control keys electrically connected to the microprocessor for generating within the microprocessor pipette mode of operation, liquid pick up volume, liquid dispense, pipette speed of operation and pipette reset signals for controlling operation of the pipette and alpha-numeric user readable displays on the display,

a memory having tables of data stored therein and accessible and useable by the microprocessor to control operations of the pipette, and

at least one user actuateable trigger switch for triggering pipette operations selected by user actuation of the control keys,

the microprocessor being further programmed to cause the pipette to sequentially enter successive user selected modes of operation in response to successive user actuation of only a first one of the control keys defining a “

mode”

-key and in each selected mode to control operation of the pipette so that

(a) actuation of an option key, defined by either a second distinctive actuation of the mode key or actuation of another of the control keys, causes the microprocessor to control the display to display at least a first operational option for the selected mode only, with subsequent actuations of the option key causing the display to sequentially display any other operational option for the selected mode only,

(b) actuation of a second one of the control keys defining an “

up”

key causes the microprocessor to control the display to indicate an activation or deactivation of the operational option as displayed by the display or an increasing value for a numeric display associated with the operational option in response to data from the tables stored in the memory, and

(c) actuation of a third one of the control keys defining a “

down”

key causes the microprocessor to control the display to indicate an activation or deactivation of the operational option as displayed by the display or a decreasing value for the numeric display associated with the operational option in response to data from the tables stored in the memory, and

(d) subsequent user actuations of the trigger switch actuates the motor to drive the plunger in the selected mode augmented by the operational options pursuant to (b) and (c) above and in an up direction to pick up liquid into the tip, and then in a down direction to dispense liquid from the pipette tip.

2. The pipette of claim 1 wherein the microprocessor is further programmed so that in each selected mode successive user actuations of the option key causes the microprocessor to control the display to sequentially display successive operational options for the selected mode only, each controllable pursuant to (b) and (c) of claim 1.

3. The pipette of claim 1 wherein the microprocessor is programmed so that the mode key functions as the option key to step between successive operational options in response to an initial sustained pressing of the mode key for a period of time longer than a momentary pressing of the mode key followed by successive momentary pressings of the mode key.

4. The pipette of claim 1 wherein the microprocessor is further programmed to control the display to exit the display of the operational options while remaining in the selected mode in response to user actuation of a fourth one of the control keys defining a “

reset”

key and or a subsequent sustained pressing of the mode key.

5. The pipette of claim 1 wherein the microprocessor is programmed so that a fourth one of the user actuateable control keys defines a “

reset”

-key.

6. The pipette of claim 5 wherein the microprocessor is further programmed so that the reset key forces a displayed parameter in the display to read zero in response to an initial sustained pressing of the reset key for a period of time longer than a momentary pressing of the reset key.

7. The pipette of claim 5 wherein the microprocessor is further programmed to enter a “

blow out”

operation in response to a momentary user actuation of the reset key to drive the plunger in the cylinder to blow fluid from the pipette tip.

8. The pipette of claim 5 wherein the microprocessor is further programmed so that each successive momentary user actuation of the reset key causes the microprocessor to control the display a to sequentially display different one of a plurality of successive operational parameters for editing by user actuation of the up or down keys.

9. The pipette of claim 1 wherein the microprocessor is further programmed to count and to control the display to distinctly display to the pipette user different displays for successive cycles of operation of the pipette in the selected mode of pipette operation thereby enabling the user to determine the operating cycle of the pipette for any period of pipette operation.

10. The pipette of claim 1 with a plurality of user actuateable trigger switches for triggering pipette operations selected by user actuation of the control keys,

wherein the microprocessor is further programmed to enter a manual mode of operation selected by user actuation of the mode key and in the manual mode to

(i) control operation of the pipette so that

(a) a first one of the trigger switches actuated by the user defines an “ up”

trigger actuation of which causes the microprocessor to control the motor to drive the plunger in a up direction to pick up liquid into the tip and

(b) a second one of the trigger switches actuated by the user defines a “

down”

trigger actuation of which causes the microprocessor to control the motor to drive the plunger in a down direction to dispense liquid from the tip and

(ii) to control the display to indicate the volume of liquid in the tip.

11. The pipette of claim 10 wherein the microprocessor is further programmed in the manual mode to,

(i) control operation of the pipette so that while at a home position with the plunger at a location ready to begin aspiration or pick up of liquid the display displays the maximum volume that can be picked up and,

(a) “

up”

key actuation causes the microprocessor to control the display to indicate an increasing value for a selected maximum volume of liquid to be picked up by the tip as the “

up”

key is actuated by the user and

(b) a “

down”

key actuation causes the microprocessor to control the display to indicate a decreasing value for the selected maximum volume of liquid to be picked up by the tip.

12. The pipette of claim 10 wherein the microprocessor is further programmed to increase the speed of liquid pick up and dispense as the up trigger and down trigger respectively are actuated by the user.

13. The pipette of claim 10 wherein one of the tables of data stored in the memory comprises correction factors for a maximum pick up volume associated with the pipette tip for reducing liquid volume errors associated with the pick up and dispensing of liquids by the pipette and wherein the correction factors are added to pick up and dispense movements of the motor to correct for the volume errors.

14. The pipette of claim 10 wherein the microprocessor is further programmed to count and to control the display to distinctly display to the pipette user different displays for successive cycles of operation of the pipette in the manual mode of pipette operation thereby enabling the user to determine the operating cycle of the pipette for any period of pipette operation.

15. The pipette of claim 10 wherein the microprocessor is further programmed to control the motor to enter a “

blow out”

wherein the motor drives the plunger beyond a home position to blow out liquid remaining in the tip after the plunger reaches the home position.

16. The pipette of claim 15 wherein the microprocessor is programmed to enter “

blow out”

in response to user actuation of one of the control keys or multiple actuation of the dispense trigger.

17. The pipette of claim 16 wherein the microprocessor is programmed to enter “

blow out”

operation in response to a momentary user actuation of a fourth one of the control keys defining a “

reset”

key.

18. The pipette of claim 17 wherein the microprocessor is further programmed so that the reset key forces the volume display to read zero in response to an initial sustained pressing of the reset key for a period of time longer than a momentary pressing of the reset key when the pipette is not at its home position,

wherein further up movement of the plunger from the position where the display is zeroed increases the volume reading and further down movement of the plunger from the zeroed position causes a negative volume to be displayed.

19. The pipette of claim 1 with a plurality of user actuateable trigger switches for triggering pipette operations selected by user actuation of the control keys, wherein the microprocessor is further programmed to enter a pipet mode of operation selected by user actuation of the mode key and in the pipet mode to

(i) control operation of the pipette so that

(a) up key actuation causes the microprocessor to control the display to indicate an increasing value for a selected volume of liquid to be picked up by the tip and

(b) down key actuation causes the microprocessor to control the display to indicate a decreasing value for the selected volume of liquid to be picked up by the tip and

(c) first user actuation of any of the trigger switches actuates the motor to drive the plunger in a up direction to pick up the selected volume of liquid into the tip and

(d) second user actuation of any of the trigger switches actuates the motor to drive the plunger in a down direction to dispense the selected volume of liquid from the tip.

20. The pipette of claim 19 wherein one of the tables of data stored in the memory comprises instructions for controlling the drive signals applied to the linear actuator to control the speed of operation of the motor in accordance with speed of operation settings selected by user actuation of the control keys.

21. The pipette of claim 19 wherein another of the tables of data stored in the memory comprises correction factors for various of the liquid pick up volume settings selected by user actuation of the control keys to control and eliminate liquid volume errors associated with the pick up and dispensing of liquids by the pipette.

22. The pipette of claim 19 wherein the microprocessor is programmed to count and to control the display to distinctly display to the pipette user different displays for successive cycles of operation of the pipette in the pipet mode of operation thereby enabling the user to determine the operating cycle of the pipette for any period of pipette operation.

23. The pipette of claim 19 wherein the microprocessor is further programmed to (i) pick up a second selected volume of liquid when the plunger reaches a home position for the plunger and in response to user actuation of one of the trigger switches as the plunger approaches the home position during dispensing of the selected volume of liquid and (ii) dispense and mix the second selected volume of liquid with the selected volume of liquid.

24. The pipette of claim 23 wherein the microprocessor is further programmed to repeat (i) and (ii) until none of the trigger switches are activated when the plunger nears the home position and to thereafter drive the motor to extend the plunger beyond the home position to blow out liquid from the tip.

25. The pipette of claim 1 with a plurality of user actuateable trigger switches for triggering pipette operations selected by user actuation of the control keys, wherein the microprocessor is further programmed to enter a multi mode of operation selected by user actuation of the mode key and in the multi mode to

(i) control operation of the pipette so that

(a) up key actuation causes the microprocessor to control the display to indicate an increasing value for a selected volume of liquid to be dispensed by the tip and

(b) down key actuation causes the microprocessor to control the display to indicate a decreasing value for the selected volume of liquid to be dispensed by the tip and

(c) a third one of the control keys defines a “

reset”

key, actuation of which causes the microprocessor to control the display to indicate a number corresponding to the number of aliquots of liquid of the selected volume that the pipette can dispense which number is adjustable by actuation of the “

up” and

“

down”

keys and

(d) first user actuation of any of the trigger switches actuates the motor to drive the plunger in a up direction to pick up into the tip a volume of liquid in excess of a volume equal to the selected volume times the number of aliquots of liquid to be dispensed by the pipette and

(e) second user actuation of any of the trigger switches actuates the motor to drive the plunger in a down direction to dispense the selected volume of liquid from the tip which is repeated for each second actuation of any of the trigger switches until the number of aliquots has been dispensed by the pipette.

26. The pipette of claim 25 wherein one of the tables of data stored in the memory comprises instructions for controlling the drive signals applied to the linear actuator to control the speed of operation of the motor in accordance with speed of operation settings selected by user actuation of the control keys.

27. The pipette of claim 25 wherein another of the tables of data stored in the memory comprises correction factors for various of the selected liquid volume settings selected by user actuation of the control keys to control and eliminate liquid volume errors associated with the pick up and dispensing of liquids by the pipette.

28. The pipette of claim 25 wherein the microprocessor is further programmed to control the motor to enter a “

blow out”

mode wherein the motor drives the plunger beyond a home position for the plunger to blow out liquid remaining in the tip after the plunger reaches the home position.

29. The pipette of claim 25 wherein the microprocessor is programmed so that step (a) and/or step (b) may be actuated prior to step (d) and/or after step (d) and prior to step (e) and/or after any actuation pursuant to step (e).

30. A microprocessor controlled hand held portable electronic pipette, comprising:

a hand holdable housing supporting a plunger, a cylinder, and a linear actuator for driving the plunger lengthwise in the cylinder to aspirate and dispense fluid into and from a pipette tip extending from the housing;

the linear actuator being powered by a battery contained in the housing or an external power source and comprising a stepper motor with current receiving windings for receiving drive signals for electromagnetically driving a rotor to impart the lengthwise movement to the plunger at controlled speeds through a series of microsteps; and

a control circuit for the pipette including a user controllable microprocessor powered by the battery or external power source and programmed to generate the drive signals for the stepper motor which are pulse width modulated (PWM) signals having duty cycles corresponding to different microstep positions for the stepper motor derived by the microprocessor from a first table of data stored in a memory included in the control circuit and having a repetition pattern derived by the microprocessor from a second table of data stored in the memory to determine the speed of motor movement, the control circuit further comprising

a display supported by the housing and electrically connected to the microprocessor, user actuateable control keys supported by the housing and electrically connected to the microprocessor for generating within the microprocessor pipette mode of operation, liquid pick up volume, liquid dispense, pipette speed of operation and pipette reset signals for controlling operation of the pipette and alphanumeric user readable displays on the display,

the memory having tables of data including the first and second tables stored therein and accessible and useable by the microprocessor to control operations of the pipette, and

a user actuateable switch supported by the housing for triggering pipette operations selected by user actuation of the control keys.

31. The pipette of claim 30 wherein the microprocessor is programmed so that the PWM drive signals have phases which do not overlap whereby there is no overlap of the PWM drive signals applied to the current receiving windings of the stepper motor.

32. The pipette of claim 30 wherein the battery or external power source develop a supply voltage, and the microprocessor is programmed to respond to the supply voltage in its selection of which of the tables of data stored in the memory it derives the duty cycles of the PWM drive signals.

36. The pipette of claim 33 defining a first pipette in combination with a second pipette as defined by claim 32 connected to the same power source having a current limit equal to or greater than the maximum charging current of the battery in the first and second pipettes wherein the microprocessor in each of the first and second pipettes is programmed to measure the power source voltage and determine its highest value (P_H) and its lowest value (P_L) during defined time intervals while the switch thereof is open and wherein each pipette while in its power management routine compares its measured P_L and P_H values to threshold values stored in its microprocessor to determine if it can charge its battery from the power source.

37. The pipettes in claim 36 where the charging to the batteries thereof can not take place unless the values of P_H and P_L therefor are greater than the respective threshold values.

38. The pipettes in claim 37 where the batteries are lithium ion batteries and the thresholds for P_L and P_H are greater than 4.6 and 4.9 volts respectively for battery charging to be allowed.

39. The pipettes in claim 38 where the time interval for determining P_L and P_H is greater than 1 ms but less than 100 ms.

33. A battery powered, microprocessor controlled hand held portable electronic pipette, comprising:

a hand holdable housing supporting a battery, a plunger, a cylinder and a linear actuator for driving the plunger lengthwise in the cylinder to aspirate and dispense fluid into and from a pipette tip extending from the housing;

the linear actuator being powered by the battery and comprising a motor with current receiving windings for receiving drive signals for electromagnetically driving a rotor to impart the lengthwise movement to the plunger; and

a control circuit for the pipette including a user controllable microprocessor powered by the battery and programmed to generate the drive signals for the motor, the microprocessor being further programmed to

(i) enter a power management routine on a periodic bases to check charge states of the battery and a power source for charging the battery having a current limit equal to or greater than a maximum charging current for the battery, and

(ii) open and close a switch between the power source and the battery,

the closed switch passing current at the current limit from the power source to the battery to charge the battery while a voltage generated by the power source is below a regulated value.

34. The pipette in claim 33 wherein the microprocessor is further programmed to generate a pulse width modulated switch control signal for opening and closing the switch such that the battery is charged with an average current equal to the duty cycle of the pulse width modulated control signal times the current limit from the power source.

35. The pipette in claim 34 wherein the microprocessor is further programmed to control the duty cycle of the pulse width modulated switch control signal to a value determined by the charge state of the battery.