Method for controlling a magnetic valve and method for dispensing or aspirating a volume of liquid as well as corresponding dispenser/pipetting apparatus

Patent metadata

Field	Value
Publication number	US-11719355-B2
Application number	US-201917276731-A
Country	US
Kind code	B2
Filing date	Sep 20, 2019
Priority date	Sep 28, 2018
Publication date	Aug 8, 2023
Grant date	Aug 8, 2023

Abstract

A method for controlling a magnetic valve and particularly a method for dispensing and/or aspirating a volume of liquid as well as a corresponding dispenser/pipetting apparatus is disclosed. The method for controlling a magnetic valve has measuring a capacitance at the magnetic valve and determining a position of a plunger based on the measured capacitance. The method for dispensing or aspirating a volume of liquid has controlling a flow of a system fluid by a magnetic valve located between a pressure source and a dispenser/pipetting tip, dispensing or aspirating a volume of liquid through an exterior opening of the tip dependent on the flow of the system fluid, wherein controlling the flow and determining a flow time in dependence of the volume of liquid to be dispensed or aspirated, and controlling the magnetic valve is held open for the duration of the flow time.

First claim

The invention claimed is:

1. A method for controlling a magnetic valve ( 3 ), comprising a solenoid coil ( 13 ) and a mobile anchor forming a plunger ( 14 ), wherein the plunger ( 14 ) is moveable between a closed position (P c ) and an open position (P o ), the method comprising the steps of:
applying an opening current as a driving current to the solenoid coil ( 13 ) to drive the plunger ( 14 ) from the closed position (P c ) to the open position (P o );
measuring a capacitance of the magnetic valve ( 3 ) by applying a measuring voltage to the solenoid coil ( 13 );
determining a position (P) of the plunger ( 14 ) based on the capacitance measured of the magnetic valve ( 3 ).

2. The method of claim 1 , further comprising the step of:
holding the plunger ( 14 ) at a predetermined position (P) for a predetermined holding time (T h ) by applying a holding current as the driving current to the solenoid coil ( 13 ), the holding current having a smaller amplitude than the opening current.

3. The method of claim 1 , further comprising the step of:
applying a closing current as the driving current to the solenoid coil ( 13 ) to drive the plunger ( 14 ) from the open position (P o ) to the closed position (P c ), the closing current having an opposite polarity to the opening current.

4. The method of claim 1 , wherein the magnetic valve ( 3 ) further comprises a stationary anchor coaxially arranged adjacent to the mobile anchor, electrically connected to a metallic housing ( 17 ) of the magnetic valve ( 3 ), wherein the solenoid coil ( 13 ) and the housing ( 17 ) are connected to a capacitance measurement unit ( 11 ) for measuring the capacitance.

5. The method of claim 1 ,
wherein the measuring voltage is applied as an alternating current signal, a pseudo random noise signal or an exponential function shaped signal.

6. The method of claim 5 , wherein the measuring voltage has a different frequency than the driving current.

7. The method of claim 6 , wherein the measuring voltage has a different amplitude than a driving voltage associated with the driving current.

8. The method of claim 5 , wherein the measuring voltage is superimposed on the driving voltage associated with the driving current.

9. The method of claim 1 , wherein the driving current is applied as a pulse width modulated signal having a duty cycle consisting of an active phase and a passive phase, wherein the driving current is zero during the passive phase.

10. The method of claim 9 , wherein the measuring voltage is only present during the passive phase of the duty cycle of the pulse width modulated signal.

11. The method of claim 1 , further comprising the step of:
adjusting the driving current in dependence of the position (P) of the plunger ( 14 ).

12. The method of claim 1 , further comprising at least one of the following steps:
determining an opening time (T o ) of the magnetic valve ( 3 ) as a time interval between the plunger ( 14 ) leaving the closed position (P c ) and reaching the open position (P o );
determining a closing time (T c ) of the magnetic valve ( 3 ) as a time interval between the plunger ( 14 ) leaving the open position (P o ) and reaching the closed position (P c ),

and further comprising at least one of the following steps:
adjusting the driving current and the closing current in dependence of the opening time (T o ) and/or the closing time (T c );
providing a fault indication in dependence of the opening time (T o ) and/or the closing time (T c ).

13. The method according to claim 12 , comprising adjusting or calibrating a holding time (T h ) of the magnetic valve ( 3 ) in dependence of the determined opening time (T o ) and/or closing time (T c ).

14. The method according to claim 1 , comprising monitoring an operation of the magnetic valve ( 3 ) based on the position (P) of the plunger ( 14 ).

15. A method for dispensing or aspirating a volume of liquid ( 8 ) comprising the steps of:
applying a pressure from a pressure source ( 1 + , 1 − ) to a system fluid ( 9 );
controlling a flow of the system fluid ( 9 ) by means of a magnetic valve ( 3 ) located between the pressure source ( 1 + , 1 − ) and a tip ( 6 ) of a dispenser or pipette;
dispensing or aspirating the volume of liquid ( 8 ) through an exterior opening ( 7 ) of the tip ( 6 ) dependent on the flow of the system fluid ( 9 ), the system fluid ( 9 ) being in fluid communication with the liquid ( 8 ) to be dispensed or aspirated,

wherein controlling the flow comprises:
determining a flow time in dependence of the volume of liquid ( 8 ) to be dispensed or aspirated;
controlling the magnetic valve ( 3 ) by applying an opening current as a driving current to a solenoid coil ( 13 ) to drive a plunger ( 14 ) from a closed position (P c ) to an open position (P o ), measuring a capacitance of the magnetic valve ( 3 ) by applying a measuring voltage to the solenoid coil ( 13 ), determining a position (P) of the plunger ( 14 ) based on the measured capacitance, and holding the plunger ( 14 ) at a predetermined position (P) for a predetermined holding time (T h ) by applying a holding current as the driving current to the solenoid coil ( 13 ), the holding current having a smaller amplitude than the opening current,
wherein—the predetermined holding time (T h ) is set to the flow time.

16. The method of claim 15 , wherein a restrictor ( 4 ), such as a capillary, for restricting the flow is interconnected between the pressure source ( 1 + , 1 − ) and the tip ( 6 ), the restrictor ( 4 ) having a flow resistance which is at least twice that of the exterior opening ( 7 ) of the tip ( 6 ).

17. A dispenser/pipetting apparatus comprising:
a pressure source ( 1 + , 1 − ) adapted to apply a pressure to a system fluid ( 9 ), the system fluid ( 9 ) being in fluid communication with a liquid ( 8 ) to be dispensed or aspirated;
a magnetic valve ( 3 ); comprising a solenoid coil ( 13 ) and a mobile anchor forming a plunger ( 14 ), wherein the plunger ( 14 ) is moveable between a closed position (P c ) and an open position (P c );
a dispenser or pipetting tip ( 6 ) with an exterior opening ( 7 ) through which the liquid ( 8 ) can be dispensed or aspirated;
a capacitance measurement unit ( 11 ) adapted to measure a capacitance of the magnetic valve ( 3 ); and
a control unit ( 12 ) adapted to control a flow of the system fluid ( 9 ) by means of the magnetic valve ( 3 ), which is located between the pressure source ( 1 + , 1 − ) and the tip ( 6 ),

wherein the control unit ( 12 ) is adapted to:
determine a flow time in dependence of a volume of liquid ( 8 ) to be dispensed or aspirated; and
control the magnetic valve ( 3 ) by applying an opening current as a driving current to the solenoid coil ( 13 ) to drive the plunger ( 14 ) from the closed position (P c ) to the open position (P o ), measuring a capacitance of the magnetic valve ( 3 ) by applying a measuring voltage to the solenoid coil ( 13 ), determining a position (P) of the plunger ( 14 ) based on the measured capacitance, and holding the plunger ( 14 ) at a predetermined position (P) for a predetermined holding time (T h ) by applying a holding current as the driving current to the solenoid coil ( 13 ), the holding current having a smaller amplitude than the opening current,
wherein—the predetermined holding time (T h ) is set to the flow time.

18. The apparatus according to claim 17 , wherein the magnetic valve ( 3 ) further comprises a stationary anchor coaxially arranged adjacent to the mobile anchor,

Assignees

• Tecan Trading Ag
• Tegan Trading Ag

Inventors

• Ott Philipp

Classifications

• F16K31/0675 Primary

  Electromagnet aspects, e.g. electric supply therefor · CPC title

• B01L3/0293

  for liquids · CPC title

• F16K37/0083

  by measuring valve parameters · CPC title

• G01F11/12

  of the valve type, i.e. the separating being effected by fluid-tight or powder-tight movements (involving the tilting or inverting of the supply vessel G01F11/26) · CPC title

• G01F13/006

  measuring volume in function of time · CPC title