Capillary emitter with electrospray ionizaiton providing femtoliter to nanoliter flow rates

Patent metadata

Field	Value
Publication number	US-2025391651-A1
Application number	US-202519307154-A
Country	US
Kind code	A1
Filing date	Aug 22, 2025
Priority date	May 13, 2020
Publication date	Dec 25, 2025
Grant date	—

Abstract

The present disclosure relates to an apparatus and method to achieve electrospray ionization at femtoliter/minute to nanoliter/minute flow rates including relatively rapid alternation between such flow rates within the same device. These flow rates provide enhanced and relatively more uniform ionization of sprayed compounds for subsequent analytical evaluations.

First claim

1 . A device for delivery of a liquid sample at an adjustable capillary liquid flow rate comprising:
a capillary emitter having an outlet tip and including an extended component affixed to an inner wall of the capillary emitter to provide at least one sub-channel for fluid flow within the capillary emitter; a plasma discharge source to provide plasma ions; and an electric field source configured to direct the plasma ions to the outlet tip, the electric field source including at least one pusher electrode coupled to a voltage source by a switch, the voltage source configured to provide a supply voltage to the at least one pusher electrode; wherein the adjustable capillary liquid flow rate at the outlet tip is alternated between a relatively lower flow rate of femtoliters per minute (fL/min) and a relatively higher flow rate of nanoliters per minute (nL/min) by operating the switch to selectively enable and disable provision of the supply voltage to the at least one pusher electrode.

2 . The device of claim 1 , wherein the capillary emitter comprises an elongate body including the inner wall and an outer wall, the outlet tip being positioned at one end of the elongate body; and
wherein the extended component extends along a length of the capillary emitter.

3 . The device of claim 2 , wherein the extended component has an outer diameter that is smaller than an opening diameter of the outlet tip; and
wherein the capillary emitter is configured to guide the liquid sample to the outlet tip at least in part by capillary action.

4 . The device of claim 3 , wherein the electric field source is configured to direct the plasma ions to the outlet tip to provide a plasma-liquid contact at the outlet tip and thereby maintain a liquid level of the liquid sample at the outlet tip that is smaller than the opening diameter of the outlet tip.

5 . The device of claim 1 , wherein the adjustable capillary liquid flow rate at the outlet tip is in the range of 50 fL/min to 500 nL/min.

6 . The device of claim 5 , wherein the adjustable capillary liquid flow rate at the outlet tip is alternated between a relatively lower flow rate of picoliters per minute (pL/min) and the relatively higher flow rate of nL/min.

7 . The device of claim 6 , wherein the adjustable capillary liquid flow rate at the outlet tip is in the range of 50 pL/min to 150 nL/min.

8 . The device of claim 1 , wherein the extended component is a glass rod.

9 . The device of claim 1 , wherein the supply voltage is a in a range of 0-5 kilo Volts (kV) with either positive polarity or negative polarity.

10 . The device of claim 1 , wherein the device is configured to alternate the adjustable capillary liquid flow rate between the relatively lower flow rate of fL/min and the relatively higher flow rate of nL/min over a period of 10 microseconds to 1.0 second.

11 . A method of delivering a liquid sample at an adjustable flow rate, the method comprising:
introducing a liquid sample into a capillary emitter having an extended component affixed to an inner wall of the capillary emitter to provide one or more sub-channels for fluid flow within the capillary emitter, and the capillary emitter configured to direct the liquid sample to an outlet tip of the capillary emitter via capillary action along the inner wall and/or the extended component; operating a plasma discharge source to form plasma ions; generating an electric field to direct the plasma ions to an outlet tip of a capillary emitter; maintaining a liquid level of the liquid sample at the outlet tip that is smaller than the opening diameter of the emitter tip; and alternating the adjustable flow rate at the outlet tip between a relatively lower flow rate of femtoliters per minute (fL/min) and a relatively higher flow rate of nanoliters per minute (nL/min).

12 . The method of claim 11 , wherein generating the electric field comprises operating a voltage source to provide a supply voltage to at least one pusher electrode to cause the at least one pusher electrode to generate the electric field.

13 . The method of claim 12 , wherein alternating the adjustable flow rate comprises selectively enabling and disabling provision of the supply voltage to the at least one pusher electrode.

14 . The method of claim 11 , wherein the adjustable flow rate at the outlet tip is in the range of 50 fL/min to 500 nL/min.

15 . The method of claim 11 , wherein alternating the adjustable flow rate comprises alternating the adjustable flow rate between a relatively lower flow rate of picoliters per minute (pL/min) and the relatively higher flow rate of nL/min.

16 . The method of claim 15 , wherein the adjustable flow rate at the outlet tip is in the range of 50 pL/min to 150 nL/min.

17 . The method of claim 11 , wherein alternating the adjustable flow rate comprises alternating the adjustable flow rate between the relatively lower flow rate of fL/min and the relatively higher flow rate of nL/min over a period of 10 microseconds to 1.0 second.

18 . A method of delivery of a liquid sample at an adjustable flow rate, the method comprising:
providing a capillary emitter having an outlet tip and including inner and outer walls and an extended component affixed to the inner wall of the capillary emitter to provide one or more sub-channels for fluid flow, operating a plasma discharge source to form plasma ions; operating an electric field source to provide an electric field to direct the plasma ions to the outlet tip of the capillary emitter; introducing a liquid sample into the capillary emitter; providing at the outlet tip of the capillary emitter, a liquid sample flow rate in the range of 50 femtoliters/minute (fL/min) to 500 nanolters/minute (nL/min); and controlling the electric field source to alternate the liquid sample flow rate between a relatively lower flow rate of fL/min and a relatively higher flow rate of nL/min.

19 . The method of claim 18 , wherein the electric field source comprises at least one pusher electrode and a voltage source configured to provide a supply voltage to at least one pusher electrode; and
wherein controlling the electric field source to alternate the liquid sample flow rate comprises selectively enabling and disabling provision of the supply voltage to the at least one pusher electrode.

20 . The method of claim 18 , wherein providing the liquid sample flow rate comprises providing, at the outlet tip of the capillary emitter, the liquid sample flow rate in the range of 50 picoliters/minute (pL/min) to 150 nL/min; and
wherein controlling the electric field source comprises controlling the electric field source to alternate the liquid sample flow rate between a relatively lower flow rate of pL/min and the relatively higher flow rate of nL/min.

Assignees

• Univ New Hampshire
• Thermo Finnigan Llc

Inventors

• Li Anyin
• Li Linfan
• Li Mengtian

Classifications

• B05B5/0255

  spraying and depositing by electrostatic forces only · CPC title

• H01J49/167 Primary

  Capillaries and nozzles specially adapted therefor; (electrostatic spraying per se B05B5/00) · CPC title