EP-4735876-A1 - CONDENSATION MITIGATION IN IONIZATION SENSING

Abstract

An ionization sensor (110) includes a polarizing electrode (111), a signal electrode (117), a first dielectric layer (112) separating the signal electrode from the polarizing electrode and a heating element (114) configured to heat the polarizing electrode (111) and/or the signal electrode (117). A method for ionization sensing includes providing a detection cell and, through a window, illuminating the detection cell with ultraviolet light while heating the detection cell, the window, or both.

Inventors

• BAILEY, DOUGLAS

Assignees

• Applications Uniques Ltd.

Dates

Publication Date

20260506

Application Date

20240626

Claims (20)

1. 1 . An ionization detector, comprising: a polarizing electrode; a signal electrode; a first dielectric layer separating the signal electrode from the polarizing electrode; and a heating element configured to heat the polarizing electrode and/or the signal electrode.
2. 2. The ionization detector as set forth in claim 1 , wherein the heating element is provided between the first dielectric layer and the signal electrode.
3. 3. The ionization detector as set forth in claim 1 , wherein the heating element further comprises carbon fibers.
4. 4. The ionization detector as set forth in claim 1 , wherein a second dielectric layer separates the heating element from the signal electrode.
5. 5. The ionization detector as set forth in claim 4, wherein at least one of the first and second dielectric layers further comprise a fluoropolymer.
6. 6. The ionization detector as set forth in claim 4, wherein at least one of the first and second dielectric layers further comprise polytetrafluoroethylene.
7. 7. The ionization detector as set forth in claim 1 , further comprising a first fence electrode between the first dielectric layer and the heating element.
8. 8. The ionization detector as set forth in claim 7, further comprising a second fence electrode between the heating element and a second dielectric layer.
9. 9. The ionization detector as set forth in claim 1 , further comprising a fence electrode between the heating element and a second dielectric layer.
10. 10. The ionization detector as set forth in claim 1 , wherein the polarizing electrode, the signal electrode and the first dielectric layer comprise a detection cell and wherein a radiation source is provided to the detection cell.
11. 11 . The ionization detector as set forth in claim 1 , wherein the polarizing electrode, the signal electrode and the first dielectric layer comprise a detection cell and wherein an ultraviolet light is provided to the detection cell. The ionization detector as set forth in claim 1 , wherein the polarizing electrode, the signal electrode and the first dielectric layer comprise a detection cell and wherein a window is provided to the detection cell.
12. 12. The ionization detector as set forth in claim 1 , wherein the polarizing electrode, the signal electrode and the first dielectric layer comprise a detection cell and a wherein a radiation source is provided to the detection cell and a window is provided between the radiation source and the detection cell.
13. 13. The ionization detector as set forth in claim 1 , wherein the polarizing electrode, the signal electrode and the first dielectric layer comprise a detection cell and a wherein an ultraviolet light is provided to the detection cell and a window is provided between the ultraviolet light and the detection cell.
14. 14. The ionization detector as set forth in claim 1 , further comprising a hydration sensor and temperature control circuitry configured to adjust output of the heating element in accordance with a humidity level measured by the humidity sensor.
15. 15. A method for sensing ionization, comprising: providing a detection cell; through a window, illuminating the detection cell with ultraviolet light; and heating the detection cell, the window, or both.
16. 16. The method as set forth in claim 15, wherein the heating further comprises heating to a temperature sufficient to prevent condensation on the detection cell, the window, or both.
17. 17. The method as set forth in claim 15, wherein the heating further comprises heating continuously.
18. 18. The method as set forth in claim 15, wherein the heating further comprises maintaining a fixed heat output.
19. 19. The method as set forth in claim 15, wherein the heating further comprises heating with a carbon fiber heating element.
20. 20. The method as set forth in claim 15, wherein providing the detection cell further comprises providing a signal electrode layer bonded to a dielectric layer bonded to a polarizing electrode layer.

Description

CONDENSATION MITIGATION IN IONIZATION SENSING SUMMARY [0001 ]The disclosure describes an ionization detector. The ionization detector includes a polarizing electrode, a signal electrode, a first dielectric layer separating the signal electrode from the polarizing electrode and a heating element configured to heat the polarizing electrode and/or the signal electrode. [0002]The disclosure also describes a method for sensing ionization. The method includes providing a detection cell and, through a window, illuminating the detection cell with ultraviolet light. The detection cell, the window, or both are heated. [0003] Further, the disclosure describes an ionization sensor. The ionization sensor includes a detection cell, a window provided to the detection cell and a radiation source configured to illuminate portions of the detection cell through the window. The detection cell includes a polarizing electrode, a signal electrode, a first dielectric layer separating the signal electrode from the polarizing electrode, a heating element between the first dielectric layer and the signal electrode and a second dielectric layer separating the heating element from the signal electrode. [0004] Further still, the disclosure describes a method for manufacturing an ionization detector. The method includes providing a first half-cell having a polarizing electrode and a first dielectric layer, providing a second half-cell having a signal electrode and a second dielectric layer and sandwiching a heating element between the first and second half-cells. BRIEF DESCRIPTION OF THE FIGURES [0005]The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, example constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, one having skill in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers. [0006] Embodiments of the disclosure will now be described, by way of example only, with reference to the following diagrams wherein: [0007] FIG. 1 illustrates a top view of an example detection cell. [0008] FIG. 2 illustrates a bottom view of the example detection cell of FIG. 1 . [0009] FIG. 3 illustrates a top view of an example resistive heating layer. [0010] FIG. 4 illustrates a cross-sectional view of the example detection cell of FIGS. 1 & 2. [0011] FIG. 5 illustrates an exploded, cross-sectional view of the example detection cell of FIGS. 1-4. [0012] FIG. 6 illustrates a cross-sectional view of an example ionization sensor. [0013] FIG. 7 schematically illustrates an example ionization sensor system. DETAILED DESCRIPTION [0014]The following detailed description illustrates embodiments of the disclosure and manners by which they may be implemented. Although the best mode of carrying out embodiments of the disclosure has been disclosed, those skilled in the art would recognize that other embodiments are also possible. [0015] It should be noted that the terms "first", "second", and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. [0016] Ionization sensors and particularly photoionization sensors are used worldwide for measuring total volatile organic compounds (VOCs) in environmental monitoring applications. A photoionization sensor measures a current developed by VOC molecules ionized by a radiation source through a window. A relation between the current and the number of ionized molecules gives a measure of total VOC content in the local environment of the sensor. [0017] The detection cell within the photoionization detector (PID) typically has several layers of metal screens, metal plates or printed-circuit type electrodes separated by solid dielectric materials or air. These layers serve to efficiently collect signal from the charges liberated during photoionization of compounds within internal volumes of the detection cell. [0018] Existing photoionization sensors are vulnerable to effects from condensation of moisture. Due to the nature of their application, these sensors are exposed to environmental conditions which include almost daily condensing atmospheric conditions. Condensed moisture within the sensor causes various detrimental effects undermining analytical performance and causing premature failure of the device. Moisture may absorb radiation from the source reducing the amount of radiation available to produce a measurement signal, may create a conductive path between the electrodes and/or may obscure the radiation source, the window or both. Liquid water ca