Sensing element for use with media-preserving storage and calibration chamber
A sensor may include a sensing element retained within a storage compartment filled with a storage medium, which may also be used as a calibration medium. The sensing element can include a sensing surface located away from the distal end of the sensing element, such that an inactive section of the sensing element can cooperate with a sealing member such as an O-ring to form part of the seal retaining the storage/calibration medium. The sensing element can be extended and retracted from the storage compartment to expose the sensing surface to a process medium, while preserving the storage medium within the storage compartment for post-measurement validation.
1. A sensor structure, comprising:
a storage compartment configured to retain a storage medium therein;
a sensing element extending through an aperture in the compartment and comprising a sensing structure, a distal end of the sensing structure located proximal a distal end of the sensing element, the sensing element reversibly movable between a first position in which the sensing structure is in fluid communication within the storage compartment and a second position in which the sensing structure is not in fluid communication with the storage compartment, a proximal portion of the sensing element or of a movable component connected to the sensing element being located proximal and outside of the storage compartment when the sensing element is in the first position, the proximal portion located within the storage compartment when the sensing element is in the second position, the sensing element comprising a sensing surface substantially flush with adjacent surfaces of the sensing element, the sensing element comprising a section of substantially constant cross-sectional shape extending between a point proximal the proximal end of the sensing surface and a point distal the distal end of the sensing surface;
a sealing element disposed at least partially within the aperture and configured to engage a surface of the sensing element to provide a seal inhibiting fluid flow in or out of storage compartment through the aperture; and
a sterilizable and compressible compartment proximal the storage chamber and configured to retain the proximal portion when the sensing element is in the first position to maintain the sterility of the storage compartment when the proximal portion is moved into and out of the storage compartment.
2. The sensor structure of claim 1 , wherein the sensing element comprises a pH sensor.
3. The sensor structure of claim 1 , wherein the sensing structure is in electrical communication with a reference electrode.
4. The sensor structure of claim 1 , wherein the storage medium is configured to be used as a calibration medium for the sensing element.
5. The sensor structure of claim 1 , wherein translating the sensing element between the first position and the second position does not displace a substantial amount of the storage solution from the storage compartment, and does not expose the interior of the storage compartment.
6. The sensor structure of claim 1 , additionally comprising a second sensing element extending parallel to the first sensing element, wherein the second sensing element extends through a second aperture in the storage compartment and engages with a second sealing element disposed at least partially within the second aperture to provide a seal inhibiting fluid flow in or out of storage compartment through the second aperture.
7. The sensor structure of claim 1 , wherein the storage compartment comprises a first chamber and a second chamber, the sensing element extending through both the first chamber and the second chamber, wherein the sensing structure of the sensing element is within the first chamber when the sensing element is in the first position, and wherein the sensing element is longitudinally translatable to a third position in which the sensing structure is located within the second chamber, wherein the first chamber retains the storage solution, and wherein the second chamber retains a calibration medium, the calibration medium having a pH which is different from the pH of the storage solution.
8. The sensor structure of claim 1 , additionally comprising:
a movement detection mechanism configured to detect movement of the sensing element relative to the storage compartment, wherein the movement detection mechanism is configured to provide an indication of the time at which the detected movement occurred; and
a memory chip configured to record a timestamp movement of the sensing element relative to the storage compartment.
9. The sensor structure of claim 1 , wherein the sensing structure comprises a pH probe comprising a reference half-cell chamber and a measuring half-cell chamber, a sensing surface of the sensing structure comprising a glass pH electrode in fluid communication with the measuring half-cell chamber, the glass pH electrode located distal a distal end of the reference half-cell chamber.
10. The sensor structure of claim 1 , wherein the sensor structure additionally comprises a bellows structure defining the sterilizable and compressible compartment.
11. The sensor structure of claim 1 , wherein the sensor structure additionally comprises a sterile barrier defining the sterilizable and compressible compartment.
12. The sensor structure of claim 1 , wherein the sensing structure comprises a pH probe comprising a reference half-cell chamber and a measuring half-cell chamber, a sensing surface of the sensing structure comprising a glass pH electrode in fluid communication with the measuring half-cell chamber, the glass pH electrode located distal a distal end of the reference half-cell chamber.
13. The sensor structure of claim 1 , wherein the sensing element comprises a pH probe comprising a distal section comprising a substantially constant cross-sectional shape, the distal section comprising:
at least a portion of a reference half-cell chamber;
at least a portion of a measuring half-cell chamber;
an inert distal tip; and
a sensing surface in fluid communication with the measuring half-cell chamber and located distal a distal end of the reference half-cell chamber.
14. The sensor structure of claim 1 , wherein the sealing element comprises an aperture extending therethrough, a distal tip of the sensing element being positioned distal the sealing element when the sensing element is in the first position.
15. The sensor structure of claim 14 , wherein the sealing element comprises an O-ring.
16. The sensor structure of claim 14 , wherein the sealing element comprises a gasket.
17. The sensor structure of claim 1 , wherein a distal portion of the sealing element is exposed to the exterior of the sensor structure.
18. The sensor structure of claim 1 , wherein reversibly moving the sensing element between the first and second positions selectively exposes the sensing structure to a process medium on a distal side of the sealing element while maintaining the seal inhibiting fluid flow in or out of storage compartment through the aperture.
19. A sensor structure, comprising:
a storage compartment configured to retain a storage medium therein;
a sealing element disposed at least partially within an aperture in the storage compartment, the sealing element comprising an aperture extending therethrough;
a sensing element extending through the aperture in the sealing element, the sealing element configured to engage a surface of the sensing element to provide a seal inhibiting fluid flow in or out of storage compartment through the aperture in the storage compartment, the sensing element comprising a sensing surface substantially flush with adjacent surfaces of the sensing element, a distal end of the sensing surface located proximal a distal end of the sensing element, the sensing element comprising a section of substantially constant cross-sectional shape extending between a point proximal the proximal end of the sensing surface and a point distal the distal end of the sensing surface, the sensing element reversibly movable between:
a first position in which the sensing structure is in fluid communication within the storage compartment and a distal end of the sensing element is located distal of the sealing element, and
a second position in which the sensing structure is located distal of the sealing element, a proximal portion of the sensing element or of a movable component connected to the sensing element being located proximal and outside of the storage compartment when the sensing element is in the first position, the proximal portion located within the storage compartment when the sensing element is in the second position; and
a sterilizable and compressible compartment proximal the storage chamber and configured to retain the proximal portion when the sensing element is in the first position to maintain the sterility of the storage compartment when the sensing element is moved between the first and second positions to move the proximal portion into and out of the storage compartment.