Sensor for absorbent article
An absorbent structure, including a sensor system, can sense and measure the level of wetness contained within the absorbent structure as well as sense and measure environmental conditions. The sensor system may include passive RFID sensors or tags, RFID readers, antenna, a tuning module, a processing module, a memory module and a wireless communication module. The absorbent structure may further include two or more sensors, with a first sensor placed in a first area most likely to first be exposed to liquid and a second sensor spaced apart from the first sensor in an area likely to be exposed to liquid only after the absorbent structure has become more saturated.
1. An absorbent pad for covering a patient support structure, the absorbent pad comprising:
a periphery having a first portion and a second portion;
a liquid permeable layer;
a liquid impermeable base layer;
an absorbent layer positioned between the liquid permeable layer and the liquid impermeable layer;
a first sensor positioned between the liquid permeable layer and the liquid impermeable layer, the first sensor indicating when exudate is present at the first sensor; and
a second sensor positioned between the liquid permeable layer and the liquid impermeable layer, the second sensor indicating when exudate is present at the second sensor;
wherein the first sensor is positioned in a central portion of the absorbent pad and is not positioned adjacent to the periphery; and
wherein the second sensor is separated from the first sensor by a first distance, the second sensor is positioned adjacent to the first portion of the periphery and is not positioned adjacent to the second portion of the periphery, and the second sensor indicates that fluid has reached an edge of the patient support structure at the first portion of the periphery.
2. The absorbent pad of claim 1 , wherein the first sensor is positioned between the liquid permeable layer and the absorbent layer.
3. The absorbent structure of pad 7 , wherein the second sensor is positioned between the absorbent layer and the liquid impermeable layer.
4. The absorbent pad of claim 1 , wherein the first sensor is positioned between the absorbent layer and the liquid impermeable layer.
5. The absorbent pad of claim 1 , wherein the first sensor is positioned within the absorbent layer.
6. The absorbent pad of claim 5 , wherein the second sensor is positioned within the absorbent layer.
7. The absorbent pad of claim 1 , wherein the second sensor is positioned between the liquid permeable layer and the absorbent layer.
8. The absorbent pad of claim 1 , wherein the first sensor comprises a first RFID tag.
9. The absorbent structure of claim 8 , wherein the first RFID tag comprises a tail and an antenna coupled to the tail.
10. The absorbent structure of claim 9 , wherein the first RFID tag outputs information indicative an impedance value that varies with an environmental condition in which the antenna and the tail are placed.
11. The absorbent structure of claim 10 , wherein the environmental condition is an environmental condition selected from the group consisting of temperature, humidity, wetness, or proximity of an RFID reader to the RFID sensor.
12. The absorbent pad of claim 7 , wherein the second sensor comprises a second RFID tag separate from the first RFID tag.
13. The absorbent structure of claim 12 , wherein the second RFID tag comprises a second tail and a second antenna coupled to the second tail, and wherein the second RFID tag outputs information indicative an impedance value that varies with an environmental condition in which the second antenna and the second tail are placed.
14. An absorbent pad for covering a patient support structure and for absorbing a liquid emitted by a patient, the absorbent pad having a first area most likely to first be exposed to the liquid, the absorbent structure comprising:
a periphery having a first portion and a second portion separate and spaced apart from the first portion;
a liquid permeable layer;
a liquid impermeable layer;
an absorbent layer positioned between the liquid permeable layer and the liquid impermeable layer;
a first interior moisture sensor positioned between the liquid permeable layer and the liquid impermeable layer;
a first edge moisture sensor positioned between the liquid permeable layer and the liquid impermeable layer; and
a second edge moisture sensor positioned between the liquid permeable layer and the liquid impermeable layer;
wherein the first interior moisture sensor is positioned within the absorbent pad first area and the first sensor does not extend outside the first area;
wherein the first edge sensor is separated and isolated from the first interior sensor by a first distance, the first edge sensor is positioned outside the absorbent pad first area adjacent to the first portion of the periphery, and the first edge sensor indicating when fluid has reached a first edge of the patient support structure within the first portion of the periphery; and
wherein the second edge sensor is separated and isolated from the first interior sensor by a second distance and from the first edge sensor by a third distance, the second edge sensor is positioned outside the absorbent pad first area adjacent to the second portion of the periphery, and the second edge sensor indicating when fluid has reached a second edge of the patient support structure within the second portion of the periphery.
15. The absorbent pad of claim 14 , wherein the second edge sensor is not electrically connected with the first edge sensor.
16. The absorbent pad of claim 14 further comprising a second interior sensor spaced apart from the first interior sensor.
17. The absorbent pad of claim 14 , wherein the pad is integrated with a sheet.
18. The absorbent pad of claim 17 , wherein the sheet is formed by extending the liquid permeable layer beyond a perimeter of the liquid impermeable layer.
19. The absorbent pad of claim 17 , wherein the sheet comprises fitted corners.
20. The absorbent pad of claim 19 , wherein the fitted corners are formed by the liquid permeable layer.