Dimensionally-sensitive moisture sensor and an alarm system for an absorbent article

1. A sensor for detecting moisture in an absorbent article, the sensor comprising:

a housing made of material that is dimensionally-sensitive to a presence of moisture;

a plurality of electrically conductive contacts disposed on or in the housing;

wherein the electrically conductive contacts are selectively coupled to, or decoupled from, each other as a result of a dimensional change of the housing arising from exposure to moisture; and

wherein an electrical signal routable through the selectively coupled electrically conductive contacts creates a closed or an open circuit to indicate the presence of moisture.

2. The sensor of claim 1 wherein the housing has an outer surface and a cavity formed therein, and wherein the plurality of electrically conductive contacts is disposed on an inner wall of the cavity.

3. The sensor of claim 1 wherein:

the plurality of electrically conductive contacts are initially disposed apart from each other in a substantially dry environment to represent a normally open circuit that does not activate a moisture alarm; or

the plurality of electrically conductive contacts is initially disposed against each other in the substantially dry environment to represent a normally closed circuit that does not activate the moisture alarm.

4. The sensor of claim 1 wherein the housing is formed into a shape having a cylindrical, oval, or rectangular cross-section.

5. The sensor of claim 2 further comprising:

an outside layer disposed around the housing, wherein the outside layer helps to maintain a shape of the housing, and wherein the outside layer is a fibrous material disposed on the outer surface of the dimensionally-sensitive material in order to inhibit expansion of the outer surface of the housing and to promote closure of the cavity formed inside the housing.

6. The sensor of claim 1 wherein the dimensionally sensitive material used for the housing is highly compressed.

7. The sensor of claim 1 wherein at least a portion of the sensor is a consumable one-time use device that is at least partially biodegradable.

8. The sensor of claim 1 further comprising:

a plurality of electrically conductive leads, each of which is respectively coupled to one of the plurality of electrically conductive contacts;

wherein the electrically conductive contacts or the conductive leads therein are made from an electrically conductive polymer that is either at least partially biodegradable.

9. The sensor of claim 1 wherein the housing with dimensionally sensitive material expands at least 30% in the presence of moisture.

10. A system for detecting moisture, the system comprising:

a moisture-resistant layer;

an absorbent material coupled to the moisture-resistant layer;

a moisture sensor disposed in or on the absorbent material, wherein the sensor has a plurality of electrical contacts coupled thereto, and wherein the sensor detects moisture by changing a state of the plurality of electrical contacts from a normally open to a closed, or from a normally closed to an open position, under the force of mechanical expansion or contraction of the sensor in the presence of moisture;

a plurality of electrically conductive leads, wherein each of the electrically conductive leads is respectively coupled to one of the plurality of electrically conductive contacts on the moisture sensor; and

an alarm system coupled to the electrically conductive leads, wherein the alarm system is activated by the change of the state of the electrical contacts in the moisture sensor.

11. The system of claim 10 further comprising:

a plurality of moisture sensors for detecting moisture coupled to the alarm system, wherein any one of the plurality of moisture sensors can independently activate the alarm system due to detection of moisture.

12. The system of claim 11 wherein at least one of the plurality of moisture sensors, coupled via the electrically conductive leads to a unique alarm indicator, is disposed in a front of the diaper to detect urine.

13. The system of claim 11 wherein at least one of the plurality of moisture sensors, coupled via the electrically conductive leads to a unique alarm indicator, is disposed in the rear of the diaper to detect feces.

14. The system of claim 10 wherein the alarm system is selectively coupled to the electrically conductive leads such that the alarm system can be removed and reused, while the absorbent material and the moisture sensor can be discarded.

15. The system of claim 10 wherein the alarm device further comprises:

an alarm indicator coupled to the logic and the sensor, the alarm indicator producing an audio, visual, tactile, or data output when activated.

16. The system of claim 10 wherein the alarm device further comprises:

a connector having a plurality of brush contacts that selectively couple to the plurality of electrically conductive leads from the moisture sensor.

17. An alarm system for indicating a presence of moisture in an absorbent article, the alarm system comprising:

a sensor for detecting moisture, the sensor having a housing made of material dimensionally sensitive to the presence of moisture;

logic for determining when an electrical circuit coupled to the sensor changes from a normally open position to a closed position or from a normally closed position to an open position; and

a power source coupled to the logic.

18. The alarm system of claim 17 further comprising:

a wireless transmitter coupled to a battery and to a remote alarm indicator wherein the wireless transmitter has a duty cycle less than 50% for transmitting a signal to the remote alarm indicator device having audio, visual, tactile, or data indicating means for an alarm.

19. The alarm system of claim 17 further comprising:

an indicator chosen from a group of:

an operational indicator coupled to the logic and batter for indicating the operational status of the transmitter and the operational status of the battery source; and

an alarm indicator coupled to the logic and the sensor, the alarm indicator producing an audio, visual, tactile, or data output when activated.

20. The alarm system of claim 18 wherein the wireless transmitter can transmit at different frequencies for pairing with a specific alarm of a base receiving station.