WE CLAIM:
1. A wireless communication device comprising: a circuit unit; and an antenna
which is connected to said circuit unit and which transmits and receives signals to
and from a transceiver in a non-contact manner;
wherein said wireless communication device transmits different signals to said transceiver, depending on the presence or absence of contact between at least a part of said circuit unit and moisture.
2. The wireless communication device according to claim 1, wherein said circuit unit comprises an element formed using one or more materials selected from the group consisting of carbon nanotubes, graphene, fullerene and organic semiconductors, and wherein the properties of said element change due to contact with moisture.
3. The wireless communication device according to claim 2, wherein at least one parameter of the signal returned in response to the signal received from said transceiver changes, when the properties of said element change.
4. The wireless communication device according to claim 2 or 3,
wherein said element comprises a diode; and
wherein, when said diode comes into contact with moisture, said circuit unit transmits to said transceiver, a signal different from the signal to be transmitted when said diode is not in contact with moisture.
5. The wireless communication device according to claim 4,
wherein said diode is a variable capacity diode; and

wherein, when said variable capacity diode comes into contact with moisture, said circuit unit transmits to said transceiver, a signal having an intensity different from the intensity of the signal to be transmitted when said variable capacity diode is not in contact with moisture.
6. The wireless communication device according to claim 4 or 5,
wherein said circuit unit further comprises an oscillator circuit; and
wherein, when said diode comes into contact with moisture, said circuit unit
transmits to said transceiver, a signal having a frequency different from the frequency of the signal to be transmitted when said diode is not in contact with moisture.
7. The wireless communication device according to claim 6, wherein said
oscillator circuit comprises a ring oscillator.
8. The wireless communication device according to claim 2 or 3,
wherein said element is a ring oscillator; and
wherein, when said ring oscillator comes into contact with moisture, said circuit unit transmits to said transceiver, a signal having a frequency different from the frequency of the signal to be transmitted when said ring oscillator is not in contact with moisture.
9. The wireless communication device according to claim 2,
wherein said element is a memory element; and
wherein, when said memory element comes into contact with moisture, said circuit unit transmits to said transceiver, a signal different from the signal to be transmitted when said memory element is not in contact with moisture.

10. The wireless communication device according to any one of claims 2 to 9, wherein said element is formed using a carbon nanotube.
11. The wireless communication device according to any one of claims 2 to 10, wherein a semiconductor layer included in said element is formed using a carbon nanotube.
12. The wireless communication device according to claim 1, wherein said wireless communication device transmits signals including different information to said transceiver, depending on the presence or absence of contact between at least a part of wiring included in said circuit unit and moisture.
13. The wireless communication device according to claim 12,
wherein said circuit unit comprises a digital circuit; and
wherein, when at least a part of wiring of said digital circuit comes into contact with moisture, the properties of said digital circuit change, and said wireless communication device transmits to said transceiver, a signal including information different from the information included in the signal to be transmitted when at least a part of said wiring is not in contact with moisture.
14. The wireless communication device according to claim 12 or 13, wherein the electrical resistance of said wiring changes, when at least a part of said wiring comes into contact with moisture.
15. The wireless communication device according to any one of claims 12 to 14, wherein at least a part of said wiring comprises electrically conductive particles and a water-soluble resin.

16. The wireless communication device according to any one of claims 12 to 15, wherein at least a part of said wiring comprises a water-soluble electrically conductive polymer.
17. The wireless communication device according to any one of claims 12 to 14, wherein at least a part of said wiring comprises electrically conductive particles and a water-absorbent resin.
18. The wireless communication device according to any one of claims 12 to 14,
wherein at least a part of said wiring is provided on a layer containing a
water-soluble resin; and
wherein the electrical resistance of said wiring changes, when said layer comes into contact with moisture.
19. The wireless communication device according to any one of claims 12 to 14,
wherein at least a part of said wiring is provided on a layer containing a
water-absorbent resin; and
wherein the electrical resistance of said wiring changes, when said layer comes into contact with moisture.
20. The wireless communication device according to any one of claims 12 to 19,
wherein said circuit unit comprises:
a memory element which is connected to said wiring and which stores predetermined information; and
a control circuit which reads information from said memory element and transmits the information to said transceiver;

and
wherein the information to be read by said control circuit from said memory element varies depending on the presence or absence of contact between said wiring and moisture.
21. The wireless communication device according to any one of claims 12 to 19,
wherein said circuit unit comprises:
a plurality of memory elements arranged in the form of an array; and a control circuit which reads information from said plurality of
memory elements and transmits the information to said transceiver;
and
wherein the information to be read by said control circuit from said plurality
of memory elements varies depending on the presence or absence of contact between
said wiring and moisture.
22. A diaper comprising:
a water absorbent material which absorbs and retains moisture; and
a waterproof material having a waterproof function and covering said water absorbent material;
wherein said diaper is capable of being attached to a human body and absorbing moisture released from the human body; and
wherein said diaper comprises the wireless communication device according to any one of claims 1 to 21.
23. The diaper according to claim 22, wherein said wireless communication
device is positioned between said water absorbent material and said waterproof
material.

24. A moisture detection system, comprising:
the wireless communication device according to any one of claims 1 to 21; and
a transceiver which is capable of communicating with said wireless communication device in a non-contact manner, and which detects the presence or absence of contact between said wireless communication device with moisture, based on the signal returned in response to the signal transmitted to said wireless communication device.
25. The moisture detection system according to claim 24, wherein said
transceiver transmits a signal having a frequency in the UHF band or the microwave
band.
26. The moisture detection system according to claim 24 or 25,
wherein said wireless communication device is provided in a diaper
comprising:
a water absorbent material which absorbs and retains moisture; and a waterproof material having a waterproof function and covering said
water absorbent material; and
wherein said diaper is capable of being attached to a human body and
absorbing moisture released from the human body.