1. A flextensional transducer, comprising in combination:
a generally disc-shaped piezoelectric member having a generally flat top surface and a generally flat parallel bottom surface;
a top electrode formed on the top surface;
a bottom electrode formed on the bottom surface;
a top endcap operationally connected to the top surface; and
a bottom endcap operationally connected to the bottom surface;
wherein the top and bottom endcaps are formed of shape memory material; and
wherein the endcap exerts a radial stress upon the generally disc-shaped piezoelectric member.
2. The transducer of claim 1 wherein the radial stress on the disc-shaped piezoelectric member yields an increase in its dielectric constant by at least about 50%.
3. The transducer of claim 1 wherein the radial stress on the disc-shaped piezoelectric member yields an increase in its dielectric constant by at least about 70%.
4. The transducer of claim 1 wherein the radial stress on the disc-shaped piezoelectric member yields an increase in its displacement response of at least about 30%.
5. The transducer of claim 4 wherein the radial stress on the disc-shaped piezoelectric member yields an increase in its domain wall translation contribution to displacement response.
6. The transducer of claim 1 wherein each respective endcap is bonded to a respective electrode and wherein each respective electrode is bonded to a respective surface.
7. A method of making a flextensional transducer device, comprising:
a) configuring a piece of shape memory material having an initial shape into a first endcap having a final shape;
b) coupling the first endcap to a piezoelectric member; and
c) initiating recovery of the initial shape of the shape memory material;
wherein recovery of the initial shape of the shape memory material generates radial stresses in the piezoelectric member.
8. The method of claim 7 wherein the piezoelectric member is pre-poled.
9. The method of claim 7 wherein 90 degree domain switching of the piezoelectric member is substantially enhanced by the radial stresses generated therein.
10. The method of claim 7 wherein the dielectric constant of the piezoelectric member is substantially enhanced by the radial stresses generated therein.
11. The method of claim 7 and further comprising:
d) forming an electrode layer on the piezoelectric member; and
e) bonding the first endcap to the electrode layer.
12. The method of claim 7 and further comprising:
f) configuring a second piece of shape memory material having an initial shape into a second endcap having a final shape; and
g) bonding the second endcap to the piezoelectric member opposite the first endcap.
13. The method of claim 7 wherein the shape memory material is nitinol and wherein the piezoelectric member is a PZT.
14. The method of claim 7 wherein the piezoelectric material is near it morphotropic phase boundary at standard temperature and pressure.
15. A method of making a transducer device, comprising:
a) forming a pair of endcaps from shape memory material, wherein the shape memory material has an initial shape and the endcaps define a final shape;
b) coupling the endcaps to opposite sides of a generally flat piezoelectric member to define a transducer device; and
c) inducing radial stresses in the piezoelectric material to yield a pre-stressed flextensional transducer device;
wherein recovery of the initial shape of the endcaps induces radial stress in the piezoelectric member.
16. The method of claim 15 wherein the shape memory material is nitinol and wherein the piezoelectric member is substantially PZT.
17. The method of claim 15 wherein the induction of radial stress is accomplished by exposing the endcaps to conditions sufficient to initiate a shift from their final shape towards their initial shape.
18. The method of claim 17 wherein the endcaps are nitinol and the conditions include an increase in temperature to at least about 45 degrees Celsius.
19. The method of claim 15 wherein induction of radial stresses in the piezoelectric member is accompanied by an increase in its dielectric constant of at least about 70%.
20. The method of claim 15 wherein the induction of radial stress on the piezoelectric member yields an increase in its displacement response of at least about 30%.
21. The transducer of claim 15 wherein the induction of radial stress on the piezoelectric member yields a substantial increase in the efficiency of the flextensional transducer device.
22. The transducer of claim 15 wherein the induction of radial stress on the piezoelectric member yields an effective increase in d33 piezoelectric charge coefficient of at least about 50%.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A computer-implemented method of performing a commercial transaction between a first entity and a second entity, comprising the steps of:
receiving, by an account server from the first entity, an account number and a verification code, wherein the account number and the verification code are selected by the first entity, and wherein the account number relates to a first account maintained by the account server;
verifying, by the account server, the account number and the verification code;
receiving, by the account server from the second entity, information regarding a specific transaction; and
adjusting, by the account server, the first account and a second account according to the specific transaction, wherein the second account is related to the second entity.
2. The method of claim 1, wherein the account number corresponds to a mobile telephone number of a mobile telephone of the first entity.
3. The method of claim 1, further comprising:
sending, by the account server, a verification of the specific transaction to a personal communications device of the first entity, wherein the account number directly identifies the personal communications device.
4. The method of claim 1, wherein the first account is one of a plurality of accounts related to the account number and maintained by the account server.
5. A computer-implemented method of transferring funds from a first entity to a second entity, comprising the steps of:
receiving, by an account server from the first entity, a first account number and a verification code, wherein the first account number and the verification code are selected by the first entity, and wherein the first account number relates to a first account maintained by the account server;
verifying, by the account server, the first account number and the verification code;
receiving, by the account server from the first entity, a second account number and a transaction amount, wherein the second account number is selected by the second entity and relates to a second account maintained by the account server; and
adjusting, by the account server, the first account and the second account according to the transaction amount.
6. A method of funding a gift certificate, comprising the steps of:
receiving information indicating an account number and a funding source, wherein the account number is selected by a first entity, and wherein the account number corresponds to an account related to the first entity;
funding the account according to the funding source; and
transmitting a verification of completion of the step of funding to a personal communications device of the first entity, wherein the account number directly identifies the personal communications device.
7. The method of claim 6, further comprising:
receiving a merchant identifier, wherein the step of funding the account comprises funding a sub-account of the account that is related to the merchant identifier.
8. An apparatus including an account server for performing a commercial transaction between a first entity and a second entity, said account server executing a computer program comprising the steps of:
receiving, from the first entity, an account number and a verification code, wherein the account number and the verification code are selected by the first entity, and wherein the account number relates to a first account maintained by the account server;
verifying, the account number and the verification code;
receiving, from the second entity, information regarding a specific transaction; and
adjusting, the first account and a second account according to, the specific transaction, wherein the second account is related to the second entity.
9. A system for performing a commercial transaction between a first entity and a second entity, comprising:
an account server; and
an input device, coupled to said account server via a network,
wherein said account server executes a first computer program comprising the steps of:
receiving, from the input device, an account number and a verification code, wherein the account number and the verification code are selected by the first entity, and wherein the account number relates to a first account maintained by the account server;
verifying the account number and the verification code;
receiving information regarding a specific transaction; and
adjusting the first account and a second account according to the specific transaction, wherein the second account is related to the second entity; and
wherein said input device executes a second computer program comprising the steps of:
receiving, from said first entity, said account number and said verification code; and
transmitting said account number and said verification code to said account server via said network.
10. The system of claim 9, wherein said input device comprises a first input device, further comprising:
a second input device, coupled to said account server via said network, wherein said second input device executes a third computer program comprising the steps of:
receiving, from said second entity, said information regarding said specific transaction; and
transmitting said information regarding said specific transaction to said account server via said network.