RFID antenna for in-body device
RFID antennas for ingestible devices, such as ingestible event markers, are provided. Aspects of the ingestible devices of the invention include RFID signal transmission antennas with a battery that is activated upon being exposed to fluid in the body. Embodiments of the RFID antennas are configured to emit a detectable signal upon contact with a target physiological site. Also provided are methods of making and using the devices of the invention.
1. An ingestible event marker comprising:
an identifier operative to emit a signal when activated at a target site, wherein the identifier comprises a signal generation circuit comprising a radio frequency identification (RFID) antenna, wherein the signal generation circuit comprises a voltage controlled oscillator (VCO) and a digital control circuit coupled to the VCO, the digital control circuit assigned an address, the digital control circuit to control the VCO with a control signal associated with the address;
wherein the digital control circuit further comprises:
a digital counter circuit comprising an input portion coupled to the VCO and an output portion, wherein the VCO is operative to generate a first clock signal and a second clock signal, wherein the second clock signal is an inverted version of the first clock signal, and wherein the first and second clock signals are coupled to the digital counter circuit, wherein the digital counter circuit is operative to count a number of clock cycles received from the VCO, store the count in at least one register, and provide the count to the output portion of the digital counter circuit.
2. The ingestible event marker according to claim 1 , wherein the identifier is activated upon contact with fluid at the target site.
3. The ingestible event marker according to claim 2 , wherein the target fluid is stomach fluid.
4. The ingestible event marker according to claim 1 , wherein the identifier comprises a power source.
5. The ingestible event marker according to claim 4 , wherein the power source comprises a battery.
6. The ingestible event marker according to claim 4 , wherein the power source comprises a Galvanic cell.
7. The ingestible event marker according to claim 1 , wherein an input signal to the RFID antenna is provided by a reader.
8. The ingestible event marker according to claim 1 , wherein an input signal to the RFID antenna is provided by a battery.
9. The ingestible event marker according to claim 1 , wherein the identifier has a limited lifespan.
10. The ingestible event marker according to claim 1 , wherein the RFID antenna is configured to conform to ingestible pill dimensions.
11. The ingestible event marker according to claim 1 , wherein the RFID antenna has a first configuration prior to ingestion and a second configuration after ingestion.
12. The ingestible event marker according to claim 11 , wherein the RFID antenna unfolds after ingestion.
13. The ingestible event marker according to claim 11 , wherein the RFID antenna has a greater effective area in the second configuration than in the first configuration.
14. The ingestible event marker according to claim 1 , wherein the identifier comprises an integrated circuit.
15. The ingestible event marker according to claim 1 , further comprising an active agent stably associated with the signal generation circuit.
16. A system comprising:
(a) an ingestible event marker comprising an identifier operative to emit a signal when activated at a target site, wherein the identifier comprises a signal generation circuit comprising a radio frequency identification (RFID) antenna, wherein the signal generation circuit comprises a voltage controlled oscillator (VCO) and a digital control circuit coupled to the VCO, the digital control circuit assigned an address, the digital control circuit to control the VCO with a control signal associated with the address, wherein the digital control circuit further comprises:
a digital counter circuit comprising an input portion coupled to the VCO and an output portion, wherein the VCO is operative to generate a first clock signal and a second clock signal, wherein the second clock signal is an inverted version of the first clock signal, and wherein the first and second clock signals are coupled to the digital counter circuit, wherein the digital counter circuit is operative to count a number of clock cycles received from the VCO, store the count in at least one register, and provide the count to the output portion of the digital counter circuit; and
(b) a receiver configured to detect a signal produced by the signal generation circuit.
17. The system according to claim 16 , wherein the receiver is an in vivo receiver.
18. The system according claim 16 , wherein the receiver is an ex vivo receiver.
19. A method comprising:
administering to a subject an ingestible event marker comprising an identifier operative to emit a signal when activated at a target site, wherein the identifier comprises a signal generation circuit comprising a radio frequency identification (RFID) antenna, a voltage controlled oscillator (VCO) and a digital control circuit coupled to the VCO, the digital control circuit assigned an address;
generating a digital clock signal in response to activation of the identifier to vary the frequency of the VCO; and
controlling the VCO by the digital control circuit with a control signal associated with the address;
wherein controlling the VCO comprises:
generating a first clock signal and a second clock signal, wherein the second clock signal is an inverted version of the first clock signal, and wherein the first and second clock signals are coupled to a digital counter circuit comprising an input portion coupled to the VCO and an output portion;
counting by the digital counter circuit a number of clock cycles received from the VCO;
storing the count in at least one register; and
providing the count to the output portion of the digital counter circuit.
20. A kit comprising:
at least one ingestible event marker comprising an identifier operative to emit a signal when activated at a target site, wherein the identifier comprises a signal generation circuit comprising a radio frequency identification (RFID) antenna, wherein the signal generation circuit comprises a voltage controlled oscillator (VCO) and a digital control circuit coupled to the VCO, the digital control circuit assigned an address, the digital control circuit to control the VCO with a control signal associated with the address;
wherein the digital control circuit further comprises:
a digital counter circuit comprising an input portion coupled to the VCO and an output portion, wherein the VCO is operative to generate a first clock signal and a second clock signal, wherein the second clock signal is an inverted version of the first clock signal, and wherein the first and second clock signals are coupled to the digital counter circuit, wherein the digital counter circuit is operative to count a number of clock cycles received from the VCO, store the count in at least one register, and provide the count to the output portion of the digital counter circuit.
21. The kit according to claim 20 , wherein the kit comprises a plurality of the ingestible event markers.
22. The kit according to claim 20 , wherein the kit further comprises a receiver.
23. An in-body device comprising:
a radio frequency identification (RFID) antenna; and
an identifier operative to emit a signal when activated at a target site, wherein the identifier comprises a signal generation circuit, wherein the signal generation circuit comprises a voltage controlled oscillator (VCO) and a digital control circuit coupled to the VCO, the digital control circuit assigned an address, the digital control circuit to control the VCO with a control signal associated with the address;
wherein the digital control circuit further comprises:
a digital counter circuit comprising an input portion coupled to the VCO and an output portion, wherein the VCO is operative to generate a first clock signal and a second clock signal, wherein the second clock signal is an inverted version of the first clock signal, and wherein the first and second clock signals are coupled to the digital counter circuit, wherein the digital counter circuit is operative to count a number of clock cycles received from the VCO, store the count in at least one register, and provide the count to the output portion of the digital counter circuit.
24. The in-body device according to claim 23 , wherein the in-body device is an ingestible device.
25. The in-body device according to claim 23 , wherein the in-body device is an implantable device.
26. The ingestible event marker according to claim 1 , wherein the VCO is operative to generate a digital clock signal in response to activation of the identifier.
27. The ingestible event marker according to claim 1 , wherein the control signal received by the VCO is encoded in a serial bit stream.
28. The ingestible event marker according to claim 1 ,
wherein the digital control circuit further comprises: a multiplexer circuit comprising an input portion and an output portion, the input portion of the multiplexer circuit is coupled to an output portion of the digital counter circuit, wherein the multiplexer circuit is operative to convert the count into an address stored in the multiplexer circuit.
29. The ingestible event marker according to claim 28 , wherein the control signal produced by the multiplexer circuit encodes the address as a serial bit stream, wherein the control signal is provided to the VCO to control the output frequency of the VCO.
30. The ingestible event marker according to claim 29 , wherein the digital control circuit further comprises:
an electrode drive circuit coupled to the multiplexer circuit to broadcast the serial bit stream which constitutes the address stored in the multiplexer circuit.
31. The system according to claim 16 , wherein the VCO is operative to generate a digital clock signal in response to activation of the identifier.
32. The system according to claim 16 , wherein the control signal received by the VCO is encoded in a serial bit stream.
33. The system according to claim 16 ,
wherein the digital control circuit further comprises:
a multiplexer circuit comprising an input portion and an output portion, the input portion of the multiplexer circuit coupled to an output portion of the digital counter circuit, wherein the multiplexer circuit is operative to convert the count into an address stored in the multiplexer circuit.
34. The system according to claim 33 , wherein the control signal produced by the multiplexer circuit encodes the address as a serial bit stream, wherein the control signal is provided to the VCO to control the output frequency of the VCO.
35. The system according to claim 34 , wherein the digital control circuit further comprises:
an electrode drive circuit coupled to the multiplexer circuit to broadcast the serial bit stream which constitutes the address stored in the multiplexer circuit.
36. The kit according to claim 20 , wherein the VCO is operative to generate a digital clock signal in response to activation of the identifier.
37. The kit according to claim 20 , wherein the control signal received by the VCO is encoded in a serial bit stream.
38. The kit according to claim 20 ,
wherein the digital control circuit further comprises:
a multiplexer circuit comprising an input portion and an output portion, the input portion of the multiplexer circuit coupled to an output portion of the digital counter circuit, wherein the multiplexer circuit is operative to convert the count into a corresponding address stored in the multiplexer circuit.
39. The kit according to claim 38 , wherein the control signal produced by the multiplexer circuit encodes the address as a serial bit stream, wherein the control signal is provided to the VCO to control the output frequency of the VCO.
40. The kit according to claim 39 , wherein the digital control circuit further comprises:
an electrode drive circuit coupled to the multiplexer circuit to broadcast the serial bit stream which constitutes the address stored in the multiplexer circuit.