Ingestible event marker systems
Ingestible event marker systems that include an ingestible event marker (i.e., an IEM) and a personal signal receiver are provided. Embodiments of the IEM include an identifier, which may or may not be present in a physiologically acceptable carrier. The identifier is characterized by being activated upon contact with a target internal physiological site of a body, such as digestive tract internal target site. The personal signal receiver is configured to be associated with a physiological location, e.g., inside of or on the body, and to receive a signal the IEM. During use, the IEM broadcasts a signal which is received by the personal signal receiver.
1. An ingestible event marker comprising:
a battery section including two electrodes configured to supply a battery voltage upon contacting a body fluid by generating a current between the two electrodes using the body fluid as a conductive medium;
an integrated circuit (IC) configured to store an identification code; and
an electric monopole antenna communicatively coupled to the IC;
wherein the IC comprises:
a control logic configured to control an impedance between the two electrodes to alter the current flowing through the body fluid to transmit a coded signal representing the identification code through the electrical monopole antenna as a monophasic electrical signal;
a power supply circuit coupled to the control logic; and
a capacitor coupled to the control logic, the battery section, and the power supply circuit, the capacitor configured to be chargeable by the battery voltage.
2. The ingestible event marker according to claim 1 , wherein:
when a level of charge stored within the capacitor is below a predetermined threshold,
the control logic is configured to generate a recharge signal, and
the power supply circuit further comprises a recharge transistor configured to couple the battery voltage to the capacitor and to recharge the capacitor based upon the recharge signal.
3. The ingestible event marker according to claim 1 , wherein the power supply circuit further comprises a diode to prevent a charge stored in the capacitor to flow back to the electrodes.
4. The ingestible event marker according to claim 3 , wherein the diode is a Schottky diode.
5. The ingestible event marker according to claim 1 , wherein the IC further comprises an oscillator coupled to the capacitor and the control logic, the control logic configured to control the oscillator to generate a clock signal based on the battery voltage.
6. The ingestible event marker according to claim 1 , wherein the IC further comprises a switch coupled to the control logic, the switch configured to change an impedance between the two electrodes.
7. The ingestible event marker according to claim 6 , wherein the switch changes the impedance between the two electrodes based upon the coded signal transmitted by the control logic.
8. The ingestible event marker according to claim 6 , wherein the capacitor is charged when the switch is turned off.
9. The ingestible event marker according to claim 6 , wherein the two electrodes are shorted when the switch is turned on.
10. The ingestible event marker according to claim 1 , wherein the transmission of the identification code includes a cycle pattern of an ON period and an OFF period, wherein the OFF period is longer than the ON period.
11. The ingestible event marker according to claim 10 , wherein the capacitor is configured to be charged by the battery voltage during the OFF period, and wherein the electric monopole antenna does not transmit the coded signal during the OFF period.
12. The ingestible event marker according to claim 1 , wherein the battery section forms a voltaic cell to produce the battery voltage when the electrodes are coupled with the body fluid.
13. The ingestible event marker according to claim 1 , wherein the electric monopole antenna comprises one electrode of the two electrodes.
14. An ingestible event marker comprising:
a battery section including two electrodes configured to supply a battery voltage upon contacting a body fluid by generating a current between the two electrodes using the body fluid as a conductive medium;
an integrated circuit (IC) coupled to the battery section and configured to store an identification code; and
wherein the IC comprises:
a transmission switch transistor coupled to the two electrodes;
a control logic configured to control the transmission switch transistor to control an impedance between the two electrodes to alter the current flowing through the body fluid to transmit a coded signal representing the identification code using binary phase-shift keying (BPSK) modulation via a carrier frequency generated by an oscillator;
a power supply circuit coupled to the control logic; and
a capacitor coupled to the control logic and the power supply circuit, the capacitor configured to be chargeable by the battery voltage.