Method and apparatus for a burst operation pressure sensor
Embodiments described herein relate to an implantable device that include an inductor coil, a storage capacitor, active circuitry, and a sensor, but doesn't include an electrochemical cell, and methods for use therewith. During first periods of time, the storage capacitor accumulates and stores energy received via the inductor coil from a non-implanted device. During second periods of time, interleaved with the first periods of time, and during which energy is not received from the non-implanted device, the active circuitry of the implantable device is powered by the energy stored on the storage capacitor and is used to perform at least one of a plurality of predetermined operations of the implantable device, including, e.g., obtaining a sensor measurement from the sensor of the implantable device, transmitting a communication signal including a sensor measurement to the non-implanted device, and/or receiving a communication signal from the non-implanted device.
1. A method for use by an implantable device that includes an inductor coil, a storage capacitor, active circuitry, and a sensor, but does not include an electrochemical cell for powering the active circuitry, the method comprising:
during first periods of time, the implantable device using the storage capacitor to accumulate and store energy received from a non-implantable device via the inductor coil; and
during at least some second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device, the implantable device using the active circuitry of the implantable device, which is powered by the energy stored on the storage capacitor, to determine a sensor measurement from the sensor.
2. The method of claim 1 , further comprising:
the implantable device detecting a transition from an instance of the first period of time to an instance of the second period of time, and in response thereto, the implantable device triggering use of the active circuitry thereof to determine the sensor measurement from the sensor thereof.
3. The method of claim 1 , further comprising:
during at least some of the second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device, converting a said sensor measurement from an analog measurement to a digital measurement and storing the digital measurement in memory of the implantable device.
4. The method of claim 1 , wherein the implantable device includes one or more reference capacitors, and the method further comprises:
using the active circuitry to determine one or more reference capacitance measurements of at least one of the one or more reference capacitors and convert one or more said reference capacitance measurements from analog to digital measurements that are stored in memory and/or transmitted in one or more communication signals from the implantable device to the non-implantable device;
wherein changes over time in the reference capacitance measurements are indicative of drift in the active circuitry; and
wherein one or more of the reference capacitance measurements are used by at least one of the implantable device or the non-implantable device to compensate for the drift in the active circuitry.
5. The method of claim 1 , further comprising:
during at least some of the second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device, converting a said sensor measurement from an analog measurement to a digital measurement and transmitting the digital measurement to the non-implantable device.
6. The method of claim 1 , wherein:
during the first periods of time the inductor coil of the implantable device receives AC power signals from the non-implantable device, and the implantable device converts the AC power signals to DC signals that are used to charge the storage capacitor of the implantable device.
7. The method of claim 1 , wherein the sensor of the implantable device comprises a pressure sensor.
8. The method of claim 7 , wherein the pressure sensor of the implantable device comprises a passive capacitive pressure sensor.
9. An implantable device, comprising:
an inductor coil;
a storage capacitor configured to accumulate and store energy received from a non-implantable device via the inductor coil during first periods of time;
a sensor; and
active circuitry powered by the energy stored on the storage capacitor and including sensor measurement circuitry configured to determine a sensor measurement from the sensor during at least some second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device.
10. The implantable device of claim 9 , wherein:
the active circuitry also includes circuitry configured to detect a transition from an instance of the first period of time to an immediately following instance of the second period of time, and in response thereto, trigger use of the sensor measurement circuitry to determine the sensor measurement from the sensor.
11. The implantable device of claim 10 , wherein the circuitry configured to detect a transition from an instance of the first period of time to an immediately following instance of the second period of time, comprises:
a diode including an anode and a cathode; and
a comparator including a first input terminal, a second input terminal, and an output terminal;
the anode of the diode coupled to a terminal of the inductor coil;
the cathode of the diode coupled to the first input terminal of the comparator; and
the second input terminal of the comparator provided with a reference voltage;
wherein the output terminal of the comparator transitions from a first voltage level to a second voltage level whenever a voltage on the cathode of the diode falls below the reference voltage provided to the second input terminal of the comparator.
12. The implantable device of claim 9 , further comprising:
memory;
wherein the active circuitry is configured to convert a said sensor measurement from an analog measurement to a digital measurement and store the digital measurement in the memory, during one or more of the second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device.
13. The implantable device of claim 9 , wherein:
the active circuitry is configured to convert a said sensor measurement from an analog measurement to a digital measurement and transmit the digital measurement to the non-implantable device, during one or more of the second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device.
14. The implantable device of claim 13 , wherein:
the inductor coil is used during one or more of the second periods of time to transmit one or more of the digital measurements to the non-implantable device.
15. The implantable device of claim 9 , further comprising:
one or more reference capacitors;
wherein the active circuitry is configured to determine one or more reference capacitance measurements of at least one of the one or more reference capacitors and convert at least one of the one or more reference capacitance measurements from analog to digital measurements that are stored in memory and/or transmitted in one or more communication signals from the implantable device to the non-implantable device;
wherein changes over time in the reference capacitance measurements are indicative of drift in the active circuitry; and
wherein the reference capacitance measurements are used by at least one of the implantable device or the non-implantable device to compensate for the drift in the active circuitry.
16. The implantable device of claim 9 , wherein the sensor comprises a pressure sensor.
17. The implantable device of claim 16 , wherein the pressure sensor comprises a passive capacitive pressure sensor.
18. The implantable device of claim 9 , further comprising:
a hermetic housing;
wherein the inductor coil, the storage capacitor, the active circuitry, and the sensor are all within the hermetic housing.
19. A system, comprising:
a non-implantable device; and
an implantable device;
the non-implantable device including
a first inductor coil;
a power supply; and
a driver coupled to the power supply and the inductor coil and configured to drive the inductor coil with an AC signal during first periods of time, and not drive the inductor coil with an AC signal during second periods of time that are distinct from the first periods of time; and
the implantable device including:
a second inductor coil;
a storage capacitor configured to accumulate and store energy received by the implantable device from the non-implantable device via the second inductor coil during the first periods of time;
a sensor; and
active circuitry powered by the energy stored on the storage capacitor and including sensor measurement circuitry configured to determine a sensor measurement from the sensor during one or more of the second periods of time that are distinct from the first periods of time and during which energy is not received by the implantable device from the non-implantable device.
20. The system of claim 19 , wherein:
the active circuitry of the implantable device also includes circuitry configured to detect a transition from an instance of the first period of time to an immediately following instance of the second period of time, and in response thereto, trigger use of the sensor measurement circuitry to determine the sensor measurement from the sensor.
21. The method of claim 1 , wherein the second periods of time are interleaved with the first periods of time.