Ultra-low power memory for embedded devices

Abstract

The implantable device may include a power management unit configured to receive power from an external power source, one or more sensors, and a memory configured to store data detected by the one or more sensors. The memory may include a first binary storage element electrically coupled to the sensor and a main power line coupled to the power management unit, a first binary data memory storage element, and a second binary storage element coupled to a retention power line connected to the power source. The device may include a digital circuit configured to determine that the power management unit is not receiving power from the external power source, detect that a predetermined condition has been met, store data collected by the sensor in the second binary data memory storage element, and disconnect the main power line from the power source.

Description

[Technical Field]

[0001] [CROSS-REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of priority to U.S. Patent Application No. 63 / 417,639, filed October 19, 2022, the entire contents of which are incorporated herein by reference for all purposes.

[0002] [Technical field] The present invention relates to a memory system for an implantable device, and in particular for an implantable device configured to detect physiological signals of a subject. [Background technology]

[0003] Implantable devices for monitoring physiological signals in a subject can collect data that provides a better understanding of health and disease prognosis. For example, an implantable device for monitoring blood glucose can be used to monitor the health of diabetic patients, and an implantable device for monitoring blood oxygen levels can be used to monitor compartment syndrome, cancer, or organ transplants.

[0004] Due to their size, some implantable devices may rely primarily on energy harvested or transferred from a source external to the device to operate. While implantable devices may have the ability to store energy provided by an external energy source, this ability may be quite limited. When the external energy source is removed, the implantable device may need to perform operations and retain a required amount of data without depleting the energy stored on the device. Conventional reprogrammable nonvolatile memory elements (e.g., flash), which retain data when power is lost, require large amounts of energy to program the data. Furthermore, conventional reprogrammable nonvolatile memory elements may be too large for applications that need to retain only small amounts of data. Conventional volatile memory elements (e.g., SRAM) require large amounts of energy to store data and may completely deplete the energy stored in the device when energy is not provided by an external source. Summary of the Invention

[0005] The implantable devices described herein have a storage element (memory element) that can retain small amounts of data using a very small amount of power while the rest of the device is in a low-power "sleep" mode. In some embodiments, the memory element has at least two separate binary data memory storage elements, each of which can be independently coupled to the device's power source. When the device is not receiving energy from an external power source, the primary binary data memory storage element, which can store data collected by the device when sufficient power is available, can be disconnected from the power source to conserve stored energy for an extended period of time. A secondary "retention" binary data memory storage element may remain connected to the power source and may store small amounts of data essential for the continued operation of the device.

[0006] The implantable device provided herein may include an energy storage configured to receive power from an external power source, one or more sensors configured to measure physiological signals, a memory configured to store physiological signal data measured by the one or more sensors, and a digital circuit. The memory may include a first binary data memory storage element electrically coupled to the one or more sensors and a main power line electrically coupled to the energy storage, a second binary data memory storage element electrically coupled to the first binary data memory storage element, and a retention power line electrically coupled to the energy storage. The first binary data memory storage element may include a flip-flop circuit, and the second binary data memory storage element may include a retention latch circuit. The digital circuit may be configured to determine that the power management unit is not receiving power from the external power source, detect that a predetermined condition has been met, store a required portion of the physiological signal data measured by the one or more sensors in the second binary data memory storage element, and disconnect the main power line from the energy storage. The essential portion of the physiological signal data stored in the second binary data memory storage element includes data relating to the most recently performed measurement.

[0007] The main power line may be configured to transfer a first amount of power from the energy storage to the first binary data memory storage element, and the retention power line may be configured to transfer a second amount of power from the energy storage to the second binary data memory storage element. The second amount of power may be less than the first amount of power. In some embodiments, the second amount of power is 100 picowatts or less.

[0008] The one or more sensors can include a pressure sensor. The pressure sensor can be configured to measure intraocular pressure. Additionally or alternatively, the one or more sensors can include one or more electrodes configured to detect electrophysiological pulses, a sensor configured to detect an analyte concentration, a sensor configured to detect pH, a sensor configured to detect temperature, a sensor configured to detect evoked action potentials in the brain, a sensor configured to detect local field potentials in the brain, or a combination thereof.

[0009] The device may be configured to be fully implantable, or may be configured to be implanted into or attached to a tissue or organ, for example, the device may be configured to be implanted within the eye, on or in central nervous tissue, on or in the brain, or on a peripheral nerve (e.g., the splenic nerve).

[0010] The energy storage may be configured to receive power wirelessly from an external power source. For example, the energy storage may be configured to receive power from ultrasound waves generated by the external power source or from radio frequency waves generated by the external power source. Alternatively, the energy storage may be configured to receive power from the external power source via induction or via a capacitive link. The energy storage may also be configured to receive power from vibrations generated by the external power source using a vibration transducer. In some embodiments, the energy storage includes a capacitor, and in some embodiments, the energy storage includes a battery. In some embodiments, detecting that the predetermined condition is met includes determining that a threshold time period has elapsed since the energy storage last received power from the external device. In other embodiments, detecting that the predetermined condition is met includes determining that a total power level of the energy storage has fallen below a threshold power level.

[0011] A method for collecting and storing data using an implantable device is also provided. The implantable device may include an energy storage device configured to receive power from an external power source, one or more sensors configured to measure physiological signals, a memory configured to store physiological signal data measured by the one or more sensors, and a digital circuit. The memory may include a first binary data memory storage element electrically coupled to the one or more sensors, a main power line electrically coupled to the energy storage, a second binary data memory storage element electrically coupled to the first binary data memory storage element, and a retention power line electrically coupled to the energy storage. The first binary data memory storage element may include a flip-flop circuit, and the second binary data memory storage element may include a retention latch circuit. The method for collecting and storing data using an implantable device may include determining that the energy storage is no longer receiving power from the external power source, detecting that a predetermined condition has been met, storing a required portion of the physiological signal data measured by the one or more sensors in the second binary data memory storage element, and disconnecting the main power line from the energy storage. A substantial portion of the physiological signal data stored in the second binary data memory storage element may include data relating to measurements that were most recently performed.

[0012] The main power line may be configured to transfer a first amount of power from the energy storage to the first binary data memory storage element, and the retention power line may be configured to transfer a second amount of power from the energy storage to the second binary data memory storage element. The second amount of power may be less than the first amount of power. In some embodiments, the second amount of power is 100 picowatts or less.

[0013] The one or more sensors can include a pressure sensor. The pressure sensor can be configured to measure intraocular pressure. Additionally or alternatively, the one or more sensors can include one or more electrodes configured to detect electrophysiological pulses, a sensor configured to detect an analyte concentration, a sensor configured to detect pH, a sensor configured to detect temperature, a sensor configured to detect evoked action potentials in the brain, a sensor configured to detect local field potentials in the brain, or a combination thereof.

[0014] The device may be configured to be fully implantable, or may be configured to be implanted into or attached to a tissue or organ, for example, the device may be configured to be implanted within the eye, on or in central nervous tissue, on or in the brain, or on a peripheral nerve (e.g., the splenic nerve).

[0015] The energy storage may be configured to receive power wirelessly from an external power source. For example, the energy storage may be configured to receive power from ultrasound generated by the external power source or from radio frequency generated by the external power source. Alternatively, the energy storage may be configured to receive power from the external power source via induction or via a capacitive link. The energy storage may also be configured to receive power from vibrations generated by the external power source using a vibration transducer. In some embodiments, the energy storage includes a capacitor, and in some embodiments, the energy storage includes a battery. In some embodiments, detecting that the predetermined condition is met includes determining that a threshold time period has elapsed since the energy storage last received power from the external device. In other embodiments, detecting that the predetermined condition is met includes determining that a total power level of the energy storage has fallen below a threshold power level.

[0016] A non-transitory computer-readable storage medium including instructions for collecting and storing data in an implantable device is also provided. The implantable device may include an energy storage configured to receive power from an external power source, one or more sensors configured to measure physiological signals, and a memory configured to store physiological signal data measured by the one or more sensors. The memory may include a first binary data memory storage element electrically coupled to the one or more sensors, a main power line electrically coupled to the energy storage, a second binary data memory storage element electrically coupled to the first binary data memory storage element, and a retention power line electrically coupled to the energy storage. The first binary data memory storage element may include a flip-flop circuit, and the second binary data memory storage element may include a retention latch circuit. When executed by the digital circuitry of the electronic device, the instructions contained in the non-transitory computer-readable storage medium provided herein can cause the electronic device to determine that the energy storage is not receiving power from an external power source, detect that a predetermined condition has been met, store an essential portion of the physiological signal data measured by the one or more sensors in a second binary data memory storage element, and disconnect the main power line from the energy storage. A substantial portion of the data stored in the second binary data memory storage element can include data related to the most recently performed measurement.

[0017] The main power line may be configured to transfer a first amount of power from the energy storage to the first binary data memory storage element, and the retention power line may be configured to transfer a second amount of power from the energy storage to the second binary data memory storage element. The second amount of power may be less than the first amount of power. In some embodiments, the second amount of power is 100 picowatts or less.

[0018] The one or more sensors can include a pressure sensor. The pressure sensor can be configured to measure intraocular pressure. Additionally or alternatively, the one or more sensors can include one or more electrodes configured to detect electrophysiological pulses, a sensor configured to detect an analyte concentration, a sensor configured to detect pH, a sensor configured to detect temperature, a sensor configured to detect evoked action potentials in the brain, a sensor configured to detect local field potentials in the brain, or a combination thereof.

[0019] The device may be configured to be fully implantable, or may be configured to be implanted into or attached to a tissue or organ, for example, the device may be configured to be implanted within the eye, on or in central nervous tissue, on or in the brain, or on a peripheral nerve (e.g., the splenic nerve).

[0020] The energy storage may be configured to receive power wirelessly from an external power source. For example, the energy storage may be configured to receive power from ultrasound generated by the external power source or from radio frequency generated by the external power source. Alternatively, the energy storage may be configured to receive power from the external power source via induction or via a capacitive link. The energy storage may also be configured to receive power from vibrations generated by the external power source using a vibration transducer. In some embodiments, the energy storage includes a capacitor, and in some embodiments, the energy storage includes a battery. In some embodiments, detecting that the predetermined condition is met includes determining that a threshold time period has elapsed since the energy storage last received power from the external device. In other embodiments, detecting that the predetermined condition is met includes determining that a total power level of the energy storage has fallen below a threshold power level. [Brief explanation of the drawings]

[0021] Various aspects of the disclosed method and system are set forth with particularity in the appended claims. A better understanding of the features and advantages of the disclosed method and system can be obtained by reference to the detailed description of exemplary embodiments and the accompanying drawings.

[0022] [Figure 1] 1 shows a schematic diagram of an exemplary system including an implantable device with ultra-low power memory, according to some embodiments. The exemplary system is configured to measure intraocular pressure.

[0023] [Figure 2] 1 illustrates an exemplary implantable device with ultra-low power memory, according to some embodiments of the present disclosure.

[0024] [Figure 3] 1 illustrates an exemplary memory for an implantable device according to some embodiments of the present disclosure.

[0025] [Figure 4A] 1 illustrates an exemplary interrogator for providing energy to and communicating with an implantable device, according to some embodiments.

[0026] [Figure 4B] 1 shows an exemplary schematic diagram of an exemplary interrogator for providing energy to and communicating with an intraocular implantable device for measuring intraocular pressure, according to some embodiments.

[0027] [Figure 5] 1 illustrates an exemplary interrogator in communication with an exemplary implantable device, according to some embodiments.

[0028] [Figure 6A] 1 illustrates an exemplary method for storing data using an implantable device, according to some embodiments of the present disclosure.

[0029] [Figure 6B] 1 illustrates an example method for detecting that an example predetermined condition that may be associated with a power level in an implantable device has been met, according to some embodiments of the present disclosure.

[0030] [Figure 6C] 1 illustrates an example method for detecting that an example predetermined condition that may be associated with a power level in an implantable device has been met, according to some embodiments of the present disclosure.

[0031] [Figure 7] 1 illustrates an exemplary method for retrieving data from an implantable device that was recently in a low-power "sleep" mode.

[0032] [Figure 8] An exemplary method for using an intraocular implant to measure intraocular pressure, storing intraocular pressure data when the implant is in a low-power "sleep" mode, and transmitting the intraocular pressure data to an interrogator is shown.

[0033] [Figure 9A] 1 illustrates an exemplary implementation of a first binary data memory storage element and a second binary data memory storage element of a memory for an implantable device.

[0034] [Figure 9B] 9B illustrates an exemplary implementation of the retention D flip-flop circuit shown in FIG. 9A.

[0035] [Figure 9C] 9C illustrates an exemplary implementation of the first type of inverter shown in FIG. 9B.

[0036] [Figure 9D] 9C illustrates an exemplary implementation of the second type of inverter shown in FIG. 9B.

[0037] [Figure 9E] 9C illustrates an exemplary implementation of the third type of inverter shown in FIG. 9B.

[0038] [Figure 10] 9B illustrates an exemplary method for storing data using the memory element shown in FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0039] The implantable devices provided herein can be configured to be implanted in a subject to monitor one or more physiological signals. In some embodiments, the physiological signals include pH, analyte level, electrophysiological pulses, temperature, applied pressure, electrical potential, or a combination thereof. The implantable device can be configured to receive energy from an energy source separate from (i.e., external to) the device. A device including an energy source may be a non-implantable device. The energy received from the external power source can be used to power the device. The implantable device can include a power management unit including an energy storage configured to store a portion of the energy received from the external power source. When the external power source stops supplying energy to the implantable device, the implantable device can begin drawing energy stored in the energy storage.

[0040] The implantable devices provided herein may include memory configured to store small amounts of data essential for the continued operation of the device when energy is not provided by an external power source. The memory may require a very small amount of power to store the essential data and may be configured to retain the data while other components of the device are disconnected from the power management unit.

[0041] A memory can comprise multiple binary data memory storage elements. As used herein, a "binary data memory storage element" may refer to any device, apparatus, or system configured to store information encoded as binary numbers ("bits"). One or more bits in a binary data memory storage element may be physically implemented using one or more physical systems that can exist in either of two physically distinct states. In some embodiments, the physical system used to store bits of data in a binary data memory storage element may be a flip-flop circuit, an electrical switch, a circuit configured to allow two distinct current levels, a circuit configured to allow two distinct voltage levels, or a system having two distinct magnetization directions.

[0042] In some embodiments, the implantable device's memory may comprise two separate binary data memory storage elements, each of which may be independently coupled to the implantable device's power management unit. The first binary data memory storage element may comprise one or more flip-flop circuits and may be configured to program and store data received from the device's physiological signal sensors when the device has a sufficiently high amount of available power. The second binary data memory storage element may comprise one or more retention latch circuits and may be configured to receive and store a required portion of the data stored in the first binary data memory storage element when one or more conditions are met. In some embodiments, the conditions may be related to the total amount of power remaining in the device's energy storage or the amount or type of data collected. Once the required data portion is transmitted to the second binary data memory storage element, the implantable device may be configured to disconnect one or more elements, including the first binary data memory storage element, from the energy storage. The second binary data memory storage element may remain coupled to the energy storage, thereby ensuring that the required data portion is retained while the remainder of the implantable device is in a low-power "sleep" mode.

[0043] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0044] References herein to "about" a value or parameter include (and describe) a variation that is directed to the value or parameter itself. For example, a description that refers to "about X" includes a description of "X."

[0045] A "binary data memory storage element" may refer to any device, apparatus, or system configured to store information encoded as binary numbers ("bits"). One or more bits in a binary data memory storage element may be physically implemented using one or more physical systems that can exist in either of two physically distinct states. In some embodiments, the physical system used to store bits of data in a binary data memory storage element may be a flip-flop circuit, an electrical switch, a circuit configured to allow two distinct current levels, a circuit configured to allow two distinct voltage levels, or a system with two distinct magnetization directions.

[0046] When a range of values ​​is provided, it is understood that each intervening value between the upper and lower limit of that range, and any other stated or intervening value in that stated range, is encompassed within the scope of the disclosure. When a stated range includes an upper or lower limit, ranges excluding either of those included limits are also included in the disclosure.

[0047] It should be understood that one, some, or all of the features of the various embodiments described herein may be combined to form other embodiments of the present invention. The section headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

[0048] The features and preferences described above in connection with an "embodiment" are separate preferences and not limited to that particular embodiment; they can be freely combined with features from other embodiments where technically feasible to form preferred combinations of features. The description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the general principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein. Moreover, section headings are provided for organizational purposes and should not be considered limiting. Finally, the entire disclosures of the patents and publications referred to in this application are incorporated herein by reference for all purposes. To the extent any reference incorporated by reference conflicts with the present disclosure, the present disclosure shall control.

[0049] Implantable Devices An implantable device for sensing physiological signals (e.g., pH, analyte concentration, applied pressure, strain, or temperature) in a subject (e.g., a human or animal) can be powered through the harvesting or transfer of energy from an energy source external to the device. The implantable device may be capable of receiving energy from an external energy source only when the external energy source is within a certain range of the implantable device. Furthermore, the implantable device may only be capable of storing a small amount of energy transferred from the external energy source; for example, if the external energy source is moved out of range of the implantable device, the implantable device may have very low stored available power.

[0050] In some implementations, an implantable device may need to perform one or more operations (e.g., measuring physiological signals) and retain data associated with the operations after the external energy source is removed. The implantable device may need to operate and retain data without depleting the energy storage on the device. The implantable devices described herein include memory configured to store the requisite amount of data while consuming very little energy from the device's energy storage.

[0051] An exemplary implementation in which an implantable device may need to perform measurements of physiological signals and retain data associated with the measurements after an external energy source is removed is an intraocular implantable device for measuring intraocular pressure. FIG. 1 shows a schematic diagram of an exemplary system for measuring intraocular pressure. Specifically, FIG. 1 shows a system 100 comprising an implantable device 104 and an external device 112. The implantable device 104 may be configured to be implanted in a subject's eye and may comprise a pressure sensor configured to measure intraocular pressure (IOP) of the eye. The external device 112 may be configured to provide energy to and wirelessly communicate with the implantable device 104.

[0052] In some embodiments, the external device 112 may need to be brought into contact with a proximal location of the patient's eye to provide energy to the implantable device 104. When the external device 112 is brought into contact with a proximal location of the patient's eye, the external device 112 may apply pressure to the patient's eye. This added pressure from the presence of the external device 112 may change the IOP of the eye. Therefore, to ensure that the IOP measurement is not affected by the presence of the external device 112, the implantable device 104 may be configured to measure the IOP only after the external device 112 is removed from contact with the proximal location of the patient's eye.

[0053] When the external device 112 is removed from a position proximate the patient's eye, the external device 112 may stop providing energy to the implantable device 104. Accordingly, the implantable device 104 may include a small energy storage device (e.g., a small capacitor) configured to store energy transmitted from the external device 112 so that the implantable device 104 can continue to function for a short period of time after removal of the external device 112. The energy storage device on the implantable device 104 may provide the implantable device 104 with sufficient power to measure the IOP of the subject's eye and store information related to the IOP measurement in a memory element of the implantable device 104.

[0054] In order for the IOP information to be analyzed by a user, the IOP information may need to be transferred from the implantable device 104. The implantable device 104 may be configured to wirelessly transmit the IOP information to the external device 112. However, the external device 112 may need to be repositioned to a position proximal to the patient's eye for the wireless transfer of the IOP information to occur. Conventional memory elements can quickly deplete the energy storage of the implantable device 104; for example, if the IOP information is not transferred to the external device 112 within a short time window, the energy stored on the implantable device 104 may be depleted and the IOP information may be lost. Therefore, to prevent the IOP information from being lost, the implantable device 104 may require a memory element that can retain the IOP information for an extended period of time while consuming a very small amount of energy from the energy storage of the implantable device 104.

[0055] 2 illustrates an exemplary implantable device with ultra-low power memory in accordance with some embodiments of the present disclosure. Specifically, FIG. 2 illustrates implantable device 200 with a power management unit 202 configured to store and distribute energy to components of implantable device 200, a digital core (also referred to as a “digital circuit”) 204 configured to control one or more components of implantable device 200, a modulation circuit 206 configured to encode information in an electric current, a transmitter 208 configured to wirelessly transfer and receive energy from an external device 224, one or more sensors 210 configured to detect one or more physiological signals, and a memory 212 configured to store data received from the one or more sensors 210.

[0056] Implantable device 200 may be configured to be fully implantable in a subject (e.g., a human or animal body part). This may allow for careful monitoring of specific physiological signals in the subject. In some embodiments, implantable device 200 may be configured to be implanted within or attached to tissue. For example, implantable device 200 may be configured to be implanted within or on central nervous tissue, such as the brain. In some embodiments, implantable device 200 may be configured to be implanted within or attached to an organ. For example, implantable device 200 may be configured to be implanted in the eye. In some embodiments, implantable device 200 may be configured to be implanted in a peripheral nerve (e.g., the splenic nerve) or a neurovascular bundle.

[0057] In some embodiments, the overall size of implantable device 200 may be small to allow the implantable device to be more easily implanted in a subject. In some embodiments, implantable device 200 may have a longest dimension of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm or more. In some embodiments, implantable device 100 may have a longest dimension of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm or less. In some embodiments, implantable device 200 may have a longest dimension of about 0.5-1.5 mm, about 1.5-2.5 mm, about 2.5-3.5 mm, about 3.5-4.5 mm, or about 4.5-5 mm. In some embodiments, implantable device 200 may have a total volume of 0.5 mm or less. 3 , 1mm 3 , 1.5mm 3 , 2mm 3 , 2.5mm 3 , 3mm 3 , 3.5mm 3 , 4mm 3 , 4.5mm 3 or 5mm 3 In some embodiments, the implantable device 200 may have a total volume of 0.5 mm 3 , 1mm 3 , 1.5mm 3 , 2mm 3 , 2.5mm 3 , 3mm 3 , 3.5mm 3 , 4mm 3 , 4.5mm 3 or 5mm 3 In some embodiments, implantable device 200 may have a total volume of about 0.5-1.5 mm 3 , about 1.5~2.5mm 3 , about 2.5~3.5mm 3 , about 3.5~4.5mm 3 , or about 4.5 to 5 mm 3 It may be between.

[0058] 2, implantable device 200 may be configured to couple to an external device 224. "External," as used herein, refers to any area outside of (i.e., separate from) implantable device 200. In some embodiments, external device 224 may be external to the subject in which implantable device 100 is implanted. In some embodiments, external device 224 may be implanted in the subject along with implantable device 200, but may be separate from (i.e., external to) implantable device 200. External device 224 may be configured to wirelessly transmit signals to and receive signals from one or more components of implantable device 200.

[0059] In some embodiments, external device 224 may include communications circuitry 226, transmitter 228, and power management circuitry 230. Transmitter 228 may be configured to wirelessly transmit energy to implantable device 200. In some embodiments, transmitter 228. Energy transmitted by transmitter 228 to implantable device 200 may include any form of energy originating from outside implantable device 200. In some embodiments, transmitter 228 may be configured to transmit energy to implantable device 200 in the form of ultrasonic or electromagnetic waves, such as radio frequency waves. In some embodiments, transmitter 228 may be configured to transmit energy to implantable device 200 via induction or via a capacitive link.

[0060] The transmitter 208 on the implantable device 200 may be configured to receive energy transmitted to the implantable device 200 by the transmitter 228 on the external device 224. The transmitter 208 may be configured to convert the energy received from the transmitter 228 into an electric current. The electric current generated by the transmitter 208 may then be transmitted to the power management unit 202.

[0061] In some embodiments, transmitter 228 may transmit energy in the form of ultrasound waves to implantable device 200. Transmitter 208 may comprise one or more ultrasound transducers configured to convert ultrasound waves received from transmitter 228 into electrical current. The one or more ultrasound transducers may comprise bulk piezoelectric transducers, piezoelectric micromachined ultrasound transducers (PMUTs), or capacitive micromachined ultrasound transducers (CMUTs).

[0062] In some embodiments, transmitter 228 can transmit energy in the form of electromagnetic waves to implantable device 200. Transmitter 208 may include one or more antennas or one or more coils configured to convert electromagnetic waves (e.g., radio frequency waves) received from transmitter 228 into electrical current.

[0063] In some embodiments, transmitter 228 can transmit energy to implantable device 200 in the form of vibrational energy. Transmitter 208 can include one or more vibration transducers configured to convert vibrations received from transmitter 228 into electrical current. In some embodiments, transmitter 208 can include one or more piezoelectric crystals configured to convert vibrations received from transmitter 228 into electrical current.

[0064] In some embodiments, the transmitter 228 can transmit energy to the implantable device 200 via induction. The transmitter 208 can include a wire coil. The transmitter 228 may also include a wire coil. The power management circuit 230 can be configured to generate an alternating current through the wire coil. The alternating current in the external wire coil can generate a magnetic field. The generated magnetic field can induce an alternating current in the coil of the transmitter 280.

[0065] In some embodiments, transmitter 228 can transmit energy to implantable device 200 via a capacitive link. Transmitters 208 and 228 can each include electrodes such that when external device 224 is brought within a certain distance of implantable device 200, an electrode in transmitter 208 and an electrode in transmitter 228 form a capacitor. An oscillating voltage can be applied to the external electrodes by power management circuitry 230. The oscillating voltage can induce an oscillating electric field between the electrodes of transmitter 228 and the electrodes of transmitter 208. This oscillating electric field can induce an oscillating voltage on the electrodes of transmitter 208, thereby generating an alternating current that can be transmitted to power management unit 202.

[0066] Power management unit 202 may include an AC / DC rectifier 218, an energy storage 220, and a power management logic circuit 222. AC / DC rectifier 218 and energy storage 220 may be controlled by power management logic 222. Specifically, power management logic 222 may monitor signals received by AC / DC rectifier 218 to ensure implantable device 200 is operating at maximum efficiency. Furthermore, power management logic 222 may be configured to boost, step down, and / or adjust the voltage of AC / DC rectifier 218 to safely charge energy storage 220. Power management logic 222 may monitor the current, voltage, and / or energy of energy storage 220. In some embodiments, power management logic 222 may be configured to send a signal including information regarding the energy level in energy storage 220 to digital core 204.

[0067] As mentioned above, the current generated by the transmitter 208 may be an AC current. This generated AC current may be transmitted from the transmitter 208 to the AC / DC rectifier 218, which may convert it to a DC current. This DC current may then be transmitted to the energy storage 220. The energy storage 220 may include one or more capacitors configured to store the energy carried by the current transmitted by the transmitter 208.

[0068] As described above, the implantable device 200 may include one or more sensors 210 configured to sense one or more physiological signals. In some embodiments, the one or more sensors 210 may include a pressure sensor configured to measure pressure within a subject (e.g., intraocular pressure within a subject's eye). In some embodiments, the one or more sensors 210 may include one or more electrodes configured to detect electrophysiological pulses (e.g., electrophysiological pulses transmitted by nerves, such as peripheral nerves). In some embodiments, the one or more sensors 210 may include one or more sensors configured to detect the concentration of an analyte (e.g., glucose or oxygen). In some embodiments, the one or more sensors 210 may include a temperature sensor configured to measure temperature. In some embodiments, the one or more sensors 210 may include one or more sensors configured to measure pH. In some embodiments, the one or more sensors 210 may include one or more sensors configured to measure strain. In some embodiments, the one or more sensors 210 may include one or more sensors configured to measure evoked action potentials in the brain. In some embodiments, the one or more sensors 210 may include one or more sensors configured to measure local field potentials in the brain.

[0069] In some embodiments, measurements of physiological signals may be affected if measurements are made while the external device 224 is providing energy to the implantable device 200. The transmitter 228 in the external device 224 may need to be brought into close proximity to the transmitter 208 in the implantable device 200 to transfer energy to the transmitter 208. In some embodiments, this may require the external device 224 to be in direct contact with the subject. The proximity or contact of the external device 224 and / or the energy transmitted by the external device 224 may affect the physiological conditions that the one or more sensors 210 are configured to measure.

[0070] To prevent errors in the physiological signal measurements, one or more sensors 210 may be configured to measure one or more physiological signals when external device 224 is not providing energy to implantable device 200. When a user desires to make a physiological signal measurement, external device 224 may transfer energy to implantable device 200 until energy storage 220 reaches maximum capacity. External device 224 may then be caused to stop transferring energy to implantable device 200 (e.g., by the user removing external device 224 from a location proximal to the body part in which implantable device 200 is implanted).

[0071] In some embodiments, the digital core 204 on the implantable device 200 may be configured to monitor the amount of energy contained in the energy storage 220. When the energy storage 220 reaches maximum capacity, the digital core 204 may cause the modulation circuitry 206 to encode, in a current, an instruction configured to cause the external device 224 to stop transferring energy to the implantable device 200. The information-encoded current may be transmitted from the modulation circuitry 206 to the transmitter 208. The transmitter 208 may convert the information-encoded current into an energy signal (e.g., ultrasound or radio waves). This energy signal may be transmitted to the transmitter 228 of the external device 224, which may convert the energy signal back into an information-encoded current. This information-encoded current may be transmitted to the communication circuitry 226, which may extract the instruction encoded in the current and transmit a signal to the user, thereby causing the user to cause the external device 224 to stop transferring energy to the implantable device 200.

[0072] After energy storage 220 is charged (e.g., reaches full capacity or exceeds some capacity threshold) and external device 224 stops transferring energy to implantable device 200, digital core 204 may be configured to cause one or more sensors 210 to measure one or more physiological signals. Because energy is no longer transferred from external device 224 to implantable device 200, the one or more sensors may draw power from energy storage 220 while measuring the one or more physiological signals. In some embodiments, one or more sensors 210 may be electrically coupled to energy storage unit 220 via main power lines 232. Power management logic 222 may be configured to control the flow of energy to one or more sensors 210 via main power lines 232.

[0073] In some embodiments, after a physiological signal is measured by a sensor of one or more sensors 210, digital core 204 can cause the sensor to write the physiological signal data to memory 212 for storage. In some embodiments, after a physiological signal is measured by a sensor of one or more sensors 210, digital core 204 can cause the sensor to write the physiological signal data to memory 212 for storage. Memory 212 can be configured to store the physiological signal data until the data can be retrieved from implantable device 200 by external device 224.

[0074] In some embodiments, memory 212 may comprise a first binary data memory storage element 214 configured to store one or more bits of data and a second binary data memory storage element 216 configured to store one or more bits of data. The first binary data memory storage element 214 may be electrically coupled to one or more sensors 210 and to the second binary data memory storage element 216. In some embodiments, digital core 204 may include N copies of memory 212, where N is an integer greater than or equal to 1.

[0075] The first binary data memory storage element 214 and the second binary data memory storage element 216 may be electrically coupled to an energy storage 220 of the power management unit 202. In some embodiments, the first binary data memory storage element 214 may be electrically coupled to the energy storage 220 via a main power line 232, for example, via the same power line that provides energy to the one or more sensors 210. The second binary data memory storage element 216 may be electrically coupled to the energy storage 220 via a separate retention power line 234.

[0076] In some embodiments, implantable device 200 may include a clock 236 configured to generate an oscillating signal. Clock 236 may be an oscillator (e.g., a quartz crystal). Power management logic 222 may be configured to control the signal generated by clock 236. Digital core 204 may be electrically coupled to clock 236 and may be configured to send a signal received from clock 236 to first binary data memory storage element 214 or second binary data memory storage element 216 to control where and when data is stored in memory 212.

[0077] When one or more of the sensors 210 measure a physiological signal, the digital core 204 may cause the sensor to write data related to the measured physiological signal to the first binary data memory storage element 214. The one or more sensors 210 and the first binary data memory storage element 214 may use energy from the energy storage 220 as they operate. The measurement of the physiological signal and the storage of the physiological signal data in the first binary data memory storage element 214 may proceed until the digital core 204 detects that the amount of energy remaining in the energy storage 220 has fallen below a predetermined threshold level. When the digital core 204 detects that the energy remaining in the energy storage 220 has fallen below a predetermined threshold level, the digital core 204 may be configured to cause a required portion of the data stored in the first binary data memory storage element 214 to be transferred to the second binary data memory storage element 216.

[0078] Just as external device 224 may need to be positioned proximate to the body part in which implantable device 200 is implanted to transfer energy to implantable device 200, external device 224 may need to be positioned proximate to the body part in which implantable device 200 is placed to retrieve physiological signal data stored on implantable device 200. If digital core 204 detects that the amount of energy remaining in energy storage 220 falls below a predetermined threshold level and external device 224 has not yet been relocated to an appropriate location, digital core 204 may be configured to cause implantable device 200 to enter a low-power “sleep” mode. As described below, this low-power “sleep” mode may allow essential portions of the information stored in memory 212 to be retained until it can be retrieved by external device 224 without depleting the energy remaining in energy storage 220.

[0079] In some embodiments, a required portion of the data may be data collected by one or more sensors 210. In some embodiments, a required portion of the data may include status information. In some embodiments, the status information may comprise one or more flags or indicators that indicate that sensor data has been captured or that the sensor data is valid.

[0080] The essential data transferred to the second binary data memory storage element 216 may be data associated with a physiological signal measurement made at a point in time (e.g., the most recent measurement). The power management logic 222 may then be configured to disconnect the main power line 232 from the energy storage 220. With the main power line 232 disconnected, the one or more sensors 210 and the first binary data memory storage element 214 no longer draw energy from the energy storage 220. The second binary data memory storage element 216, coupled to the energy storage 220 via the retention power line 234, may be the only component of the implantable device 200 that continues to draw power from the energy storage 220. In some embodiments, the second binary data memory storage element 216 may be configured to retain the essential data while consuming a very small amount of power from the energy storage 220. At this point, the implantable device 200 enters a low-power “sleep” mode.

[0081] At some point after implantable device 200 enters the low-power “sleep” mode, the user may decide to retrieve the data stored in implantable device 200. External device 224 may be repositioned to a location proximal to the patient's body part. To ensure that implantable device 200 has sufficient energy to transmit the stored data to external device 224, external device 224 may be configured to transmit energy to implantable device 200 using transmitter 228. Transmitter 208 may receive the energy transmitted by transmitter 228 and convert the energy into an electric current. This electric current may be transferred to energy storage 220, thereby increasing the amount of energy contained in energy storage 220. When digital core 204 detects that the amount of energy contained in energy storage 220 exceeds a predetermined threshold level, power management circuit 222 may be configured to “wake up” implantable device 200 by reconnecting main power line 232 to energy storage 220.

[0082] After implantable device 200 has “rebooted,” digital core 204 may be configured to cause external device 224 to send a signal instructing external device 224 to stop transmitting energy to implantable device 200. While external device 224 remains in a position proximate to the patient's body part but is not transmitting energy to implantable device 200, digital core 204 may be configured to cause modulation circuit 206 to modulate the current received from power management unit 202 to encode the required data stored in second binary data memory storage element 216 with the current. In some embodiments, digital core 204 may be configured to cause modulation circuit 206 to encode the required data stored in second binary data memory storage element 216 only if the required data includes status information indicating that sensor data collected by sensor 210 before device 200 entered the low-power “sleep” mode is valid. Modulation circuit 206 may transmit the data-encoding current to transmitter 208. The transmitter 208 can convert the data-encoded current into an energy signal (e.g., ultrasound or radio waves) and transmit the energy signal to the external device 224. The transmitter 228 of the external device 224 can receive the energy signal and convert it back into a data-encoded current. This data-encoded current can be transmitted to the communications circuitry 226 for further processing.

[0083] Ultra-Low Power Memory An implantable device for sensing physiological signals (e.g., implantable device 100 shown in FIG. 1) may include a power management unit including an energy receiver configured to receive energy from a power source external to the device. The power management unit may include energy storage (e.g., one or more capacitors) capable of storing small amounts of power. When an external power source is not providing energy to the power management unit, the implantable device may have a very low level of available power from which it can draw. In some embodiments, for example, the overall size of the implantable device may be limited to allow the device to be implanted in a small area of ​​the body (e.g., the eye). The energy storage capacity of the implantable device may be proportional to the size of the device. The capacitance of a capacitor, for example, is directly proportional to the size of the capacitor. Limiting the size of the implantable device limits the size of the device's energy storage, and consequently, the energy storage capacity of the device.

[0084] After the power management unit stops receiving energy from the external power source, the implantable device may need to retain data for an extended period of time without depleting the energy stored in the power source. Thus, the implantable device may include a memory element (e.g., memory 212 shown in FIG. 2) configured to retain a small amount of data using very little energy while the rest of the device is in a low-power "sleep" mode.

[0085] In some embodiments, a memory element may comprise a plurality of binary data memory storage elements. A binary data memory storage element may be any device, apparatus, or system configured to store information encoded as binary digits (“bits”). One or more bits in a binary data memory storage element may be physically implemented using one or more physical systems that can exist in one of two physically distinct states. In some embodiments, the physical system used to store bits of data in a binary data memory storage element may be a flip-flop circuit, an electrical switch, a circuit configured to allow two distinct current levels, a circuit configured to allow two distinct voltage levels, or a system having two distinct magnetization directions.

[0086] In some embodiments, one or more of the binary data memory storage elements in a memory element can be or comprise flip-flop and / or latch circuits. For example, in some embodiments, a memory element for an implantable device can comprise a retention cell or a retention flip-flop circuit. The retention cell in a memory element for an implantable device can be any retention cell readily available in a standard library cell. In such embodiments, the first binary data memory storage element can comprise a conventional flip-flop circuit, while the second binary data memory storage element can comprise a retention latch circuit.

[0087] 3 illustrates an exemplary memory element for an implantable device according to some embodiments of the present disclosure. Specifically, FIG. 3 illustrates memory 300 comprising a first binary data memory storage element 302 and a second binary data memory storage element 304. In some embodiments, memory 300 may be memory for an implantable device for sensing one or more physiological signals, such as implantable device 200 illustrated in FIG. 2.

[0088] The memory 300 may be electrically coupled to and configured to receive energy from an energy storage on the implantable device. The energy storage may include one or more features of the energy storage 220 of the implantable device 200 shown in FIG. 2. In some embodiments, the first binary data memory storage element 302 and the second binary data memory storage element 304 may be independently electrically coupled to the energy storage via separate power lines.

[0089] The first binary data memory storage element 302 may be electrically coupled to the energy storage via a main power line (e.g., main power line 232). The second binary data memory storage element 304 may be electrically coupled to the energy storage via a separate retention power line (e.g., retention power line 234). The main power line may be configured to transmit a first amount of power from the energy storage to the first binary data memory storage element 302. The retention power line may be configured to transmit a second amount of power from the energy storage to the second binary data memory storage element 304. In some embodiments, the first amount of power transmitted by the main power line may be greater than or equal to the second amount of power transmitted by the retention power line. In some embodiments, the second amount of power may be greater than or equal to 10, 50, 100, 500, 1000, or 10 4 It may be less than a picowatt.

[0090] In some embodiments, the implantable device may include a digital core (i.e., digital circuitry) configured to control power output from the energy storage. In particular, the digital core may be configured to disconnect the main power line from the energy storage whenever the digital core detects that one or more conditions are met. In some embodiments, the one or more conditions may be associated with the amount of energy contained in the energy storage at a given time. When the digital core disconnects the main power line from the energy storage, the implantable device may enter a low-power “sleep” mode, and the first binary data memory storage element 302 (along with any other elements of the implantable device coupled to the energy storage via the main power line) does not draw power from the energy storage. Meanwhile, the retention power line may remain connected to the power management unit 210 via the retention power line 214 at all times, thereby ensuring that the second binary data memory storage element 304 receives a constant energy supply.

[0091] The memory 300 may be configured to store data received from one or more sensors of the implantable device, which may be configured to sense one or more physiological signals (see, for example, one or more sensors 210 shown in FIG. 2).

[0092] In some embodiments, the first binary data memory storage element 302 may be configured to receive and store data transmitted from one or more sensors. In some embodiments, the one or more sensors may be electrically coupled to the implantable device's energy storage via a main power line. Thus, the sensors may transmit data to the first binary data memory storage element 302 for storage only when the main power line is connected to the energy storage, i.e., when the implantable device is "awake."

[0093] The first binary data memory storage element 302 may be or may comprise one or more flip-flop circuits 306. Each flip-flop circuit 306 may have two stable states. The two stable states of each flip-flop circuit 306 may be configured to store binary data. In some embodiments, the first binary data memory storage element 302 may be configured to store one or more bits of data received from one or more sensors by changing the state of the one or more flip-flop circuits 306. In some embodiments, the first binary data memory storage element 302 may be configured to store an amount of data that is equal to or greater than the amount of data that the second binary data memory storage element 304 can store.

[0094] In some embodiments, flip-flop circuit 306 may comprise one or more SR (“Set-Reset”) flip-flops, one or more D (“Data” or “Delay”) flip-flops, one or more T (“Toggle”) flip-flops, and one or more JK flip-flops. Flip-flop circuit 306 may be implemented using one or more pairs of cross-coupled inverting elements. In some embodiments, flip-flop circuit 306 may be implemented using one or more transistors, one or more inverters, and / or one or more logic gates.

[0095] In some embodiments, when the digital core (i.e., digital circuitry) of the implantable device detects one or more conditions indicating that the implantable device should be caused to enter a low-power “sleep” mode, the digital core may be configured to cause memory 300 to transfer a required portion of the data stored in first binary data memory storage element 302 to second binary data memory storage element 304. In some embodiments, the required portion of the data transferred from first binary data memory storage element 302 to second binary data memory storage element 304 may include data related to measurements performed by a sensor at a particular time, such as data related to a measurement most recently performed.

[0096] The second binary data memory storage element 304 may include one or more retention latch circuits 308. Each retention latch circuit 308 may have two stable states. The two stable states of each retention latch circuit 308 may be configured to store binary data. In some embodiments, the second binary data memory storage element 304 may be configured to store one or more bits of the required data portion received from the first binary data memory storage element 302 by changing the state of one or more retention latch circuits 308. The second binary data memory storage element 304 may include fewer retention latch circuits 308 than the number of flip-flop circuits 306 included in the first binary data memory storage element 302. Thus, the second binary data memory storage element 304 may have a smaller storage capacity than the first binary data memory storage element 302. In some embodiments, the second binary data memory storage element 304 may be capable of storing about 1-10, about 10-50, about 10-100, or about 10-500 bits.

[0097] Similar to the flip-flop circuit 306, in some embodiments, the retention latch circuit 308 may comprise one or more SR (“set-reset”) flip-flops, one or more D (“data” or “delay”) flip-flops, one or more T (“toggle”) flip-flops, and one or more JK flip-flops. The retention latch circuit 308 may be implemented using one or more pairs of cross-coupled inverting elements. In some embodiments, the retention latch circuit 308 may be implemented using one or more transistors, one or more inverters, and / or one or more logic gates. In some embodiments, the second binary data memory storage element 304 may be configured to retain a required portion of the data until the digital core (i.e., digital circuitry) of the implantable device detects that the implantable device has again begun to receive energy from an external power source. At this point, the digital core may reconnect the main power line to the energy storage, thereby causing the implantable device to enter a full-power “awake” mode. After the implantable device re-enters the "awake" mode, the digital core can cause the required data portion stored in the retention latch circuit 308 of the second binary data memory storage element 304 to be transmitted to the external device. A modulation circuit (e.g., modulation circuit 206 shown in FIG. 2) can be configured to encode the required data portion in a current flowing through a transmitter (e.g., transmitter 208 shown in FIG. 2) of the implantable device. In some embodiments, the transmitter can then emit backscattered waves (e.g., ultrasound backscattered waves or radio frequency backscattered waves) containing the encoded data. The emitted backscattered waves can be received by a transmitter of an external device (e.g., transmitter 228 of external device 224 shown in FIG. 2). After the backscattered waves are received by the external device, the essential data can be extracted from the backscattered waves.

[0098] An exemplary implementation of a first binary data memory storage element and a second binary data memory storage element, which may form components of a memory (e.g., memory 300) of an implantable device, is shown in Figure 9A. Figure 9A shows a retention D flip-flop 900 comprising a master latch circuit 902 connected in series with a slave latch circuit 904 that includes a retention latch circuit 906.

[0099] In some embodiments, the master latch 902 and the slave latch 904 may be coupled to a power management unit of the implantable device (e.g., the power management unit 202 of the implantable device 200 shown in FIG. 2) via a main power supply line. The retention latch 906 may additionally be coupled to the power management unit via a retention power supply line that is separate from the main power supply line.

[0100] The master latch 902 may be configured to receive a first input 908 and a second input 910. The second input 910 to the master latch 902 may comprise data (D) received from one or more sensors of the implantable device. The first input 908 to the master latch 902 may be a “clock” (C) signal configured to control the loading of data from the one or more sensors into the master latch 902 via the second input 910. In some embodiments, the implantable device may include a clock source (e.g., clock 236 of implantable device 200 shown in FIG. 2) configured to generate a clock signal. The clock signal generated by the clock source may be controlled by power management logic of the implantable device (e.g., power management logic 222 shown in FIG. 2). A digital core (e.g., digital core 204 shown in FIG. 2) may control when the clock signal is received by the flip-flop 900.

[0101] Similar to the master latch 902, the slave latch 904 may be configured to receive a clock signal 912. The clock signal 912 received by the slave latch 904 may control the loading of data from the master latch 902 to the slave latch 904. The retention latch 906 may be configured to receive an input 914. The input 914 to the retention latch 906 may be an “enable” (E) signal configured to cause the flip-flop 900 to control when data should be retained in the retention latch 906. The clock signal 912 and the enable signal 914 may be controlled by a digital core of the implantable device (e.g., digital core 204 shown in FIG. 2 ).

[0102] When the implantable device is operating in a full-power "awake" mode, the digital core of the implantable device can hold the enable signal 914 in a high (E=1) state. When the enable signal 914 is high, the retention D flip-flop 900 can act as a standard D flip-flop. Specifically, when the enable signal 914 is high, the slave latch 904 (including the retention latch 906) can act the same as a slave latch that does not include a retention latch structure.

[0103] While holding enable signal 914 in a high state, the digital core can control the loading and holding of data in master latch 902 and slave latch 904 by controlling clock signal 908 and clock signal 912. In some embodiments, when the digital core holds the clock in a low (C=0) state, master latch 902 can load data from one or more sensors of the implantable device via second master latch input 910 and slave latch 904 can hold the data. In some embodiments, when the digital core raises the clock to a high (C=1) state, master latch 902 can hold the data while slave latch 904 loads the data.

[0104] When the implantable device is operating in a low-power "sleep" mode, the digital core of the implantable device may hold the enable signal 914 in a low (E=0) state. When the enable signal 914 is low, the retention latch 906 may be configured to hold its value regardless of the value of the clock signal input to the slave latch 904. In some embodiments, the digital core may be configured to pull the enable signal 914 from a high state to a low state when it determines that one or more conditions related to the energy available in the device's power store have been met.

[0105] 9B shows an example implementation of the retention D flip-flop 900 shown in FIG. 9A. As shown, the master latch 902 can include an input inverter 918, a feedback inverter 924, and an output inverter 930, the slave latch 904 can include an input inverter 920, a feedback inverter 926, and an output inverter 932, and the retention latch 906 can include an input inverter 922, a feedback inverter 928, and an output inverter 934.

[0106] The feedback inverters 924 and 926 in the master latch 902 and the slave latch 904 may be configured to be enabled by the clock signal 908. The feedback inverter 928 in the retention latch 906 may be configured to be enabled by the enable signal 912. When the enable signal 912 is low (E=0), the input inverter 922 of the retention latch 906 may be disabled, while the feedback inverter 928 may be enabled. This may isolate the retention latch 906 from the other components of the flip-flop 900 and allow the retention latch 906 to retain its value regardless of the value of the clock signal 908; when the enable signal 912 is high (E=1), the feedback inverter 928 of the retention latch 906 may be disabled, while the input inverter 922 of the retention latch 906 may be enabled. This may allow flip-flop 900 to operate identically to a simple D flip-flop (ie, a D flip-flop without a retention latch structure).

[0107] Exemplary implementations of the output inverter, feedback inverter, and output input are shown in Figures 9C-9E, respectively. As shown, in some embodiments, the inverters may comprise one or more transistors 936. In some embodiments, the inverters used to form the retention latch 906 may be implemented using transistor devices with low leakage current to reduce the amount of power consumed by the retention latch 906.

[0108] 10 shows an exemplary method 1000 for storing data using the retention D flip-flop 900 shown in FIG. 9A. In some embodiments, method 1000 may be performed after determining that the implantable device is not receiving power from an external power source (e.g., because the external power source has been removed from the vicinity of the implantable device).

[0109] In step 1002, after the implantable device has been instructed to perform measurements of one or more physiological signals, the digital core of the implantable device may raise the retention latch's enable signal (e.g., enable signal 912) to a high (e=1) state so that the retention D flip-flop operates as a simple D flip-flop. Next, in step 1004, while the enable signal is held high, the digital core may lower the clock signal to a low (C=0) state so that the master latch can load data from one or more sensors. While the enable signal is held high and the clock signal is held low, method 1000 may proceed to step 1006, where the digital core may operate the device's sensors to measure one or more physiological signals.

[0110] After the sensor measures the physiological signal in step 1006, method 1000 may proceed to step 1008, where the digital core may raise the clock signal to a high (C=1) state, causing the data to be retained in the master latch and loaded into the slave latch. Method 1000 may then move to step 1010, where the digital core may lower the clock signal again to retain the data in the slave latch. Once the data is retained in the slave latch, method 1000 may proceed to step 1012, where the digital core may lower the enable signal to a low (E=0) state, causing the data to be retained in the retention latch. At this point, method 1000 may proceed to step 1014, where the main power line (i.e., the power line that provides energy to the implantable device while the device is operating in a full-power “awake” mode) may be disconnected from the device's power storage, and the device may enter a low-power “sleep” mode. While the device is in its low-power "sleep" mode, the digital core can hold the enable signal in a low (E=0) state to ensure that the data continues to be held in the retention latches.

[0111] External Devices As mentioned above, the implantable devices described herein receive energy from and communicate wirelessly with an external device. In some embodiments, the external device may be an interrogator comprising one or more transmitters (e.g., ultrasound transducers or RF antennas) configured to transmit energy to and receive energy from the implantable device. The interrogator may comprise power management circuitry configured to provide power to the one or more transmitters and communications circuitry configured to decode wireless communications received from the implantable device.

[0112] 4A shows an exemplary interrogator for providing energy to and communicating with an implantable device for measuring physiological signals (e.g., an intraocular implantable device for measuring intraocular pressure). An exemplary schematic diagram of an exemplary interrogator (i.e., an external device) for providing energy to and communicating with an implantable device is shown in FIG. 4B.

[0113] The interrogator of FIGS. 4A-4B may be configured to communicate wirelessly with an implantable device (e.g., an intraocular implantable device). The external device 400 may include one or more transducers 410 for wireless communication. In some embodiments, the one or more transducers 410 may include an ultrasound transducer. The ultrasound transducer may be configured to ultrasonically couple to the skin (e.g., the skin of the eyelid, the skin above the brow bone, the skin above the nasal bone, or the skin above the orbit in the case of an intraocular implantable device system) to facilitate ultrasonic communication between the external device and the implantable device (e.g., a device mounted on or in the eye). In some embodiments, an ultrasound coupling gel or alternative couplant may be used to ultrasonically couple the external device to the skin.

[0114] In some embodiments, the external device 400 may include ultrasound receiving and transmitting circuitry 420, a data interface 430, an embedded controller 440, and a power source 450. In some embodiments, the device may be configured to rely on power transmission from the external device. The power transmission from the external device may be used to power the device to initiate physiological signal measurements collected by one or more sensors of the implantable device. In some embodiments, one or more transducers 410 of the external device may be configured to transmit commands to the implantable device. Commands from the external device may instruct the device to reset itself, enter a particular mode, set device parameters, or initiate a transmission sequence.

[0115] Physical contact between the patient and the external device (e.g., between the patient's eye / eyelid and the external device) allows the external device to receive measurements from the implanted device. Optionally, the external device may be controlled using a separate computer system, such as a mobile device (e.g., a smartphone or table). The computer system may communicate wirelessly to the interrogator, for example, via a network connection, a radio frequency (RF) connection, or Bluetooth®. The computer system may, for example, turn the external device on or off or analyze information encoded in backscattered waves (e.g., ultrasound backscattered waves or radio frequency backscattered waves) received by the external device.

[0116] The implantable device and external device may communicate wirelessly with each other, for example, using ultrasound or radio frequency waves. The communication may be one-way (e.g., the external device sending information to the implantable device, or the implantable device sending information to the external device) or two-way (e.g., the interrogator sending information to the device, or the device sending information to the interrogator). The information transmitted from the device to the external device may depend, for example, on a backscatter communication protocol. For example, the external device may transmit ultrasound to the implantable device, which may emit backscattered waves that encode information. The external device can receive the backscattered waves and decode the information encoded in the received backscattered waves.

[0117] In some embodiments, one or more ultrasound transducers of the implantable device may include a piezoelectric crystal configured to receive commands from ultrasound energy transmitted from an external interrogator. The implantable device may decode pulse interval-encoded commands transmitted from the external interrogator and passively transmit data to the external device via amplitude-modulated backscatter communication. In some embodiments, the implanted device receives ultrasound waves from the external device through one or more ultrasound transducers on the implantable device, and the received waves may encode instructions for operating the implantable device. For example, vibration of an ultrasound transducer on the device generates a voltage across the transducer's electrical terminals, and a current flows through the device, including an integrated circuit. The current (which may be generated, for example, using one or more ultrasound transducers) may be used to charge an energy storage circuit.

[0118] In some embodiments, ultrasound backscatter is emitted from the implantable device, and the implantable device can encode information about the device. In some embodiments, the device is configured to detect physiological signals (e.g., intraocular pressure), and information about the detected physiological signal can be transmitted to an external device via ultrasound backscatter. To encode physiological signal information in the backscatter, the current flowing through the device's ultrasound transducer is modulated as a function of the encoded information, such as the measured physiological condition. In some embodiments, the modulation of the current can be, for example, an analog signal that can be directly modulated by the detected physiological condition. In some embodiments, the modulation of the current encodes a digitized signal that can be controlled by a digital core (i.e., digital circuitry) within an integrated circuit. The backscatter is received by an external device (which may be the same or different from the external device that transmitted the initial ultrasound). Thus, information can be encoded by changes in the amplitude, frequency, or phase of the backscattered ultrasound.

[0119] In some embodiments, the ultrasonic communication does not increase the temperature of any part of the eye by more than about 1.5°C for any period of time, in accordance with ISO 14708-01:2014 section 17, which specifies that the surface of the implant should not increase in temperature by more than 2°C.

[0120] In some embodiments, ultrasonic communication can be established when the piezoelectric crystal of the device is at a distance of about 5 mm + / - 20% from the external device. In some embodiments, ultrasonic communication can be established when the surface of the piezoelectric crystal is at most about 3 mm, 5 mm, 7 mm, or 9 mm from the surface of the external device configured to be in physical contact with the patient (e.g., configured to contact the skin of the eyelid, the skin above the brow bone, the skin above the nasal bone, or the skin above the orbit). In some embodiments, ultrasonic communication can be established when the surface of the piezoelectric crystal is at least about 1 mm, 2 mm, or 3 mm from an interrogator configured to be in physical contact with the subject (e.g., configured to contact the skin of the eyelid, the skin above the brow bone, the skin above the nasal bone, or the skin above the orbit). In some embodiments, ultrasonic communication can be established when the surface of the piezoelectric crystal is approximately 1-9 mm, 2-7 mm, or 3-5 mm from an external device configured to physically contact the patient (e.g., configured to contact the skin of the eyelid, the skin above the brow bone, the skin above the nasal bone, or the skin above the orbit). Once established, ultrasonic communication can withstand typical involuntary movements by the patient over the short period of physiological signal measurement (e.g., involuntary eye movements over the short period of IOP measurement).

[0121] FIG. 5 illustrates an exemplary interrogator in communication with an exemplary implantable device for measuring physiological signals (e.g., an intraocular implant for measuring intraocular pressure). An external ultrasound transceiver emits ultrasound waves ("carrier waves") that can pass through tissue. The carrier waves induce mechanical vibrations in an ultrasound transducer (e.g., a bulk piezoelectric transducer, PUMT, or CMUT). A voltage is generated across the ultrasound transducer, which imparts current through an integrated circuit on the implantable device. The current through the ultrasound transducer backscatters ultrasound waves to the transducer on the implantable device. In some embodiments, the integrated circuit modulates the current through the ultrasound transducer to encode information, and the resulting ultrasound backscattered waves encode the information. The backscattered waves can be detected by an external device and analyzed to interpret the information encoded in the ultrasound backscatter.

[0122] Instructions from the external device to the device can be carried by the ultrasound carrier. Specifically, the ultrasound carrier generated by the ultrasound transducer of the external device can include a series of ultrasound pulses with a varying number of carrier periods. The number of carrier periods encodes information specific to the device. For example, based on the number of carrier periods, the information can include instructions for the device to initiate a data transmission sequence. The transmission sequence can include steps for measuring physiological signal data (e.g., IOP data) and encoding the physiological signal data as ultrasound backscatter. The encoding includes backscattering the physiological signal data on the ultrasound carrier to modulate a current and converting the modulated current to ultrasound backscatter for transmission to the external device. The number of carrier periods can encode other information related to the device. For example, the information can include instructions for the device to reset itself, enter a particular mode, or set device parameters.

[0123] Communication between the external device and the implantable device can use a pulse-echo method of transmitting and receiving ultrasound. In the pulse-echo method, the interrogator transmits a series of interrogation pulses at a predetermined frequency and then receives backscattered echoes from the implanted device. In some embodiments, the pulses are square, rectangular, triangular, sawtooth, or sinusoidal. In some embodiments, the pulse output can be two-level (GND and POS), three-level (GND, NEG, POS), five-level, or any other multi-level (e.g., when using a 24-bit DAC). In some embodiments, pulses are transmitted continuously by the external device during operation. In some embodiments, when pulses are transmitted continuously by the interrogator, some of the transducers on the interrogator are configured to receive ultrasound and some of the transducers on the interrogator are configured to transmit ultrasound. The transducers configured to receive ultrasound and the transducers configured to transmit ultrasound can be on the same transducer array or different transducer arrays of the external device. In some embodiments, transducers on the external device can be alternatively configured to transmit or receive ultrasound. For example, the transducer may cycle between transmitting one or more pulses and a rest period, where the transducer is configured to transmit ultrasound when transmitting one or more pulses, and then switch to a receive mode during the rest period.

[0124] In some embodiments, the backscattered waves are digitized by the implantable device. For example, the implantable device can include an oscilloscope or an analog-to-digital converter (ADC) and / or memory, which can digitally encode information of current (or high-impedance) fluctuations. The digitized current fluctuations, which can encode information, are received by a wireless communication system, which then transmits the digitized ultrasound. The digitized data can be compressed from analog data, for example, by using singular value decomposition (SVD) and least-squares-based compression. In some embodiments, compression is performed by a correlator or pattern detection algorithm. The backscattered signals can undergo a series of nonlinear transformations, such as a fourth-order Butterworth bandpass filter rectified integration of the backscattered region, to generate reconstructed data points at a single time instance. Such transformations can be performed in either hardware (i.e., hard-coded) or software.

[0125] In some embodiments, the digitized signal compresses the size of the analog signal. The reduction in size of the digitized signal can allow for more efficient reporting of the information encoded in the backscatter. By compressing the size of the transmitted information through digitization, potentially overlapping signals can be transmitted accurately.

[0126] The wireless communication system can communicate with a separate device (e.g., an external interrogator or another apparatus). For example, the wireless communication can be configured to receive instructions from one or more sensors to emit ultrasound backscatter associated with measured physiological signal data (e.g., IOP data). The wireless communication system can include, for example, one or more ultrasound transducers. The wireless communication system can also be configured to receive energy (e.g., via ultrasound) from another device that can be used to power the implantable device.

[0127] In addition to providing instructions to the device, in some embodiments, an ultrasonic carrier from the interrogator can transmit vibrational energy configured to power the device, i.e., ultrasonic pulses of the ultrasonic carrier are delivered to the device at a frequency suitable to provide energy to power the ASIC.

[0128] In some embodiments, the implantable device may also be operated to transmit information (i.e., uplink communications) through a wireless communication system that can be received by an interrogator. In some embodiments, the wireless communication system is configured to actively generate communication signals (e.g., ultrasound waves) that encode information. In some embodiments, the wireless communication system is configured to transmit information encoded on backscattered waves (e.g., ultrasound backscattered waves). Backscattered communications provide a lower-power method of transmitting information, which is particularly beneficial for small devices to minimize energy use. By way of example, the wireless communication system may include one or more ultrasound transducers configured to receive ultrasound waves and emit ultrasound backscatter that can encode information transmitted by the implantable device. A current flows through the ultrasound transducers, which may be modulated to encode the information. The current may be modulated directly, for example, by passing the current through a sensor that modulates the current, or indirectly, for example, by modulating the current using modulation circuitry based on a detected physiological condition such as IOP.

[0129] Information transmitted wirelessly using a wireless communication system can be received by an interrogator. In some embodiments, information is transmitted by encoding it in backscattered waves (e.g., ultrasound backscatter). The backscatter can be received by an interrogator, for example, and decoded to determine the encoded information. Further details regarding backscattered communication are provided herein, and further examples are provided in WO 2018 / 009905, WO 2018 / 009908, WO 2018 / 0091010, WO 2018 / 009911, WO 2018 / 009912, International Patent Application No. PCT / US2019 / 028381, International Patent Application No. PCT / US2019 / 028385, and International Patent Application No. PCT / 2019 / 048647, each of which is incorporated herein by reference for all purposes. Information can be encoded by an integrated circuit using a modulation circuit. The modulation circuit is part of a wireless communication system and may be operated by or contained within an integrated circuit.

[0130] Method for storing and retrieving data on an implantable device - Patent Application 20070122997 As described in the previous section, an implantable device for sensing one or more physiological signals may include memory elements configured to retain small amounts of data using negligible energy while other portions of the device are in a low-power “sleep” mode. One or more processors (e.g., digital cores) of the implantable device may be configured to control how data detected by one or more sensors of the implantable device is stored based on the device's current power state (e.g., based on whether the implantable device is currently receiving power from an external power source or based on the amount of energy currently available in the implantable device's energy storage). In some embodiments, one or more processors (e.g., digital cores) of the implantable device may be configured to selectively disconnect and reconnect one or more elements of the implantable device's memory from the implantable device's power management unit to conserve energy when the device is not receiving power from an external power source.

[0131] FIG. 6A illustrates an exemplary method for storing data using an implantable device, according to some embodiments of the present disclosure. Specifically, FIG. 6A illustrates a method 600 for allocating a required portion of data stored in a first element of memory of an implantable device to a second element of memory that constantly receives energy from the device's power supply. In some embodiments, method 600 may be performed by a digital core of the implantable device (e.g., digital core 204 of implantable device 200 shown in FIG. 2). Prior to performing a method for storing data (e.g., method 600), the implantable device may continuously receive energy from an external power source. In some embodiments, prior to performing a method for storing data (e.g., method 600), all elements of the implantable device may be fully “awake,” i.e., electrically coupled to and receiving energy from the implantable device's power supply.

[0132] In some embodiments, the memory of the implantable device may include one or more features of memory 212 of implantable device 200 (shown in FIG. 2 ). In particular, the first and second elements of the memory may comprise one or more features of first binary data memory storage element 214 and second binary data memory storage element 216, respectively. In some embodiments, the first element of the memory may be electrically coupled to the device's energy storage via a main power supply line (e.g., main power supply line 232), and the second element of the memory may be electrically coupled to the device's energy storage via a separate retention power supply line (e.g., retention power supply line 234). The main power supply line may continuously supply energy to the first element of the memory, as well as other elements of the implantable device (e.g., one or more sensors), prior to performing a method for storing data by the digital core (e.g., method 600). Similarly, the retention power supply line may continuously supply energy to the second element of the memory prior to performing a method for storing data by the digital core (e.g., method 600).

[0133] In some embodiments, method 600 may begin at step 602, where the digital core may determine that an energy storage in a power management unit of the implantable device is no longer receiving energy from the external power source. In some embodiments, determining that the implantable device is no longer receiving energy from the external power source may include receiving one or more signals from the external power source and / or from a user indicating that energy is no longer being provided to the energy storage.

[0134] Optionally, after the digital core determines in step 602 that the implantable device is no longer receiving energy from the external power source, method 600 may proceed to step 604, where the digital core may cause one or more sensors of the implantable device to measure one or more physiological signals. Data related to the measured physiological signals may be transmitted from the one or more sensors to a first element of memory of the implantable device.

[0135] In some embodiments, sensing physiological signals when the implantable device is not receiving energy from an external power source can prevent the external power source from affecting the measurement. For example, an implantable device may be configured to be implanted in an eye to measure intraocular pressure. The intraocular implant may be configured to receive energy in the form of ultrasound from an interrogator. Specifically, the implant may receive energy from the interrogator when the interrogator is pressed against the eye. Intraocular pressure within the eye may be affected by contact between the interrogator and the eye. Once the interrogator no longer provides energy to the implant (i.e., once the interrogator is no longer in contact with the eye), the implant can provide an accurate measurement of intraocular pressure.

[0136] In some embodiments, after the digital core determines that the implantable device is no longer receiving energy from the external power source in step 602 (and, optionally, after physiological signal measurements are performed in step 604), method 600 may proceed to step 606, where the digital core may detect that a predetermined condition has been met. In some embodiments, the predetermined condition may be associated with the amount of time that has elapsed since the processor (e.g., the digital core) determined that the implantable device is no longer receiving energy from the external power source. In some embodiments, the predetermined condition may be associated with a threshold amount of energy that the implantable device's energy storage must store to ensure a requisite amount of data can be stored in the device's memory for an extended period of time. In some embodiments, the predetermined condition may be associated with the amount of data collected.

[0137] In some embodiments, after the digital core detects that the predetermined condition has been met in step 606, method 600 may proceed to step 608, where the digital core may transmit a required portion of the data stored in the first element of the implantable device's memory to a second element of the implantable device's memory (e.g., a second binary data memory storage element) electrically coupled to the energy storage via the retention power line. In some embodiments, the required portion of the data transmitted from the first element of the device's memory to the second element of the device's memory may include data related to a measurement performed at a particular time, such as data related to a measurement performed most recently.

[0138] In some embodiments, after the digital core transfers a required portion of data stored in a first element of memory of the implantable device to a second element of memory of the implantable device, method 600 may proceed to step 610, where a processor (e.g., the digital core) may disconnect a main power line from an energy storage in a power management unit of the device. In some embodiments, the digital core may use the power management unit to disconnect the main power line. As described above, the main power line may electrically couple the first element of memory of the device to the energy storage. In some embodiments, the main power line may electrically couple a sensor or other element of the implantable device to the energy storage. In some embodiments, disconnecting the main power line from the energy storage may prevent the first element of memory of the device (another element connected to the main power line) from drawing energy stored in the energy storage. In some embodiments, disconnecting the main power line from the power management unit may cause one or more elements of the implantable device to enter a low-power “sleep” mode.

[0139] The retention power line electrically coupling the second element of the device's memory (which stores the essential portion of the data stored in the first element) may remain connected to the energy storage after the main power line is disconnected in step 610. The second element of the device's memory may be configured to store the essential portion of the data while drawing very little power from the energy storage. In some embodiments, the second element of the device's memory may be configured to store the essential portion of the data using 10, 30, 50, 70, or 100 picowatts or less of power from the device's energy storage. In some embodiments, the second element of the device's memory may be configured to store the essential portion of the data using 100, 1000, 5000, 10 ... 4 , or 10 5The device may be configured to store a required portion of the data using power from the device's energy storage of picowatts or more. In some embodiments, a second element of the device's memory may be configured to store 50-150, 100-200, 100-1000, or 100-1000 picowatts of power from the device's energy storage. 4 It may be configured to store a substantial portion of the device's memory using picowatts of power, and a second element of the device's memory may store the essential portion of the data until the implantable device begins to receive energy from an external power source again.

[0140] 6B illustrates an exemplary method 606 for detecting that a predetermined condition associated with an implantable device has been met, according to some embodiments of the present disclosure. Specifically, FIG. 6B illustrates an exemplary method 606 for determining that a threshold time has elapsed since one or more processors (e.g., digital cores) of the implantable device determined that the implantable device is no longer receiving energy from an external power source. Method 606 may be performed during step 606 of method 600 illustrated in FIG. 6A.

[0141] Method 606 may include step 612, in which a timer countdown may be initiated with the timer preset to a threshold time period. The timer may be a component of the digital core. In some embodiments, the countdown may be initiated by the digital core of the implantable device after the digital core detects that the implantable device is no longer receiving energy from the external power source. In some embodiments, the threshold period may be 10, 30, 60, 90, or 120 seconds or less. In some embodiments, the threshold period may be 10, 30, 60, 90, or 120 seconds or more.

[0142] Once the countdown is complete, method 406 may proceed to step 414, where the digital core may determine that the threshold time period has been exceeded. At this point, the digital core may initiate one or more steps (e.g., steps 608-610 of method 600 shown in FIG. 6A) intended to place the implantable device into a low-power "sleep" mode.

[0143] 6C illustrates an exemplary method for detecting that a predetermined condition associated with an implantable device has been met, according to some embodiments of the present disclosure. Specifically, FIG. 6C illustrates a method 606 for determining that the total amount of power stored in the implantable device's power supply has dropped below a threshold power level. Method 606 may be performed during step 606 of method 600 shown in FIG. 6A.

[0144] Method 606 may include step 612, in which a digital core of the implantable device may begin monitoring the total power level of the device's energy storage. In some embodiments, power level monitoring may be initiated by the digital core of the implantable device after the digital core detects that the implantable device is no longer receiving energy from an external power source.

[0145] In some embodiments, after power level monitoring is initiated in step 606, method 606 may proceed to step 614, where one or more processors (e.g., digital cores) may determine that the amount of power remaining in the device's power supply has fallen below a threshold power level. At this point, the processors (e.g., digital cores) may initiate one or more steps (e.g., steps 608-610 of method 600 shown in FIG. 6A) intended to place the implantable device in a low-power "sleep" mode.

[0146] In some embodiments, the threshold power level may depend on the operating voltage level of a retention cell in a second element of the device's memory (e.g., retention latch 308 in second binary data memory storage element 304 shown in FIG. 3 ). For example, the energy storage of the implantable device may be a 1 μF capacitor. The device's retention cell may be configured to store data at a voltage greater than 0.4 V and draw 1 nA of current. The device's processor (e.g., digital core) may be configured to ensure that the retention cell is capable of storing data for a predetermined amount of time, e.g., approximately 26 minutes. Accordingly, the processor (e.g., digital core) may be configured to cause the device to enter a low-power “sleep” mode (i.e., a mode in which the majority of the device's power is drawn by the capacitor) whenever the device is not receiving energy from an external power source and the capacitor's voltage drops below 2 V. Note that this example is presented for illustrative purposes only and is not intended to limit the present disclosure.

[0147] FIG. 7 illustrates an exemplary method for transferring data stored in an implantable device's memory to an external device. Specifically, FIG. 7 illustrates a method 700 for transferring data stored in an implantable device's memory to an external device using backscattered waves. In some embodiments, method 700 may be performed after the implantable device has returned to a full-power “awake” mode following a period in which the implantable device was in a low-power “sleep” mode. In such a situation, essential data related to measurements completed before the device entered the low-power “sleep” mode may be stored in a second binary data memory storage element of the implantable device's memory (i.e., a binary data memory storage element configured to continuously receive power from the device's energy storage while the device was in the “sleep” mode, e.g., second binary data memory storage element 216 shown in FIG. 2 ).

[0148] The implantable device may return to a full-power "awake" mode when the external energy source resumes transferring energy to the device's power management unit. In some embodiments, when the amount of energy in the device's energy storage increases above a minimum threshold level, the device's processor (e.g., digital core) may reconnect the device's main power line to the power management unit. Once the main power line is reconnected to the power management unit, data input / output circuitry of the device that can receive power via the main power line can begin to function. At this point, method 700 may begin.

[0149] In some embodiments, method 700 may begin at step 702, where a digital core of the device may retrieve data stored in a second binary data memory storage element of the device's memory. Method 700 may then proceed to step 704, where modulation circuitry of the implantable device may encode information describing the data in a current flowing through a transmitter (e.g., transducer) of the implantable device.

[0150] After the information describing the data is encoded in the current flowing through the transmitter in step 704, method 700 may proceed to step 706, where the transmitter may emit backscattered waves with the information encoded in the current. In some embodiments, the backscattered waves may be ultrasound waves. In some embodiments, the backscattered waves may be radio frequency waves. Method 700 then proceeds to step 708, where the emitted backscattered waves may be received by an external device. Once the emitted backscattered waves are received by the external device, method 700 proceeds to step 710, where the information carried by the backscattered waves may be extracted from the backscattered waves.

[0151] 8 illustrates an exemplary method 800 for measuring intraocular pressure using an exemplary intraocular implant, storing intraocular pressure data when the implant is in a low-power "sleep" mode, and transmitting the intraocular pressure data to an interrogator. Method 800 may allow IOP data to be stored by the ocular implant for extended periods of time before being retrieved by the interrogator without depleting energy storage on the device.

[0152] In some embodiments, method 800 may begin at step 802, where an interrogator may be positioned proximal to the subject's eye where the ocular implant is to be implanted. Method 800 may then proceed to step 804, where the ocular implant may receive energy in the form of ultrasound from the interrogator.

[0153] After the implantable device has received a sufficient amount of energy from the interrogator, the interrogator may be removed from a position proximal to the subject's eye in step 806. Method 800 then proceeds to step 808, where one or more pressure sensors within the intraocular implant may be used to measure an intraocular pressure signal. The one or more sensors may then transmit data related to the measured IOP to a first binary data memory storage element of the memory of the ocular implant in step 810. The first binary data memory storage element and the one or more sensors may be electrically coupled to an energy storage via a main power line. As measurements are made by the sensors and data is stored by the first binary data memory storage element, the amount of energy stored in the energy storage may be reduced.

[0154] In some embodiments, method 800 may proceed from step 810 to step 812, where the digital core of the ocular implant may detect a predetermined condition related to the amount of energy remaining in the intraocular implant's energy storage (see, e.g., example method 606 shown in FIGS. 4B-4C). Upon detecting that the predetermined condition has been met, method 800 may proceed to step 814, where the digital core may cause a portion of the IOP data stored in the first binary data memory storage element to be transferred to a second binary data memory storage element coupled to the energy storage via a retention power line. Method 800 may then proceed to step 816, where the main power line may be disconnected from the energy storage, causing the implantable device to enter a low-power "sleep" mode.

[0155] When the user is ready to retrieve the data stored in the "asleep" intraocular implant, the user may perform step 818 by repositioning the interrogator to a position proximal to the patient's eye. Once the interrogator has been repositioned, method 800 may move to step 820, where the IOP data stored in the second binary data memory storage element may be transferred to the interrogator as described in the previous section.

[0156] The foregoing description has been described with reference to specific embodiments for purposes of explanation. However, the illustrative discussion above is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. The embodiments were chosen and described in order to best explain the principles of the technology and their practical application, thereby enabling those skilled in the art to best utilize the technology and various embodiments with various modifications as suited to the particular use contemplated.

[0157] Although the present disclosure and examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art, and such changes and modifications are to be understood as being included within the scope of the present disclosure and examples as defined by the claims.

[0158] Any of the systems, methods, techniques, and / or features disclosed herein may be combined, in whole or in part, with any other system, method, technique, and / or feature disclosed herein.

Claims

1. 1. An implantable device comprising: an energy storage device configured to receive power from an external power source; one or more sensors configured to measure physiological signals; a memory configured to store physiological signal data measured by the one or more sensors, a first binary data memory storage element electrically coupled to the one or more sensors and to a main power line electrically coupled to the energy storage; a second binary data memory storage element electrically coupled to the first binary data memory storage element and to a retention power supply line electrically coupled to an energy storage; a memory comprising: A digital circuit comprising: determining that the power management unit is not receiving power from the external power source; Detecting that a predetermined condition has been met, storing a required portion of the physiological signal data measured by the one or more sensors in the second binary data memory storage element; disconnecting the main power line from the energy storage; A digital circuit configured as follows: An implantable device comprising:

2. 2. The implantable device of claim 1, wherein the main power supply line is configured to transfer a first amount of power from the energy storage to the first binary data memory storage element, and the retention power supply line is configured to transfer a second amount of power from the energy storage to the second binary data memory storage element.

3. The implantable device of claim 2 , wherein the second amount of power is less than the first amount of power.

4. 4. The implantable device of claim 2 or 3, wherein the second amount of power is 100 picowatts or less.

5. The implantable device of claim 1 , wherein the essential portion of the physiological signal data stored in the second binary data memory storage element includes data relating to a most recently performed measurement.

6. The implantable device of claim 1 , wherein the one or more sensors comprise a pressure sensor.

7. The implantable device of claim 6 , wherein the pressure sensor is configured to measure intraocular pressure.

8. The implantable device of claim 1 , wherein the one or more sensors comprise one or more electrodes configured to detect electrophysiological pulses.

9. 9. The implantable device of claim 1, wherein the one or more sensors comprise sensors configured to detect analyte concentration, pH, temperature, evoked action potentials in the brain, and / or local field potentials in the brain.

10. 10. The implantable device of claim 1, wherein the device is configured to be fully implantable.

11. 11. The implantable device of any one of claims 1 to 10, wherein the device is configured to be implanted or attached to a tissue or organ.

12. The implantable device of claim 11 , wherein the device is configured to be implanted in the eye.

13. The implantable device of claim 11 , wherein the device is configured to be implanted on or in central nervous tissue.

14. The implantable device of claim 11 , wherein the device is configured to be implanted on or in the brain.

15. The implantable device of claim 11 , wherein the device is configured to be implanted over a peripheral nerve.

16. The implantable device of claim 15 , wherein the peripheral nerve is a splenic nerve.

17. The implantable device of claim 1 , wherein the energy storage is configured to receive power wirelessly from the external power source.

18. The implantable device of claim 1 , wherein the energy storage is configured to receive power from ultrasound generated by the external power source.

19. The implantable device of claim 1 , wherein the energy storage is configured to receive power from radio frequency waves generated by the external power source.

20. 20. The implantable device of claim 1, wherein the energy storage is configured to receive power from the external power source via induction.

21. The implantable device of claim 1 , wherein the energy storage is configured to receive power from the external power source via a capacitive link.

22. 22. The implantable device of any one of claims 1 to 21, wherein the energy storage is configured to receive power from vibrations generated by the external power source using a vibration transducer.

23. 23. The implantable device of any one of claims 1 to 22, wherein the energy storage comprises a capacitor.

24. 24. The implantable device of any one of claims 1 to 23, wherein the energy storage comprises a battery.

25. 25. The implantable device of claim 1, wherein detecting that the predetermined condition has been met comprises determining that a threshold period of time has passed since the time the energy storage last received power from the external device.

26. 26. The implantable device of claim 1, wherein detecting that the predetermined condition has been met comprises detecting that a total power level of the energy storage has fallen below a threshold power level.

27. 27. The implantable device of claim 1, wherein the first binary data memory storage element comprises a flip-flop circuit.

28. 28. The implantable device of claim 1, wherein the second binary data memory storage element comprises a retention latch circuit.

29. 1. A method for collecting and storing data using an implantable device, comprising: The implantable device comprises: an energy storage device configured to receive power from an external power source; one or more sensors configured to measure physiological signals; a memory configured to store physiological signal data measured by the one or more sensors, a first binary data memory storage element electrically coupled to the one or more sensors and to a main power line electrically coupled to the energy storage; a second binary data memory storage element electrically coupled to the first binary data memory storage element and to a retention power supply line electrically coupled to the energy storage; a memory comprising: Digital circuits and The method comprises: determining that the energy storage is not receiving power from the external power source; Detecting that a predetermined condition is met; storing a required portion of the physiological signal data measured by the one or more sensors in the second binary data memory storage element; disconnecting the main power line from the energy storage; A method comprising:

30. 30. The method of claim 29, wherein the main power supply line is configured to transfer a first amount of power from the power supply to the first binary data memory storage element, and the retention power supply line is configured to transfer a second amount of power from the power supply to the second binary data memory storage element.

31. 31. The method of claim 30, wherein the second amount of power is less than the first amount of power.

32. 32. The method of claim 30 or 31, wherein the second amount of power is 100 picowatts or less.

33. 33. The method of any one of claims 29 to 32, wherein the essential portion of the physiological signal data stored in the second binary data memory storage element comprises data relating to a most recently performed measurement.

34. 34. The method of any one of claims 29 to 33, wherein the one or more sensors comprise a pressure sensor.

35. 35. The method of claim 34, wherein the pressure sensor is configured to measure intraocular pressure.

36. 36. The method of any one of claims 29 to 35, wherein the one or more sensors comprise one or more electrodes configured to detect electrophysiological pulses.

37. 37. The method of any one of claims 29 to 36, wherein the one or more sensors comprise sensors configured to detect analyte concentration, pH, temperature, and / or evoked action potentials in the brain, and / or local field potentials in the brain.

38. 38. The method of any one of claims 29 to 37, wherein the device is configured to be fully implantable.

39. 39. The method of any one of claims 29 to 38, wherein the device is configured to be implanted or attached to a tissue or organ.

40. 40. The method of claim 39, wherein the device is configured to be implanted in the eye.

41. 40. The method of claim 39, wherein the device is configured to be implanted on or in central nervous tissue.

42. 40. The method of claim 39, wherein the device is configured to be implanted on or in the brain.

43. 40. The method of claim 39, wherein the device is configured to be implanted over a peripheral nerve.

44. 44. The method of claim 43, wherein the peripheral nerve is a splenic nerve.

45. 45. The method of any one of claims 29 to 44, wherein the energy storage is configured to receive power wirelessly from the external power source.

46. 46. ​​The method of any one of claims 29 to 45, wherein the energy storage is configured to receive power from ultrasound generated by the external power source.

47. 47. The method of any one of claims 29 to 46, wherein the energy storage is configured to receive power from radio frequency waves generated by the external power source.

48. 48. The method of any one of claims 29 to 47, wherein the energy storage is configured to receive power from the external power source via induction.

49. 49. The method of any one of claims 29 to 48, wherein the energy storage is configured to receive power from the external power source via a capacitive link.

50. 50. The method of any one of claims 29 to 49, wherein the energy storage is configured to receive power from vibrations generated by the external power source using a vibration transducer.

51. 51. The method of any one of claims 29 to 50, wherein the energy storage comprises a capacitor.

52. 52. The method of any one of claims 29 to 51, wherein the energy storage comprises a battery.

53. 53. The method of any one of claims 29 to 52, wherein detecting that the predetermined condition has been met comprises determining that a threshold period of time has passed since the time the energy storage last received power from the external device.

54. 54. The method of any one of claims 29 to 53, wherein detecting that the predetermined condition has been met comprises detecting that a total power level of the energy storage has fallen below a threshold power level.

55. 55. The method of any one of claims 29 to 54, wherein the first binary data memory storage element comprises a flip-flop circuit.

56. 56. The method of any one of claims 29 to 55, wherein the second binary data memory storage element comprises a retention latch circuit.

57. 1. A non-transitory computer-readable storage medium comprising instructions for collecting and storing data in an implantable device, the implantable device comprising: an energy storage configured to receive power from an external power source; one or more sensors configured to measure physiological signals; a memory configured to store physiological signal data measured by the one or more sensors, a first binary data memory storage element electrically coupled to the one or more sensors and to a main power line electrically coupled to the energy storage; a second binary data memory storage element electrically coupled to the first binary data memory storage element and to a retention power supply line electrically coupled to the energy storage; a memory comprising: The instructions, when executed by digital circuitry of an electronic device, cause the electronic device to: determining that the energy storage is not receiving power from the external power source; Detecting that a predetermined condition has been met, storing a required portion of the physiological signal data measured by the one or more sensors in the second binary data memory storage element; A non-transitory computer-readable storage medium that causes the main power line to be disconnected from the energy storage.

58. 58. The non-transitory computer-readable storage medium of claim 57, wherein the main power line is configured to transfer a first amount of power from the power source to the first binary data memory storage element, and the retention power line is configured to transfer a second amount of power from the power source to the second binary data memory storage element.

59. 60. The non-transitory computer-readable storage medium of claim 58, wherein the second amount of power is less than the first amount of power.

60. 60. The non-transitory computer-readable storage medium of claim 58 or 59, wherein the second amount of power is 100 picowatts or less.

61. 61. The non-transitory computer-readable storage medium of any one of claims 57 to 60, wherein the essential portion of the data stored in the second binary data memory storage element includes data relating to a most recently performed measurement.

62. 62. The non-transitory computer-readable storage medium of any one of claims 57 to 61, wherein the one or more sensors comprise a pressure sensor.

63. 63. The non-transitory computer-readable storage medium of claim 62, wherein the pressure sensor is configured to measure intraocular pressure.

64. 64. The non-transitory computer-readable storage medium of any one of claims 57 to 63, wherein the one or more sensors comprise one or more electrodes configured to detect electrophysiological pulses.

65. 65. The non-transitory computer-readable storage medium of any one of claims 57 to 64, wherein the one or more sensors comprise sensors configured to detect analyte concentration, pH, temperature, evoked action potentials in the brain, and / or local field potentials in the brain.

66. 66. The non-transitory computer-readable storage medium of any one of claims 57 to 65, wherein the device is configured to be fully implantable.

67. 67. The non-transitory computer-readable storage medium of any one of claims 57 to 66, wherein the device is configured to be implanted or attached to a tissue or organ.

68. 68. The non-transitory computer-readable storage medium of claim 67, wherein the device is configured to be implanted in an eye.

69. 68. The non-transitory computer-readable storage medium of claim 67, wherein the device is configured to be implanted on or in central nervous tissue.

70. 68. The non-transitory computer-readable storage medium of claim 67, wherein the device is configured to be implanted on or in the brain.

71. 68. The non-transitory computer-readable storage medium of claim 67, wherein the device is configured to be implanted over a peripheral nerve.

72. 72. The non-transitory computer-readable storage medium of claim 71, wherein the peripheral nerve is a splenic nerve.

73. 73. The non-transitory computer-readable storage medium of any one of claims 57 to 72, wherein the energy storage is configured to receive power wirelessly from the external power source.

74. 74. The non-transitory computer-readable storage medium of any one of claims 57 to 73, wherein the energy storage is configured to receive power from ultrasound generated by the external power source.

75. 75. The non-transitory computer-readable storage medium of any one of claims 57 to 74, wherein the energy storage is configured to receive power from radio frequency waves generated by the external power source.

76. 76. The non-transitory computer-readable storage medium of any one of claims 57 to 75, wherein the energy storage is configured to receive power from the external power source via induction.

77. 77. The non-transitory computer-readable storage medium of any one of claims 57 to 76, wherein the energy storage is configured to receive power from the external power source via a capacitive link.

78. 78. The non-transitory computer-readable storage medium of any one of claims 57 to 77, wherein the energy storage is configured to receive power from vibrations generated by the external power source using a vibration transducer.

79. 79. The non-transitory computer-readable storage medium of any one of claims 57 to 78, wherein the energy storage comprises a capacitor.

80. 80. The non-transitory computer-readable storage medium of any one of claims 57 to 79, wherein the energy storage comprises a battery.

81. 81. The non-transitory computer-readable storage medium of any one of claims 57 to 80, wherein detecting that the predetermined condition has been met comprises determining that a threshold period of time has passed since the time the energy storage last received power from the external device.

82. 82. The non-transitory computer-readable storage medium of any one of claims 57 to 81, wherein detecting that the predetermined condition has been met comprises detecting that a total power level of the energy storage has fallen below a threshold power level.

83. 83. The non-transitory computer-readable storage medium of any one of claims 57 to 82, wherein the first binary data memory storage element comprises a flip-flop circuit.

84. 84. The non-transitory computer-readable storage medium of any one of claims 57 to 83, wherein the second binary data memory storage element comprises a retention latch circuit.

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