摘要:
Various techniques are described for periodically performing a calibration routine to calibrate a low-power system clock within an implantable medical device (IMD) based on a high accuracy reference clock also included in the IMD. The system clock is powered continuously, and the reference clock is only powered on during the calibration routine. The techniques include determining a clock error of the system clock based on a difference between frequencies of the system clock and the reference clock over a fixed number of clock cycles, and adjusting a trim value of the system clock to compensate for the clock error. Calibrating the system clock with a delta-sigma loop, for example, reduces the clock error over time. This allows accurate adjustment of the system clock to compensate for errors due to trim resolution, circuit noise and temperature.
摘要:
Various techniques are described for periodically performing a calibration routine to calibrate a low-power system clock within an implantable medical device (IMD) based on a high accuracy reference clock also included in the IMD. The system clock is powered continuously, and the reference clock is only powered on during the calibration routine. The techniques include determining a clock error of the system clock based on a difference between frequencies of the system clock and the reference clock over a fixed number of clock cycles, and adjusting a trim value of the system clock to compensate for the clock error. Calibrating the system clock with a delta-sigma loop, for example, reduces the clock error over time. This allows accurate adjustment of the system clock to compensate for errors due to trim resolution, circuit noise and temperature.
摘要:
A pressure sensing system provides signals representative of a magnitude of pressure at a selected site. A sensor module includes a first transducer producing a first signal having an associated first response to pressure and strain applied to the sensor module and a second transducer producing a second signal having an associated second response to pressure and strain applied to the sensor module. A calculated pressure, a bending pressure error and a bend-compensated pressure are computed in response to the first signal and the second signal.
摘要:
An implantable medical device having an optical sensor selects the function of modular opto-electronic assemblies included in the optical sensor. Each assembly is provided with at least one light emitting device and at least one light detecting device. A device controller coupled to the optical sensor controls the function of each the assemblies. The controller executes a sensor performance test and selects at least one of the plurality of assemblies to operate as a light emitting assembly in response to a result of the performance test. The controller selects at least one other of the plurality of optical sensor assemblies to operate as a light detecting assembly in response to a result of the performance test.
摘要:
This disclosure relates to fault tolerant instantiations of a cardiac therapy delivery device such as an implantable cardiac stimulator (e.g., an implantable pulse generator, IPG, and/or an implantable cardioverter-defibrillator, ICD) coupled to an implantable physiologic sensor (IPS). According to the disclosure delivery of cardiac pacing and/or cardioversion-defibrillator therapy delivery can cause errors in output signals from an IPS. Resolution of such errors involves selectively energizing (or disconnecting the output signal from) the IPS during pacing and/or defibrillation therapy delivery. Programmable signal “blanking” in lieu of or in addition to the foregoing also improves the integrity of the output signal (i.e., continuously energize the IPS and ignore parts of the output signal). An ICD having a transient weakness in an insulated conductor used for the IPS signal can likewise have the IPS de-energized and/or blank the IPS output signal during high voltage therapy delivery.
摘要:
A radiation-based timer for use in an implantable medical device (IMD) includes a radiation source and a radiation detection circuit. The radiation source emits radiation particles during a process referred to as radioactive decay. The radiation detection circuit detects the radiation particles emitted during the decay process and tracks the number of radiation particles detected. When the number of radiation particles detected reaches a threshold value, a timer signal is generated. In this manner, the radiation-based timer generates a timer signal as a function of the radioactive decay of the radiation source. The timer signal may be used by one or more components of the IMD for any of a number of functions, including as a wakeup trigger for a communications and/or a sensor event.
摘要:
A pressure sensing system provides signals representative of a magnitude of pressure at a selected site. A sensor module includes a first transducer producing a first signal having an associated first response to pressure and strain applied to the sensor module and a second transducer producing a second signal having an associated second response to pressure and strain applied to the sensor module. A calculated pressure, a bending pressure error and a bend-compensated pressure are computed in response to the first signal and the second signal.
摘要:
A radiation-based timer for use in an implantable medical device (IMD) includes a radiation source and a radiation detection circuit. The radiation source emits radiation particles during a process referred to as radioactive decay. The radiation detection circuit detects the radiation particles emitted during the decay process and tracks the number of radiation particles detected. When the number of radiation particles detected reaches a threshold value, a timer signal is generated. In this manner, the radiation-based timer generates a timer signal as a function of the radioactive decay of the radiation source. The timer signal may be used by one or more components of the IMD for any of a number of functions, including as a wakeup trigger for a communications and/or a sensor event.
摘要:
An implantable medical device includes a hermetically sealed housing and a first light emitting diode (LED) enclosed within the housing configured to detect light corresponding to a selected light wavelength. A conductive element extends from the LED for carrying a current signal corresponding to the light detected by the LED, the intensity of the detected light being correlated to a change in a physiological condition in a body fluid volume or a tissue volume proximate the LED.
摘要:
A reflectance-type optical sensor includes one or more photodiodes formed in a semiconductor substrate. A well having sidewalls and a bottom is formed in the top surface of the substrate, and a reflective layer is formed on the sidewalls and bottom. A light-emitting diode (LED) is mounted in the well, so that light emitted laterally and rearwardly from the LED strikes the sidewalls or bottom and is redirected in a direction generally perpendicular to the top surface of the substrate. The optical sensor can be fabricated using microelectromechanical systems (MEMS) fabrication techniques.