摘要:
This disclosure describes techniques for generating stimulation current pulses that have differing pulse shapes in a medical device. A circuit architecture is described that is configured to charge a capacitor to an initial amount of charge, modulate the amount of charge stored in the capacitor based on a control signal, and generate a stimulation current pulse that has an amplitude based on the amount charge stored in the capacitor. The circuit architecture may be configured to generate complex pulse shapes, such as, e.g., steps, ramps, bursts, and combinations thereof.
摘要:
This disclosure describes techniques for generating stimulation current pulses that have differing pulse shapes in a medical device. A circuit architecture is described that is configured to charge a capacitor to an initial amount of charge, modulate the amount of charge stored in the capacitor based on a control signal, and generate a stimulation current pulse that has an amplitude based on the amount charge stored in the capacitor. The circuit architecture may be configured to generate complex pulse shapes, such as, e.g., steps, ramps, bursts, and combinations thereof.
摘要:
In general, this disclosure is directed to a mixer amplifier that can be utilized within a chopper stabilized instrumentation amplifier. The chopper stabilized instrumentation amplifier may be used for physiological signal sensing, impedance sensing, telemetry or other test and measurement applications. In some examples, the mixer amplifier may include a current source configured to generate a modulated current at a modulation frequency for application to a load to produce an input signal, an amplifier configured to amplify the input signal to produce an amplified signal, and a demodulator configured to demodulate the amplified signal at the modulation frequency to produce an output signal indicating an impedance of the load.
摘要:
A system and method for determining complex intercardiac impedance to detect various cardiac functions are disclosed involving a signal generator means for providing an adjustable direct current signal, a modulator for modulating the adjustable direct current signal to produce a modulated signal, at least one electrode for propagating the modulated signal across a myocardium, at least one sensor for detecting an outputted modulated signal from the myocardium, and at least one circuit to reduce the influence of process noise (aggressors) in the outputted modulated signal. The at least one circuit comprises an amplifier, a demodulator, and an integrator. The amplitude and phase of the final outputted modulated signal indicate the complex impedance of the myocardium. Changes in the complex impedance patterns of the myocardium provide indication of reduced oxygen and blood flow to the myocardium. The apparatus can be employed in implantable devices, including cardiac pacemakers and implantable cardioverter defibrillators.
摘要:
Methods of delivering optical stimulation to a target tissue from an optical stimulation device are provided. One method comprises sensing a temperature at the optical stimulation device or proximate to the optical stimulation device, and adjusting the delivery of light to the target tissue based on the sensed temperature. Another method comprises delivering the light to the target tissue with an optical light guide and sensing bioelectric signals with a sense electrode, wherein the optical light guide and the sense electrode each comprise a material that produces substantially no induced current in an electromagnetic field. Another method comprises delivering light from a light source of an optical stimulation device to a window of the optical stimulation device, delivering the light from the window to an optical light guide optically connected to the window, and delivering the light to a target tissue via the optical light guide.
摘要:
Seizure prediction systems and methods include measuring impedance and a potential within a brain of a patient to determine whether the brain is in a state indicative of a possibility of seizure. In some embodiments, at least one of the measured impedance or the measured potential may be used as a primary indication of the brain state indicative of a possibility of seizure. In one embodiment, if one of the measured impedance or the measured potential indicates a seizure, the other measurement (impedance or potential) may be used to validate whether the brain is in the state indicative of the possibility of seizure.
摘要:
This disclosure describes a chopper stabilized instrumentation amplifier. The amplifier is configured to achieve stable measurements at low frequency with very low power consumption. The instrumentation amplifier uses a differential architecture and a mixer amplifier to substantially eliminate noise and offset from an output signal produced by the amplifier. Dynamic limitations, i.e., glitching, that result from chopper stabilization at low power are substantially eliminated through a combination of chopping at low impedance nodes within the mixer amplifier and feedback. The signal path of the amplifier operates as a continuous time system, providing minimal aliasing of noise or external signals entering the signal pathway at the chop frequency or its harmonics. The amplifier can be used in a low power system, such as an implantable medical device, to provide a stable, low-noise output signal.
摘要:
In general, this disclosure is directed to a mixer amplifier that can be utilized within a chopper stabilized instrumentation amplifier. The chopper stabilized instrumentation amplifier may be used for physiological signal sensing, impedance sensing, telemetry or other test and measurement applications. In some examples, the mixer amplifier may include a current source configured to generate a modulated current at a modulation frequency for application to a load to produce an input signal, an amplifier configured to amplify the input signal to produce an amplified signal, and a demodulator configured to demodulate the amplified signal at the modulation frequency to produce an output signal indicating an impedance of the load.
摘要:
This disclosure describes a chopper stabilized instrumentation amplifier. The amplifier is configured to achieve stable measurements at low frequency with very low power consumption. The instrumentation amplifier uses a differential architecture and a mixer amplifier to substantially eliminate noise and offset from an output signal produced by the amplifier. Dynamic limitations, i.e., glitching, that result from chopper stabilization at low power are substantially eliminated through a combination of chopping at low impedance nodes within the mixer amplifier and feedback. The signal path of the amplifier operates as a continuous time system, providing minimal aliasing of noise or external signals entering the signal pathway at the chop frequency or its harmonics. The amplifier can be used in a low power system, such as an implantable medical device, to provide a stable, low-noise output signal.
摘要:
This disclosure describes a chopper stabilized instrumentation amplifier. The amplifier is configured to achieve stable measurements at low frequency with very low power consumption. The instrumentation amplifier uses a differential architecture and a mixer amplifier to substantially eliminate noise and offset from an output signal produced by the amplifier. Dynamic limitations, i.e., glitching, that result from chopper stabilization at low power are substantially eliminated through a combination of chopping at low impedance nodes within the mixer amplifier and feedback. The signal path of the amplifier operates as a continuous time system, providing minimal aliasing of noise or external signals entering the signal pathway at the chop frequency or its harmonics. The amplifier can be used in a low power system, such as an implantable medical device, to provide a stable, low-noise output signal.