Abstract: The present invention provides a device and method to efficiently turn light from an optical fiber around a corner while avoiding the frustrated-TIR loss that would occur if the fiber were bent. The invention uses non-imaging optics which efficiently deal with beam divergence half-angles less than 90°. By recognizing that most light from a fiber optic source will have a divergence half-angle of less than 90 degrees, a practical solution is achieved using non-imaging optics.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a sensor, comprising a light emitting element configured to emit light, a light detecting element configured to detect the light, and a memory storing data corresponding to algorithms used by an oximeter monitor, the memory providing access to the oximeter monitor to read the data.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a method of sensor operation, comprising emitting light from a light emitting element of the sensor, detecting the light with a light detecting element of the sensor, storing sensor model identification data within a memory of the sensor, and providing access to the memory to facilitate reading the sensor model identification data with an oximeter monitor.

Abstract: A light emitter drive circuit for an oximeter which utilizes a single inductor for driving multiple light emitters. The inductor is connected to a switching circuit to multiple energy storage circuits, such as capacitors. These are alternately charged up, using the same inductor. Subsequently, the capacitors are alternately discharged for their corresponding light emitters through the same inductor. Also, the magnetic susceptibility of the LED drive circuit is reduced by using magnetic flux canceling in the inductor. In one embodiment, a toroidal inductor is used with geometric symmetry and its magnetic flux. In another embodiment, a dual core closed bobbin shielded inductor is used.

Abstract: An apparatus and method for determining if a forward voltage of an LED in a pulse oximeter is within a predetermined range. This is accomplished by measuring the current through the LED, and also by knowing the duty cycle of the pulse width modulator (PWM) drive signal to the LED.

Abstract: Embodiments of the present invention relate to a sensor for facilitating detection of a physiological characteristic of a patient. Specifically, one embodiment includes a detector configured to obtain signals from the patient, the signals being indicative of the physiological characteristic and to send the signals to a monitor, and a sensor memory coupled with the sensor and separate from the monitor, the sensor memory storing patient physiological data derived by the monitor from the signals, the patient physiological data being indicative of the physiological characteristic.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a sensor comprising a light emitting element configured to emit light, a light detecting element configured to detect the light, and a memory storing a manufacturer identification, the memory providing access to an oximeter monitor to read the manufacturer identification.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a method of sensor operation, comprising a light emitting element configured to emit light, a light detecting element configured to detect the light, and a memory storing a language code or country code, the memory providing access to an oximeter monitor to read the language code or country code.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a sensor comprising a light emitting element configured to emit light, a light detecting element configured to detect the light, and a memory storing at least one patient-specific parameter, the memory providing access to an oximeter monitor to read the at least one patient-specific parameter.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a method of sensor operation, comprising emitting light from a light emitting element of the sensor, detecting the light with a light detecting element of the sensor, and providing a manufacturer identification of the sensor stored within a memory of the sensor to an oximeter monitor.

Abstract: Embodiments of the present invention include systems and methods that relate to a sensor with memory. Specifically, one embodiment includes a sensor comprising a light emitting element configured to emit light, a light detecting element configured to detect the light, and a memory storing sensor model identification data, the memory providing access to an oximeter monitor to read the sensor model identification data.

Abstract: A method and apparatus for the application of Blind Source Separation (BSS), specifically independent Component Analysis (ICA) to mixture signals obtained by a pulse oximeter sensor. In pulse oximetry, the signals measured at different wavelengths represent the mixture signals, while the plethysmographic signal, motion artifact, respiratory artifact and instrumental noise represent the source components. The BSS is carried out by a two-step method including an ICA. In the first step, the method uses Principal Component Analysis (PCA) as a preprocessing step, and the Principal Components are then used to derive sat and the Independent Components, where the Independent Components are determined in a second step. In one embodiment, the independent components are obtained by high-order decorrelation of the principal components, achieved by maximizing the sum of the squares of the higher-order cumulants of the plurality of mixture signals.

Abstract: A pulse oximeter with drive lines for driving red and IR LEDs, and a drive circuit for driving those drive lines. A processor controls the drive circuit using a red zero output line and an IR zero output line directly connected between the processor and the drive circuit. This allows a control signal to directly control the turning off of either the red or IR drive transistors to prevent forward current flow through the red and IR LEDs by overriding the ongoing programmable logic state machine control of the drive transistors. The effects of crosstalk and capacitive coupling are reduced as a result.

Abstract: A method and apparatus for reducing cross-talk in an oximeter. The oximeter includes a band pass filter. The amount of cross-talk through the band pass filter is estimated. Based on this estimate, the corner frequencies of the band pass filter are adjusted when it is designed to minimize the cross-talk. In one embodiment, a calibration mode is performed when a sensor is attached to the oximeter. In the calibration mode, the signals are measured with first only the red LED on and then with only the IR LED on. Any signal measured in the off channel is assumed to be a result of cross-talk from the other channel. The magnitude of the cross-talk is determined as a percentage, and subsequently the percentage is multiplied by the actual signal and subtracted from the other LED signal as cross-talk compensation.

Abstract: A light emitter drive circuit for an oximeter which utilizes a single inductor for driving multiple light emitters. The inductor is connected to a switching circuit to multiple energy storage circuits, such as capacitors. These are alternately charged up, using the same inductor. Subsequently, the capacitors are alternately discharged for their corresponding light emitters through the same inductor. Also, the magnetic susceptibility of the LED drive circuit is reduced by using magnetic flux canceling in the inductor. In one embodiment, a toroidal inductor is used with geometric symmetry and its magnetic flux. In another embodiment, a dual core closed bobbin shielded inductor is used.

Abstract: An oximeter uses a sigma-delta modulator and a multi-bit ADC with PWM feedback enabling high precision multi-bit conversion. Demodulation is done in software, thus requiring only a single hardware path for both red and IR. Multiple capacitors are switched into the integrator in the sigma-delta modulator, with different capacitors for red, IR and dark signals, thus enabling the use of the single hardware path. A switching circuit at the input of the sigma-delta modulator acts as a sample and hold, controlled by the PWM feedback.

Abstract: An apparatus and method for determining if a forward voltage of an LED in a pulse oximeter is within a predetermined range. This is accomplished by measuring the current through the LED, and also by knowing the duty cycle of the pulse width modulator (PWM) drive signal to the LED.

Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.

Abstract: A method and apparatus for providing a substantially real-time representation of an analog representation of a physiological signal. The waveform signal from the sensor is converted into digital form. A delta-sigma modulator is used as a simple Digital-to-analog Converter (ADC). The output can then be provided through a simple hardware filter to give an analog output signal in nearly real-time, which can be used for other instruments, synchronization, display, etc.

Abstract: A method for use and an improved oximeter sensor substrate that is conforming to the shape of the patient's forehead. In one embodiment, the present invention is an oximeter sensor, having a substrate with a shape similar to a shape of at least a portion of a patient's forehead and including a section adapted to substantially fit over a portion of a forehead of a patient; an emitter disposed on the substrate at a position located on the section; and a detector disposed on the substrate at a distance from the emitter. In one embodiment, the substrate includes a hat that holds the emitter and the detector in a spaced-part manner against the patient's forehead.