Abstract: A capacitive sensing system is adapted for noninvasive measurement of blood pulse (hear rate). A capacitive sensor is located near a skin pulse point exhibiting pulse displacement of skin tissue from vascular pulsation (for example, the temple area of the head), and includes a sensor electrode disposed over and spaced from the skin pulse point, such that the distance between sensor electrode and the skin pulse point cycles between a proximal and a distal displacement distance based on vascular pulsation.

Abstract: An inductive sensing system includes multiple resonant sensors interfaced to an inductance-to-digital conversion (IDC) unit through a single channel interface. IDC establishes an IDC control loop that incorporates resonant sensors as loop filters. The IDC control loop drives resonant sensors to a system resonance state in which each resonant sensor is driven to a resonant frequency state. Each resonant sensor is configured for a nominal resonant frequency state that differentiates it from the other resonant sensors. IDC senses changes in system resonance state representative of target-sensing conditions, and responds by driving a target-sensing system resonance state. IDC converts IDC loop (resonance) control signals resulting from a target-sensing condition into sensor data as representing the corresponding target-sensing resonant frequency state as an indication of target position (proximity or range) relative to a target-sensing resonant sensor.

Abstract: An inductive sensing system includes multiple resonant sensors interfaced to an inductance-to-digital conversion (IDC) unit through a single channel interface. IDC establishes an IDC control loop that incorporates resonant sensors as loop filters. The IDC control loop drives resonant sensors to a system resonance state in which each resonant sensor is driven to a resonant frequency state. Each resonant sensor is configured for a nominal resonant frequency state that differentiates it from the other resonant sensors. IDC senses changes in system resonance state representative of target-sensing conditions, and responds by driving a target-sensing system resonance state. IDC converts IDC loop (resonance) control signals resulting from a target-sensing condition into sensor data as representing the corresponding target-sensing resonant frequency state as an indication of target position (proximity or range) relative to a target-sensing resonant sensor.

Abstract: A capacitive sensing system is adapted for noninvasive measurement of blood pulse (hear rate). A capacitive sensor is located near a skin pulse point exhibiting pulse displacement of skin tissue from vascular pulsation (for example, the temple area of the head), and includes a sensor electrode disposed over and spaced from the skin pulse point, such that the distance between sensor electrode and the skin pulse point cycles between a proximal and a distal displacement distance based on vascular pulsation.

Abstract: An inductive sensing system is adapted for noninvasive measurement of blood flow through a blood vessel. A resonant sensor is disposed in proximity to the blood vessel, and includes a coil resonator that generates a magnetic field within a sensing area that includes the blood vessel. The resonator changes resonance state based on changes in a flow of blood hemoglobin through the sensing area. The IDC unit establishes an IDC control loop, including the resonator as a loop filter, that provides feedback resonance control of the resonator to maintain a resonant frequency state (steady state oscillation) representative of blood hemoglobin flow through the sensing area. A feedback resonance control signal provides sensor data corresponding to the resonant frequency state as representative of blood flow through the sensing area. In one embodiment, the IDC control loop is implemented as a negative impedance control loop, controlling negative impedance to counterbalance resonant impedance.