BLOOD PULSE MEASUREMENT BASED ON CAPACITIVE SENSING

摘要

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. A capacitance-to-digital conversion (CDC) unit includes excitation circuitry providing sensor excitation to generate a sensor E-field between the sensor electrode and the skin pulse point based on sensor self-capacitance, and capacitance acquisition/conversion circuitry that acquires capacitance measurements for proximal and distal self-capacitance (for example, by multi-phase capacitive charge transfer using a switched capacitor arrangement), and converts these capacitance measurements into sensor data representative of vascular pulsation.

主权项

1. A capacitive sensing system adapted for noninvasive measurement of pulsation of a blood vessel within a body, comprising:
a capacitive sensor disposed external to the body in proximity to a skin pulse point exhibiting pulse displacement of skin tissue caused by pulsation of the blood vessel (vascular pulsation); the capacitive sensor including:
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 distance based on vascular pulsation, where the proximal distance corresponds to a proximal pulse displacement, and the distal distance corresponds to a distal pulse displacement; anda sensor shield disposed over and insulated from the sensor electrode; a capacitance-to-digital conversion (CDC) unit coupled to the capacitive sensor, and configured to convert sensor capacitance into sensor data representative of the vascular pulsation, including:
excitation circuitry configured to:
provide sensor excitation to excite the sensor electrode, generating a sensor E-field between the sensor electrode and the skin pulse point based on sensor self-capacitance; andprovide shield drive to drive the sensor shield to generate a shield E-field such that the sensor E-field is concentrated in the direction of the skin pulse point; andcapacitance acquisition/conversion circuitry configured to:
acquire capacitance measurements for a proximal self-capacitance of the sensor electrode with the skin pulse point at proximal displacement, and a distal self-capacitance of the sensor electrode with the skin pulse point at distal displacement; andconvert the proximal and distal self-capacitance measurements into sensor data representative of vascular pulsation.