US 11,596,320 B2 · Blood pulse measurement based on capacitive sensing

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. 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.

Claims22

Dependent claims

A method comprising:

determining a first capacitance at a first distance between skin and a surface of a capacitive sensor, in which the surface is spaced a first distance from the skin, the determining of the first capacitance including exciting an electrode of the capacitive sensor to charge the capacitive sensor and to generate an electric field between the electrode and the skin based on self-capacitance;
determining a second capacitance at a second distance between the skin and the surface of the capacitive sensor, the second distance being greater than the first distance, the determining of the second capacitance including exciting the electrode to charge the capacitive sensor and to generate an electric field between the electrode and the skin based on self-capacitance, the first and second capacitances representing vascular pulsation of a blood vessel at a pulse point;
and
converting the first and second capacitances into data representing the vascular pulsation.

1 more element

A system comprising:

a capacitive sensor including an electrode;
excitation circuitry coupled to the capacitive sensor and configured to provide excitation and shield drive signals to the capacitive sensor;
a multiplexer having inputs coupled to the electrode;
a capacitive-to-digital converter coupled to an output of the multiplexer, the capacitive-to-digital converter configured to:
determine a first capacitance sensed at a first distance between a surface of the electrode and skin;
and
determine a second capacitance sensed at a second distance between the surface of the electrode and the skin, the first and second capacitances representing vascular pulsation of a blood vessel at a pulse point;
and
convert the first and second capacitances into digital data representing the vascular pulsation;
wherein, in determining each of the first and second capacitances, the capacitive-to-digital converter is further configured to excite the electrode to charge the capacitive sensor and generate an electric field between the electrode and the skin based on self-capacitance.

7 more elements

Dependencies are inferred from the claim text.

Blood pulse measurement based on capacitive sensing

Life of this patent

Blood pulse measurement based on capacitive sensing

Life of this patent

Abstract

Claims22