Heart and lung monitoring with coherent signal dispersion
Inventors
Pratt, Thomas G. • Mueller, Jeffrey G. • Kossler, Robert D.
Assignees
Publication Number
US-12285246-B2
Publication Date
2025-04-29
Expiration Date
2035-11-09
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Abstract
Methods and systems for sensing a physiological characteristic of a subject. At least one receiver antenna can be provided in proximity to a portion of the subject's body to obtain at least one receiver signal resulting from at least one transmitter signal that has propagated to the receiver antenna and has been reflected, diffracted, scattered, or transmitted by or through the portion of the subject's body. One or more coherent signal pairs can be formed. Then, amplitude and phase information of a plurality of frequency components for each signal pair can be determined. A set of comparison values can be determined for each signal pair by comparing respective frequency component phases and respective frequency component amplitudes of the signals. Physiological characteristics of the subject can then be determined from these comparison values.
Core Innovation
The invention provides methods and systems for sensing physiological characteristics of a subject by employing at least one receiver antenna in proximity to a portion of the subject's body. Signals propagated from a transmitter and reflected, diffracted, scattered, or transmitted by or through this body portion are collected. One or more coherent signal pairs are formed from these signals, and amplitude and phase information for a plurality of frequency components within each signal pair are determined.
The amplitude and phase information of the frequency components for each signal pair is compared to obtain a set of comparison values. These comparison values are analyzed to derive physiological characteristics of the subject, such as heart or lung activity. In some embodiments, polarization information is determined through calculations using Jones vectors or Stokes parameters based on the comparison values for each frequency sub-band, providing enhanced sensing of physiological characteristics.
The problem addressed by this invention is the difficulty, impracticality, or inability of using contact-based monitoring devices for certain patients or situations, such as for combat medics treating casualties in the field, patients prone to removing monitors, or situations where attaching monitors is not feasible (e.g., neonatal or fetal heart monitors, inaccessible subjects). Previous monitoring devices require direct contact, while the disclosed method enables remote physiological sensing, even through clothing or common obstacles, using electromagnetic waves.
Claims Coverage
There are two independent claims: one directed to a method for sensing a physiological characteristic and one directed to a system for monitoring physiological characteristics. Each claim presents a core inventive feature.
Method for remote physiological sensing using coherent signal dispersion and polarization analysis
A method involving providing at least three antennas, including at least one transmitter and at least one receiver antenna, with at least one antenna comprising a pair of substantially orthogonally-polarized antennas. Signals, including at least one line of sight and one multipath signal reflected, diffracted, or scattered by or through the subject's body, are coherently obtained using synchronized clocks and local oscillators in a plurality of channels at both the transmitter and receiver. This coherence maintains phase information across a plurality of sub-bands, enabling accurate comparison of amplitude and phase information. The method further includes transforming the obtained signals into the frequency domain, analyzing amplitude and phase differences between received and corresponding transmitted signals, and calculating Jones vectors or Stokes parameters for the sub-bands. Polarization information derived from these calculations is used to characterize physiological characteristics of the subject.
System for physiological monitoring using coherent, polarization-sensitive signal processing
A system comprising at least three antennas, including at least one transmitter and at least one receiver antenna, with at least one antenna comprising a pair of substantially orthogonally-polarized antennas to enable characterization of combined line of sight and multipath signals based on their polarization states. The system includes a processor configured to coherently obtain signals (with synchronized clock and local oscillator on multiple channels at both transmitter and receiver), maintaining phase coherence across sub-bands. It determines amplitude and phase information for each obtained signal via frequency domain transformation, analyzes amplitude and phase differences between received and transmitted signals, calculates Jones vectors or Stokes parameters for sub-bands, and determines polarization information that characterizes physiological characteristics of the subject.
The claims cover both method and system aspects, focusing on coherent acquisition and analysis of polarization and signal dispersion to sense physiological characteristics remotely and non-invasively through amplitude and phase comparison and specialized polarization metrics.
Stated Advantages
Enables remote, non-contact physiological monitoring, removing the need for direct skin contact with the patient.
Allows operation through clothing and common obstacles, providing unobtrusive monitoring in varied environments such as homes, hospitals, and vehicles.
Able to monitor subjects that are difficult or impossible to monitor with contact-based devices, including in emergency, homecare, or neonatal/fetal scenarios.
Provides enhanced and diverse information through coherent signal dispersion and polarization analysis, facilitating the detection of various physiological states and anomalies.
Permits use of existing environmental signals (signals of opportunity), so operation does not always require a dedicated transmitter.
Supports integration into furniture or infrastructure, enabling continuous and convenient monitoring without user intervention.
Documented Applications
Remote monitoring of heart and lung activity, including heart rate, heart rhythm, blood pressure, arrhythmias, neontal and fetal heart rate, valve function, contractile/relaxation function, and lung respiration rate or volume.
Detection and monitoring of subject movement (e.g., head, limbs, torso), including live/dead assessment and sleep activity detection.
Blood pressure measurement using pulse transit time derived from RF responses at different body locations.
Differentiation between humans and animals based on physiological signatures such as heart rate.
Medical monitoring in environments where contact-based devices are impractical, such as battlefield casualty triage or homecare for patients prone to removing monitors.
Integration into beds, chairs, walls, or vehicles for unobtrusive physiologic monitoring in residential, clinical, or transportation settings.
Use in research and diagnostics, including animal studies (e.g., heart and lung activity in mice or sheep), arrhythmia and pacemaker monitoring, and deep learning analysis to detect physiological or anatomical anomalies.
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