Remote non-contact device, system, and method for maternal / fetal physiological activity monitoring

Abstract

A non-contact maternal / fetal physiological activity monitoring system includes a radar sensor (e.g., mm-wave radar emitter and receiver) and a signal processor configured to select at least one pair of range and angle coordinates of a received radar signal, and for each range and angle coordinate pair: generate a selected heart activity signal, perform high-pass or bandpass filtering, and process a filtered heart activity signal to generate an estimated heart rate signal and audio signal (including a cardiac acoustic signal). Heart rate and audio signals may be generated for maternal, fetal, or both maternal and fetal subjects.

Description

REMOTE NON-CONTACT DEVICE, SYSTEM, AND METHOD FOR MATERNAL / FETAL PHYSIOLOGICAL ACTIVITY MONITORINGCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 581 ,322 filed on September 8, 2023, wherein the entire contents of the foregoing application are hereby incorporated by reference herein.BACKGROUND

[0002] Fetal heart rate monitoring is a procedure used to evaluate the well-being of a fetus by assessing the rate and rhythm of the fetal heartbeat. During late pregnancy and labor, physicians recommend monitoring fetal heart rate and other functions. As a fetus responds to conditions in the uterus, the fetal heart rate can vary. The average fetal heart rate is between 110 and 160 beats per minute, and can vary by 5 to 25 beats per minute. An abnormal fetal heart rate or pattern may indicate that the fetus is not getting sufficient oxygen and / or that other problems may exist.

[0003] Current non-invasive methods use a device to listen to or record a fetal heartbeat through a mother’s abdomen. A fetoscope (i.e., a type of stethoscope) is the most basic type of external fetal heart rate monitor. Other types of monitors utilize Doppler ultrasound-based technologies or microphone I accelerator sensor technologies. The foregoing types of monitors utilize contact-based methods, and signals obtained therefrom are subject to being degraded by surrounding noise. Moreover, these monitors and monitoring methods require physical maneuvering to locate the fetal heartbeat, which can be challenging at times.

[0004] Additionally, maternal vital signs, such as heart rate and respiratory rate, provide critical insight into an expectant mother’s well-being. Traditional methods of vital sign monitoring involve inconvenient and uncomfortable wearable devices. To capture both heart and respiratory rates, two different sensors are required, e.g., a multi-LED electrocardiography sensor which measures the heart’s electrical activity and a chest respiration belt which measures the air pressure variation according to the breathing of the subject. More convenient means of non-contact monitoring are then required to address these needs.SUMMARY

[0005] A radar-based non-contact system and method for maternal I fetal physiological activity monitoring is provided. A non-contact maternal / fetal physiological activity monitoring system includes a radar sensor (e.g., millimeter-wave radar emitter and receiver) and a signal processor configured to perform multiple functions, such as to acquire and measure prenatal heartbeat sound and measure the rate and rhythm variability of at least one fetal heartbeat. The system and method operate through regular layers of clothing / blankets, thereby providing privacy and convenience. Additionally, vital information of the expectant mother, such as respiration and heart sound, can be obtained in captured radar echoes reflected from various body parts of the mother, wherein maternal and fetal information (or fetal-fetal information in the case of multiple fetuses in gestation) can be separated through radar beam steering operation.

[0006] One function includes receiving a radar signal from the radar sensor. Another function includes selecting at least one pair of range and angle coordinates of the received radar signal and, for each selected pair of angle and range coordinates, generating a selected heart activity signal associated with the selected pair of range and angle coordinates. Another function includes, for each selected pair of range and angle coordinates, filtering the selected heart activity signal utilizing a high-pass or bandpass filtering scheme to generate a filtered heart activity signal. Another function includes, for each selected pair of range and angle coordinates, processing the filtered heart activity signal to generate an estimated heart rate signal and an audio signal including a cardiac acoustic signal.

[0007] In one aspect, the disclosure relates to a non-contact maternal / fetal physiological activity monitoring system, comprising: a radar sensor configured to be positioned in a signal-receiving range separated apart from a pregnant female subject; and a signal processor configured to: receive a radar signal from the radar sensor; select at least one pair of range and angle coordinates of the received radar signal and, for each selected pair of angle and range coordinates, generating a selected heart activity signal associated with the selected pair of range and angle coordinates; for eachselected pair of range and angle coordinates, filter the selected heart activity signal utilizing a high-pass or bandpass filtering scheme to generate a filtered heart activity signal; and for each selected pair of range and angle coordinates, process the filtered heart activity signal to generate an estimated heart rate signal and an audio signal including a cardiac acoustic signal.

[0008] In certain embodiments, the at least one selected heart activity signal corresponds to a fetal heart activity signal, the estimated heart rate signal comprises a fetal heart rate signal, and the cardiac acoustic signal comprises a fetal cardiac acoustic signal

[0009] In certain embodiments, the at least one selected heart activity signal corresponds to a maternal heart activity signal, the estimated heart rate signal comprises a maternal heart rate signal, and the cardiac acoustic signal comprises a maternal cardiac acoustic signal

[0010] In certain embodiments, the at least one pair of angle and range coordinates selected by the signal processor comprises a first pair of angle and range coordinates corresponding to a fetal heart activity signal, and comprises a second pair of angle and range coordinates corresponding to a maternal heart activity signal.

[0011] In certain embodiments, the at least one pair of angle and range coordinates selected by the signal processor comprises a first pair of angle and range coordinates corresponding to a first fetal heart activity signal, and comprises a second pair of angle and range coordinates corresponding to a second fetal heart activity signal.

[0012] In certain embodiments, the signal processor is further configured to perform clutter mitigation on the received radar signal.

[0013] In certain embodiments, the radar signal comprises a millimeter-wave radar signal.

[0014] In another aspect, the disclosure relates to a non-contact method for maternal / fetal physiological activity monitoring, the method comprising: receiving, by a radar sensor, a radar signal comprising a reflection of an emitted radar signal impinged on a pregnant female subject; selecting, by a signal processor, at least one pair of range and angle coordinates of the received radar signal, and, for each selected pair of angle and range coordinates; generating, by the signal processor, a selected heart activitysignal associated with each selected pair of range and angle coordinates; for each selected pair of range and angle coordinates, filtering, by the signal processor, the selected heart activity signal utilizing a high-pass or bandpass filtering scheme to generate a filtered heart activity signal; and for each selected pair of range and angle coordinates, processing, by the signal processor, the filtered heart activity signal to generate an estimated heart rate signal and an audio signal including a cardiac acoustic signal.

[0015] In another aspects, any of the foregoing aspects may be combined with one another, and / or combined with or more elements or features described herein for additional advantage.BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0017] FIG. 1 is a schematic illustration of a non-contact radar-based maternal I fetal physiological activity monitoring system including radar transmit / receive and signal processing components arranged proximate to a pregnant female subject (i.e., an expectant mother).

[0018] FIG. 2 is a first block diagram showing a processing chain utilized by a noncontact radar-based maternal I fetal physiological activity monitoring system according to one embodiment of the present disclosure.

[0019] FIG. 3 is a second block diagram showing a processing chain utilized by a non-contact radar-based maternal / fetal physiological activity monitoring system according to one embodiment of the present disclosure.

[0020] FIG. 4 is a front view of an orthogonal antenna system having two linear, orthogonally-oriented phased array antennas as part of a non-contact radar-based maternal I fetal physiological activity monitoring system according to one embodiment of the present disclosure.

[0021] FIG. 5 is a plot of maternal breathing pattern (in amplitude versus time) obtained from a non-contact radar-based maternal / fetal physiological activity monitoring system according to one embodiment.

[0022] FIGS. 6A and 6B are frequency response diagrams (in frequency versus time) for maternal heart sound and fetal heart sound, respectively, obtained from the same non-contact radar-based maternal I fetal physiological activity monitoring system used to obtain the maternal breathing plot of FIG. 5.

[0023] FIG. 7A is a frequency response diagram (in frequency versus time) for fetal heart sound obtained from a non-contact radar-based maternal / fetal physiological activity monitoring system as disclosed herein.

[0024] FIG. 7B is a frequency response diagram (in frequency versus time) for fetal heart sound obtained from a conventional contact-based ultrasound device, to provide a basis for comparison to FIG. 7A.

[0025] FIG. 8A is a plot of spectrum power versus beats / minute derived from a noncontact radar-based maternal / fetal physiological activity monitoring system as disclosed herein.

[0026] FIG. 8B is a plot of spectrum power versus beats / minute derived from a conventional contact-based ultrasound device, to provide a basis for comparison to FIG. 8A.

[0027] FIG. 9 is a block diagram including components of a radar-based maternal / fetal physiological activity monitoring system 10 according to embodiments disclosed herein.DETAILED DESCRIPTION

[0028] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

[0029] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0030] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0031] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0034] A radar-based non-contact system and method for maternal / fetal physiological activity monitoring is provided. A non-contact maternal / fetal physiological activity monitoring system includes a radar sensor (e.g., millimeter-wave radar emitter and receiver) and a signal processor configured to perform multiple functions, such as to acquire and measure prenatal heartbeat sound and measure the rate and rhythm variability of at least one fetal heartbeat. The system and method operate through regular layers of clothing / blankets, thereby providing privacy and convenience. Additionally, vital information of the expectant mother, such as respiration and heart sound, can be obtained in captured radar echoes reflected from various body parts of the mother, wherein maternal and fetal information can be separated through radar beam steering operation.

[0035] FIG. 1 is schematic illustration of a non-contact radar-based maternal / fetal physiological activity monitoring system 12 according to embodiments described herein, arranged proximate to a pregnant female subject 14. The radar-based maternal I fetal physiological activity monitoring system 12 provides a non-contact approach to measuring acoustic features of the subject 14 and an associated fetus (not shown). Such acoustic features may include maternal cardiac and respiratory acoustic features, and fetal acoustic features., The radar-based maternal I fetal physiological activity monitoring system 12 includes a radar sensor 16 (e.g., an ultra-wide band (UWB) radar sensor, optionally including one or more multiple arrays) to remotely measure acoustic features of vital signs of the pregnant female subject 14 (obtained by processing reflected radar signals received from the subject’s chest 10) and / or an associated fetus (obtained by processing reflected radar signals received from the subject’s abdomen 11 ). The radar-based maternal / fetal physiological activity monitoring system 12 also includes a signal processor 18 which processes radar signals received by the radar sensor 16 to extract acoustic features, such as acoustic features associated with respiratory and cardiac activity of the pregnant female subject 14, and cardiac activity of the fetus. Vital signs such as heart rate, heart rhythm variability, and / or respiratory rate may also be determined.

[0036] In an exemplary aspect, the radar sensor 16 is coupled to the signal processor 18, which processes a radar return (Rx) signal 22 (including return signalportions 22A, 22B) received by the radar sensor 16. One radar return signal portion 22A carries acoustic information corresponding to the maternal subject 14 (e.g., reflected from the subject’s chest 10), and another radar return signal portion 22B carries acoustic information corresponding to an associated fetus (e.g., reflected from the subject’s abdomen 11 ), and the signal processor 18 extracts therefrom one or more acoustic features of the subject 14 and / or associated fetus.

[0037] The radar sensor 16 includes a radar receiver 24 to receive the radar return signal portions 22A, 22B and may further include a radar transmitter 26 which emits a radar signal 20 (including transmitted portions 20A, 20B). The radar sensor 16 (via the receiver 24) can receive a radar return signal 22 (including return portions 22A, 22B) in any RF band, such as terrestrial radio frequencies, gigahertz (GHz) bands, terahertz bands, microwave bands, etc. The radar return signal 22 can be a reflection of radar signal 20 emitted by the radar transmitter 26 as reflected from tissues of the subject 14. The emitted radar signal 20 may penetrate a portion of the skin of the subject 14 (and fetus therein) before reflecting back to the radar sensor 16. In some examples, the radar sensor 16 operates on a frequency-modulated continuous-wave (FMCW) signaling scheme with a wide bandwidth in the millimeter or terahertz RF bands. In various embodiments, the radar transmitter 26 can transmit the emitted radar signal 20 at predefined intervals over a period of time. The radar receiver 24 can receive a plurality of reflected radar return signals 22, where each radar return signal 22 can correspond to a respective emitted radar signal 20 (e.g., return signal 22A may correspond to emitted signal 20A, and return signal 22B may correspond to emitted signal 20B). The signal processor 18 can identify acoustic data by analyzing the radar return signals 22A, 22B, in particular, by processing the radar return signals by comparing phase differences between respective radar return signals 22A, 22B which can indicate movement of the subject 14 and / or fetus, and in particular, movement caused by vibrations associated with heart sounds or respiratory sounds caused by the lungs or other portion of the subject 14, or vibrations associated with heart sounds of the fetus. Based on the frequency band of the radar return signal 22A, 22B, the amount and frequency of occurrence of the phase differences (indicating magnitude and frequencyof acoustic sound) the signal processor 18 can identify acoustic features and vital signs from the radar return signals 22A, 22B.

[0038] In certain embodiments, the radar transmitter 26 may be fixated for monitoring, and / or may be handheld for screening. If desired, the radar transmitter 26 may be selectively utilized in a fixated or handheld state.

[0039] In an embodiment, the radar transmitter 26 can transmit the radar signals 20A, 20B at predefined frequencies and / or bands based on the type of acoustic signal (e.g., acoustic signal relating to vital sign(s)) desired to be extracted. The radar transmitter 26 can also alternate the frequency and / or band according to some predefined pattern (e.g., sequentially) to capture acoustic data associated with different sources.

[0040] In certain embodiments, multiple radar transmitters may be provided in an array, and multiple radar receivers may be arranged in an array. In one embodiment, a radar transmitter array may comprise a first linear array, a radar receiver array may comprise a second linear array, and the first and second arrays may be non-parallel (e.g., orthogonal) relative to one another. In certain embodiments, a radar transmitter array may include individual transmitters arranged in a horizontal line and a radar receiver array may include individual receivers arranged in a vertical line, or vice-versa. Numerous positional variations may be employed to form virtual array elements arranged in a two-dimensional configuration, so long as the transmitter and receiver arrays are not arranged parallel to one another.

[0041] In an embodiment, a non-contact radar-based maternal / fetal physiological activity monitoring system can be an FMCW radar system using a sawtooth waveform as the transmitting signal is utilized. The signal is analytically expressed as:

[0043] where a = B / Tcis the slope rate of the frequency sweep, f0is the starting frequency, T is the fast time e [0Tc] , and t is the slow time. The backscattered at the radar receiver for one chirp frame is expressed as:

[0045] where d(t) is the time-varying physical displacement and A(t) is a complex amplitude, encapsulating the channel effects and target response. Usually, the signalprocessing is done after mixing in complex baseband. For MIMO FMCW radar with multiple Tx and Rx antennas under far-field assumption, the time delay among the array elements is simplified as a phase difference along the incident angle in the baseband signal. For a uniform linear virtual array, the baseband signal of MIMO FMCW radar at the Ithelement is expressed as:

[0047] where 0 is the incident angle and d is the antenna spacing. The body displacement is extracted in the phase of the beat signal.

[0048] A multi-beam operation is applied to isolate the desired target at the incident angle 0 from other targets located at different angles. By combining multiple spatial channels, the signal quality is improved. The beam-steering vector w is given as:

[0050] where N is the size of the MIMO virtual array. The output of the virtual array is:

[0051] s = | .s' , ], ..., sw]TEqn. 5

[0052] The beamformer output is given by the inner product of Eqn. (4) and Eqn. (5),

[0054] The modulated phase of the beat signal contains the signal of interest. Fast- time FFT is first invoked over each chirp frame. The FFT results of Eqn. (6) is expressed as:

[0055] sine { 5 [v> vr] , Eqn. 7

[0056] where v, representing range profile, is the Fourier component with respect toT. The maximum signal response is obtained at the target range bin, vT. Eqn. (7) is then simplified as,

[0058] The phase variation due to human vocal motion and chest motion can be estimated from Eqn. 8.

[0059] Like many other natural signals, physiological signals are time-varying and non-stationary. In this study, time frequency analysis is implemented using short-time- Fourier Transform (STFT) to reveal meaningful time-varying signatures. The STFT is defined as:

[0061] Where p(t) is the extracted phase signal and w(t) is a non-zero window function. The window length has to approximately match the time scale of the analyzed signal.

[0062] The STFT spectrogram from the same data exhibits the distinctive spectral features of the radar vocal sound and radar heart sound. Energy clusters below 100 Hz are mainly related to heart sound while the ones above 100 Hz are mainly related to vocal sound. Radar heart sound signal power is about 15 dB stronger than that of radar vocal sound. Additionally, the instantaneous frequency of the two signals behave differently with time. Radar heart sound shows up as a train of bursts that are low in frequency and short in time. On the other hand, radar vocal sound is relatively high in frequency and expanded in time. Based on this observation, radar vocal sound and radar heart sound can be separated through spectral filtering for enhanced identification. An exemplary scheme may incorporate radar processing, including subject detection, beamforming, range FFT and phase extraction. Bandpass filtering may be applied to separate radar vocal sound and heart sound based on their spectral signatures. A wavelet based denoising algorithm may be implemented using 1-D discrete stationary wavelet transform (SWT) with a soft thresholding for denoising. The SWT decomposition during the analysis phase of the filtered radar signals results in a denoised radar vocal sound and radar heart sound have an enhanced signal quality. The developed signal processing chain improves the radar vocal sound signal-to-noise ratio (SNR) and thus the traces of the 2nd and 3rd-order harmonics of the fundamental vocal sound are recovered in the spectrogram. Similarly, the SNR improvement is found in the denoised radar heart sound.

[0063] FIG. 2 is a first block diagram 130 showing a processing chain utilized by a non-contact radar-based maternal / fetal physiological activity monitoring system according to one embodiment of the present disclosure, the processing chain includingmultiple functional blocks or steps. A data acquisition step 132 includes reception of a radar signal. Following data acquisition, signal processing of the acquired signal (which may include components received from a mother and one or more fetuses) is performed according to multiple steps. For example, signal processing includes a range / angle selection (optionally combined with clutter mitigation) step 134. Clutter refers to the received echoes from environmental scatterers other than the targets. In certain embodiments, the clutter mitigation exploits the relatively high Doppler frequencies of moving targets to suppress clutter echoes (from stationary items), which usually have zero or very low Doppler frequencies. As one result of the range / angle selection step 134, a first or main signal 135 is obtained corresponding to fetal cardiac acoustics, received from a reflected radar signal returned from an expectant mother’s abdomen (11 in FIG. 1 ). In certain embodiments, a fetal heart acoustic filtering step 136 including high-pass or band-pass filtering is performed to extract the energy distribution at the fundamental heart acoustic band in a desired frequency range (e.g., 20 Hz - 80 Hz) corresponding to maternal cardiac activity. A fetal heart rate signal processing step 137 includes processing of this first or main signal to quantify fetal heart rate and heart rhythm variability. A fetal heart audio processing step 138 includes generation of one or more processed audio signals corresponding to fetal cardiac activity, wherein such processed audio signals may also be generated (output / stored), monitored, played, and / or heard. As another result of the range / angle selection step 134, a second (e g., secondary) signal 146 is obtained corresponding to maternal cardiac and / or respiratory acoustics, received from a reflected radar signal returned from an expectant mother’s chest (10 in FIG. 1). This second signal 146 may be processed according to a maternal vital sign processing step 146 to determine (e.g., quantify) maternal heart rate and heart rhythm variability and provide output signals thereof. In certain embodiments, the maternal vital sign processing step 146 may include determining maternal respiratory rate (and respiratory activity) and providing output signals thereof. In certain embodiments, the maternal vital sign processing step 146 may include generating processed audio signals corresponding to maternal cardiac activity and / or maternal respiratory activity, wherein such processed audio signals may also be generated (output / stored), monitored, played, and / or heard.

[0064] FIG. 3 is a second block diagram 150 showing a processing chain utilized by a non-contact radar-based maternal / fetal physiological activity monitoring system according to one embodiment of the present disclosure, the processing chain including multiple functional blocks or steps. A data acquisition step 152 includes reception of a radar signal. Following data acquisition, signal processing of the acquired signal (which may include components received from a mother and one or more fetuses) is performed according to multiple steps. For example, signal processing includes a range / angle selection (optionally combined with clutter mitigation) step 154. In certain embodiments, multiple acoustic filtering steps 156, 166, 176 are employed. A maternal heart acoustic filtering step 156 (e.g., high-pass or band-pass filtering, optionally configured to pass signals in a range of 20-80 Hz or a subrange thereof) is performed to extract the energy distribution at the fundamental heart acoustic band in a desired frequency range corresponding to a maternal heart. A maternal heart rate signal processing step 157 utilizes the filtered signal resulting from step 156 to provide output signals such as maternal heart rate (optionally in conjunction with maternal heart rate variability), and a maternal heart audio processing step 158 utilizes the filtered signal resulting from step 156 to provide audio outputs corresponding to maternal heart sound, wherein such audio signals may also be generated (output I stored), monitored, played, and / or heard. A maternal respiratory acoustic signal filtering step 166 (e.g., high-pass or band-pass filtering, optionally configured to pass signals in a range of 0.4-1 .5 Hz or a subrange thereof) is performed to extract the energy distribution at the fundamental respiratory acoustic band in a desired frequency range corresponding to maternal respiration. A maternal respiratory signal processing step 167 processes the filtered signal resulting from step 166 to provide output signals such as maternal respiration rate and maternal respiration variability. A maternal audio signal processing step 168 processes the filtered signal resulting from step 166 to provide audio signals corresponding to maternal respiratory activity, wherein such audio signals may also be generated (output / stored), monitored, played, and / or heard. A fetal heart acoustic filtering step 176 (e.g., high-pass or band-pass filtering, optionally configured to pass signals in a range of 20- 80 Hz or a subrange thereof) is performed to extract the energy distribution at the fundamental heart acoustic band in a desired frequency range corresponding to a fetalheart. A fetal heart rate signal processing step 177 utilizes the filtered signal resulting from step 176 to provide output signals such as fetal heart rate (optionally in conjunction with maternal heart rate variability), and a fetal audio processing step 178 utilizes the filtered signal resulting from step 176 to provide audio outputs corresponding to fetal heart sound, wherein such audio signals may also be generated (output I stored), monitored, played, and / or heard.

[0065] FIG. 4 is a front view of an orthogonal antenna system having two linear, orthogonally-oriented phased array antennas 120, 122 as part of a non-contact radarbased maternal I fetal physiological activity monitoring system according to one embodiment of the present disclosure. In one embodiment, a first array antenna 120 comprises a transmit antenna array including multiple linearly arranged radar transmitters 120-1 to 120-X, while a second array antenna 122 comprises a receiver antenna array including multiple linearly arranged radar receivers 122-1 to 122-X.Given the L-shapes composite array (with transmitters 120-1 to 120-X and receiver 122- 1 to 122-X positioned in linear arrays that are orthogonal to one another) in FIG. 4C, the angular resolution in the x-axis and the y-axis may be the same. Virtual elements may be assigned transmit / receive pairs, In certain embodiments, each array antenna 120, 122 may comprise arrayed transceivers that provide both transmit and receive functionality.

[0066] FIG. 5 is a plot of maternal breathing pattern (in amplitude versus time) obtained from a mmWave non-contact radar-based maternal / fetal physiological activity monitoring system according to one implementation. As shown, each cycle of amplitude variation occurs over a period of about 5 seconds, according to a relatively consistent temporal pattern and waveform shape.

[0067] FIGS. 6A and 6B are frequency response diagrams (in frequency [Hz] versus time [s]) for maternal heart sound and fetal heart sound, respectively, obtained from the same mmWave non-contact radar-based maternal / fetal physiological activity monitoring system used to obtain the maternal breathing plot of FIG. 5. The results of FIGS. 5, 6A, and 6B were obtained simultaneously.

[0068] Heart spectrograms obtained by non-contact radar-based systems and methods described herein are comparable to those obtained by conventionalultrasound-based systems and methods, as shown by comparing FIG. 7A to FIG. 7B, and by comparing FIG. 8A to FIG. 8B. FIG. 7A is a frequency response diagram (in frequency [Hz] versus time [s]) for fetal heart sound obtained from a non-contact radarbased maternal / fetal physiological activity monitoring system as disclosed herein. FIG. 7B is a frequency response diagram (in frequency [Hz] versus time [s]) for fetal heart sound obtained from a conventional contact-based ultrasound device. A similar frequency response is obtained by both methods, with less amplitude variation exhibited using the radar-based method. FIG. 8A is a plot of spectrum power [dB] versus beats / m inute derived from a non-contact radar-based maternal / fetal physiological activity monitoring system as disclosed herein, while FIG. 8B is a plot of spectrum power [dB] versus beats / minute derived from a conventional contact-based ultrasound device, to provide a basis for comparison to FIG. 8A. Both the radar-based and ultrasound-based methods give an identical fetal heart rate of 135 beats per minute, as shown by the dominant peak locations (corresponding to peak spectral power values) marked by downwardly-pointing arrows in FIGS. 8A and 8B.

[0069] FIG. 9 is a block diagram including components of a radar-based maternal / fetal physiological activity monitoring system 10 according to embodiments disclosed herein. The maternal / fetal physiological activity monitoring system 10 includes, or is implemented with or as, a computer system 200, which comprises any computing or electronic device capable of including firmware, hardware, and / or executing software instructions that could be used to perform any of the methods or functions described above. In this regard, the computer system 200 may be a circuit or circuits included in an electronic board card, such as a printed circuit board (PCB), a server, a personal computer, a desktop computer, a laptop computer, an array of computers, a personal digital assistant (PDA), a computing pad, a mobile device, or any other device, and may represent, for example, a server or a user’s computer.

[0070] The exemplary computer system 200 in this embodiment includes a processing device 202 or processor, a system memory 204, and a system bus 206. The processing device 202 represents one or more commercially available or proprietary general-purpose processing devices, such as a microprocessor, central processing unit (CPU), or the like. More particularly, the processing device 202 may be a complexinstruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or other processors implementing a combination of instruction sets. The processing device 202 is configured to execute processing logic instructions for performing the operations and steps discussed herein.

[0071] In this regard, the various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with the processing device 202, which may be a microprocessor, field programmable gate array (FPGA), a digital signal processor (DSP), an applicationspecific integrated circuit (ASIC), or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. Furthermore, the processing device 202 may be a microprocessor, or may be any conventional processor, controller, microcontroller, or state machine. The processing device 202 may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0072] The system memory 204 may include non-volatile memory 208 and volatile memory 210. The non-volatile memory 208 may include read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and the like. The volatile memory 210 generally includes random-access memory (RAM) (e.g., dynamic random-access memory (DRAM), such as synchronous DRAM (SDRAM)). A basic input / output system (BIOS) 212 may be stored in the non-volatile memory 208 and can include the basic routines that help to transfer information between elements within the computer system 200.

[0073] The system bus 206 provides an interface for system components including, but not limited to, the system memory 204 and the processing device 202. The system bus 206 may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and / or a local bus using any of a variety of commercially available bus architectures.

[0074] The computer system 200 may further include or be coupled to a non- transitory computer-readable storage medium, such as a storage device 214, which may represent an internal or external hard disk drive (HDD), flash memory, or the like. The storage device 214 and other drives associated with computer-readable media and computer-usable media may provide non-volatile storage of data, data structures, computer-executable instructions, and the like. Although the description of computer- readable media above refers to an HDD, it should be appreciated that other types of media that are readable by a computer, such as optical disks, magnetic cassettes, flash memory cards, cartridges, and the like, may also be used in the operating environment, and, further, that any such media may contain computer-executable instructions for performing novel methods of the disclosed embodiments.

[0075] An operating system 216 and any number of program modules 218 or other applications can be stored in the volatile memory 210, wherein the program modules 218 represent a wide array of computer-executable instructions corresponding to programs, applications, functions, and the like that may implement the functionality described herein in whole or in part, such as through instructions 220 on the processing device 202. The program modules 218 may also reside on the storage mechanism provided by the storage device 214. As such, all or a portion of the functionality described herein may be implemented as a computer program product stored on a transitory or non-transitory computer-usable or computer-readable storage medium, such as the storage device 214, volatile memory 210, non-volatile memory 208, instructions 220, and the like. The computer program product includes complex programming instructions, such as complex computer-readable program code, to cause the processing device 202 to carry out the steps necessary to implement the functions described herein.

[0076] An operator, such as the user, may also be able to enter one or more configuration commands to the computer system 200 through a keyboard, a pointing device such as a mouse, or a touch-sensitive surface, such as the display device, via an input device interface 222 or remotely through a web interface, terminal program, or the like via a communication interface 224. The communication interface 224 may be wired or wireless and facilitate communications with any number of devices via acommunications network in a direct or indirect fashion. An output device, such as a display device, can be coupled to the system bus 206 and driven by a video port 226. Additional inputs and outputs to the computer system 200 may be provided through the system bus 206 as appropriate to implement embodiments described herein.

[0077] Systems and methods disclosed herein can extract the cardiac sound and measure the rate and rhythm of a fetal heartbeat, as well as measure rate and rhythm of maternal cardiac and respiratory functions, and provide audio information. Operation is provided through regular layers of clothing / blankets providing privacy and convenience. Maternal and fetal information can be separated through radar beam steering operation. Systems disclosed herein may be embodied in stand-alone (e.g., positionally fixed) devices or hand-held devices to enable more directed spot checks. Systems and methods disclosed herein can automatically locate a heartbeat source and can also extract multiple heartbeats in multiple pregnancy cases. Such systems can provide continuous, real-time measurements of vital information for both an expectant mother and fetus. Useful contexts include prenatal care and fetal health monitoring, pregnancy care (either point of care or in-hospital), and in-home screening.

[0078] The operational steps described in any of the exemplary embodiments herein are described to provide examples and discussion. The operations described may be performed in numerous different sequences other than the illustrated sequences. Furthermore, operations described in a single operational step may actually be performed in a number of different steps. Additionally, one or more operational steps discussed in the exemplary embodiments may be combined.

[0079] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the invention.

[0080] Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the description and claims are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It is intended that the embodiments cover the modifications and variations ofthe embodiments provided they come within the scope of the appended claims and their equivalents. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

CLAIMSWhat is claimed is:1 . A non-contact maternal I fetal physiological activity monitoring system, comprising: a radar sensor configured to be positioned in a signal-receiving range separated apart from a pregnant female subject; and a signal processor configured to: receive a radar signal from the radar sensor; select at least one pair of range and angle coordinates of the received radar signal and, for each selected pair of angle and range coordinates, generating a selected heart activity signal associated with the selected pair of range and angle coordinates; for each selected pair of range and angle coordinates, filter the selected heart activity signal utilizing a high-pass or bandpass filtering scheme to generate a filtered heart activity signal; and for each selected pair of range and angle coordinates, process the filtered heart activity signal to generate an estimated heart rate signal and an audio signal including a cardiac acoustic signal.

2. The system of claim 1 , wherein the at least one selected heart activity signal corresponds to a fetal heart activity signal, the estimated heart rate signal comprises a fetal heart rate signal, and the cardiac acoustic signal comprises a fetal cardiac acoustic signal.

3. The system of claim 1 , wherein the at least one selected heart activity signal corresponds to a maternal heart activity signal, the estimated heart rate signal comprises a maternal heart rate signal, and the cardiac acoustic signal comprises a maternal cardiac acoustic signal.

4. The system of claim 1 , wherein the at least one pair of angle and range coordinates selected by the signal processor comprises a first pair of angle and range coordinates corresponding to a fetal heart activity signal, and comprises a second pair of angle and range coordinates corresponding to a maternal heart activity signal.

5. The system of claim 1 , wherein the at least one pair of angle and range coordinates selected by the signal processor comprises a first pair of angle and range coordinates corresponding to a first fetal heart activity signal, and comprises a second pair of angle and range coordinates corresponding to a second fetal heart activity signal.

6. The system of claim 1 , wherein the signal processor is further configured to perform clutter mitigation on the received radar signal.

7. The system of claim 1 , wherein the radar signal comprises a millimeter- wave radar signal.

8. A non-contact method for maternal I fetal physiological activity monitoring, the method comprising: receiving, by a radar sensor, a radar signal comprising a reflection of an emitted radar signal impinged on a pregnant female subject; selecting, by a signal processor, at least one pair of range and angle coordinates of the received radar signal; for each selected pair of angle and range coordinates, generating, by the signal processor, a selected heart activity signal associated with each selected pair of range and angle coordinates; for each selected pair of range and angle coordinates, filtering, by the signal processor, the selected heart activity signal utilizing a high-pass or bandpass filtering scheme to generate a filtered heart activity signal; andfor each selected pair of range and angle coordinates, processing, by the signal processor, the filtered heart activity signal to generate an estimated heart rate signal and an audio signal including a cardiac acoustic signal.

9. The method of claim 8, wherein the at least one selected heart activity signal corresponds to a fetal heart activity signal, the estimated heart rate signal comprises a fetal heart rate signal, and the cardiac acoustic signal comprises a fetal cardiac acoustic signal.

10. The method of claim 8, wherein the at least one selected heart activity signal corresponds to a maternal heart activity signal, the estimated heart rate signal comprises a maternal heart rate signal, and the cardiac acoustic signal comprises a maternal cardiac acoustic signal.11 . The method of claim 8, wherein the at least one pair of angle and range coordinates selected by the signal processor comprises a first pair of angle and range coordinates corresponding to a fetal heart activity signal, and comprises a second pair of angle and range coordinates corresponding to a maternal heart activity signal.

12. The method of claim 8, wherein the at least one pair of angle and range coordinates selected by the signal processor comprises a first pair of angle and range coordinates corresponding to a first fetal heart activity signal, and comprises a second pair of angle and range coordinates corresponding to a second fetal heart activity signal.

13. The method of claim 8, further comprising performing, by the signal processor, clutter mitigation on the received radar signal.

14. The method of claim 8, wherein the received radar signal comprises a millimeterwave radar signal.

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