No-touch measurements of vital signs in small conscious animals

Hui, Xiaonan; Kan, Edwin C.

doi:10.1126/sciadv.aau0169

Cited by 54 publications

(30 citation statements)

References 35 publications

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“…On the other hand, NCS can work over clothing and take advantage of the low cost and compact size in modern RF devices such as the smart phone. For various application scenarios, the NCS system can be adapted to the RFID system [4], wearable devices [4], [43], and dedicated in-clinic wired setup [17], [22], [44]. The standard digital filters in the above analyses can be easily realized on various platforms without heavy computational loads.…”

Section: Discussionmentioning

confidence: 99%

“…The NCS principle states that when a dielectric boundary moves in the near-field region of a transmitting or backscattering antenna, its motion becomes part of the antenna characteristics that can be evaluated after carrier demodulation and baseband filtering [4], [17]. Both carrier and baseband injection in NCS contributes to channel isolation and eventual multiplexing, and the near-field coupling provides the sensing locality.…”

Section: The Multi-point Ncs System Setupmentioning

confidence: 99%

“…The other three ports (Po2 to Po4) are similarly configured with Tx2 and Rx2 to Po2 in SDR1, Tx3 and Rx3 to Po3 in SDR2, and Tx4 and Rx4 to Po4 in SDR2. The RF signal at each Tx can be multiplexed with time-division multiple access (TDMA) [19], code division multiple access (CDMA) [20], [21] or, in the case of this work, frequency division multiple access (FDMA) [17], [22]. The carrier frequency is 1.82 GHz with 0.71 MHz, 1.22 MHz, 1.71 MHz and 2.33 MHz baseband offsets for Tx1 -Tx4, respectively.…”

Section: The Multi-point Ncs System Setupmentioning

confidence: 99%

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Multi-Point Near-Field RF Sensing of Blood Pressures and Heartbeat Dynamics

2020

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Systolic and diastolic blood pressure estimation using arm-cuff monitors is one of the most common cardiovascular evaluation criteria in healthcare today, however these measures lack critical heartbeat and pressure dynamics. Pulse-transit time can be used as an alternative for arm-cuff monitors, but gives only one parameter for two pressure quantities. Ultrasound, computed tomography scan, and magnetic resonance imaging can retrieve geometrical features of the heart, but cannot directly estimate vascular pressures. Here we show a novel radio-frequency heartbeat sensor based on multi-point near-field observation. By comparing to synchronized electrocardiogram and auscultation, the multi-point sensor can assess motion and pressure in different parts of the heart following the Wiggers diagram. By applying the Hilbert-Huang frequencytime transform, the central blood pressure can be derived from the vascular vibration characteristics as continuous transients, including during the pulmonary cycle which is previously inaccessible from branchial measurements. Our scheme can be further extended to a full multiple-input-multiple-output (MIMO) channel arrangement, producing rich content for diagnostic and biometric applications. We employ dynamic time warping analyses to illustrate the sensor's wealth of diversified information across different channels and persons. This new multi-point sensor, which can be worn conveniently over clothing, enables unprecedented monitoring capabilities of detailed central blood pressure transients and heartbeat dynamics under the given measurement instructions for at-home and clinical cardiovascular diagnostics.

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Section: Discussionmentioning

confidence: 99%

Section: The Multi-point Ncs System Setupmentioning

confidence: 99%

Section: The Multi-point Ncs System Setupmentioning

confidence: 99%

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Multi-Point Near-Field RF Sensing of Blood Pressures and Heartbeat Dynamics

2020

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“…The radar measured the antenna characteristics modulated by the dielectric boundary movement changes, while the ECG measured the body potential differences induced by the minute skin current further induced by the electrical heart stimulation and blood flow. In this perspective, the radar had a waveform transducing the internal and external mechanical motion of the heart, which is related to the mechanical information in ballistocardiogram and seismic cardiography [34,42,43]. Besides, we also used this radar to measure the physiological parameters (respiratory rate and heart rate) of cats and dogs when they were at rest.…”

Section: Data Acquisitionmentioning

confidence: 99%

“…To be sufficiently sensitive to the vital signs of small animals, they raised the carrier frequency to the millimeter-wave level, which not only increased the system cost but also reduced the operational distance. In addition, in [34], a radio frequency near-field coherent sensing (NCS) scheme was proposed to monitor small animals in the laboratory. However, the short detection range limits its applicability in monitoring vital signs of pets at home.…”

Section: Introductionmentioning

confidence: 99%

Non-Contact Vital Signs Monitoring of Dog and Cat Using a UWB Radar

Wang

Liang

et al. 2020

Animals

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Simple Summary: In this paper, we presented a new non-contact method to measure the vital signs of at-rest pets, where the ultra-wideband radar was applied for previously unachievable sensing ability and testing convenience. The proposed scheme did not interfere with the daily rhythm of the pet being tested; most subjects would not even notice the ongoing real-time monitoring due to the larger measurement coverage of the radar sensor. Through this work, we provided an innovative tool to promote not only the measurement of pet vital signs but also the improvement of animal welfare to prevent invasive, dangerous, and unacceptable contact measurement techniques, such as anesthesia, hair removal, and surgical implants. In addition, the proposed method could realize the daily vital signs measurement and sleep monitoring of dogs and cats, which is important for the diagnosis and timely treatment of pet diseases.Abstract: As pets are considered members of the family, their health has received widespread attention. Since pets cannot talk and complain when they feel uncomfortable, monitoring vital signs becomes very helpful in disease detection, as well as observing their progression and response to treatment. In this study, we proposed an ultra-wideband radar-based, non-contact animal vital sign monitoring scheme that could monitor the breathing and heart rate of a pet in real-time. The primary advantage of the ultra-wideband radar was its ability to operate remotely without electrodes or wires and through any clothing or fur. Because of the existing noise and clutter in non-contact detection, background noise removal was applied. Furthermore, the respiration rate was directly obtained through spectrum analysis, while the heartbeat signal was extracted by the variational mode decomposition algorithm. By using electrocardiogram measurements, we verified the accuracy of the radar technology in detecting the anesthetized animals' respiratory rate and heart rate. Besides, three beagles and five cats in a non-sedated state were measured by radar and contact pressure sensors simultaneously; the experimental results showed that radar could effectively measure the respiration of cats and dogs, and the accuracy rate was over 95%. Due to its excellent performance, the proposed method has the potential to become a new choice in application scenarios, such as pet sleep monitoring and health assessment.

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High‐Efficiency Spatial‐Wave Frequency Multiplication Using Strongly Nonlinear Metasurface

Wang

et al. 2021

Advanced Science

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In the past decades, metasurfaces have opened up a promising venue for manipulating lights and electromagnetic (EM) waves. In the field of nonlinearity, second-harmonic generation (SHG) is a research focus due to its diverse applications. There have been many researches for realizing SHG in optical regime using nonlinear characteristics of optical materials, but its efficiency is low. In microwave frequencies, SHGs are basically studied in the guided-wave systems. Here, high-efficiency SHGs of spatial waves are presented in the microwave frequency using nonlinear metasurface loaded with active chips at the subwavelength scale. The nonlinear meta-atom is composed of receiving antenna, transmitting antenna, and active circuit of frequency multiplier, which can realize strongly nonlinear response and link the EM signals from the receiving to transmitting antennas. Correspondingly, to achieve the function of spatial-wave frequency multiplication, the working frequency of the transmitting antenna in the meta-atom should be twice as that of the receiving antenna, and hence the active chip is well matched to obtain the signal transforming with high efficiency. Good performance of the spatial-wave frequency multiplication is demonstrated in the proof-of-concept experiments with the best transform efficiency of 85.11% under normal incidence, validating the proposed method.

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No-touch measurements of vital signs in small conscious animals

Abstract: Vital signs of small conscious animals are acquired in a civilized way without touching or interfering.

Cited by 54 publications

References 35 publications

Multi-Point Near-Field RF Sensing of Blood Pressures and Heartbeat Dynamics

Multi-Point Near-Field RF Sensing of Blood Pressures and Heartbeat Dynamics

Non-Contact Vital Signs Monitoring of Dog and Cat Using a UWB Radar

High‐Efficiency Spatial‐Wave Frequency Multiplication Using Strongly Nonlinear Metasurface

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