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2 pages, 160 KiB

Open AccessEditorial

Ultra-Wideband (UWB) Systems in Biomedical Sensing

by Gianluigi Tiberi and Mohammad Ghavami

Sensors 2022, 22(12), 4403; https://doi.org/10.3390/s22124403 - 10 Jun 2022

Cited by 5 | Viewed by 2071

Abstract

The extremely low power transmission levels of ultra-wideband (UWB) technology, alongside its advantageously large bandwidth, make it a prime candidate for being used in numerous healthcare scenarios, which require short-range high-data-rate communications and safe radar-based applications [...] Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

Research

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24 pages, 2441 KiB

Open AccessArticle

Respiration Based Non-Invasive Approach for Emotion Recognition Using Impulse Radio Ultra Wide Band Radar and Machine Learning

by Hafeez Ur Rehman Siddiqui, Hina Fatima Shahzad, Adil Ali Saleem, Abdul Baqi Khan Khakwani, Furqan Rustam, Ernesto Lee, Imran Ashraf and Sandra Dudley

Sensors 2021, 21(24), 8336; https://doi.org/10.3390/s21248336 - 13 Dec 2021

Cited by 21 | Viewed by 3767

Abstract

Emotion recognition gained increasingly prominent attraction from a multitude of fields recently due to their wide use in human-computer interaction interface, therapy, and advanced robotics, etc. Human speech, gestures, facial expressions, and physiological signals can be used to recognize different emotions. Despite the [...] Read more.

Emotion recognition gained increasingly prominent attraction from a multitude of fields recently due to their wide use in human-computer interaction interface, therapy, and advanced robotics, etc. Human speech, gestures, facial expressions, and physiological signals can be used to recognize different emotions. Despite the discriminating properties to recognize emotions, the first three methods have been regarded as ineffective as the probability of human’s voluntary and involuntary concealing the real emotions can not be ignored. Physiological signals, on the other hand, are capable of providing more objective, and reliable emotion recognition. Based on physiological signals, several methods have been introduced for emotion recognition, yet, predominantly such approaches are invasive involving the placement of on-body sensors. The efficacy and accuracy of these approaches are hindered by the sensor malfunctioning and erroneous data due to human limbs movement. This study presents a non-invasive approach where machine learning complements the impulse radio ultra-wideband (IR-UWB) signals for emotion recognition. First, the feasibility of using IR-UWB for emotion recognition is analyzed followed by determining the state of emotions into happiness, disgust, and fear. These emotions are triggered using carefully selected video clips to human subjects involving both males and females. The convincing evidence that different breathing patterns are linked with different emotions has been leveraged to discriminate between different emotions. Chest movement of thirty-five subjects is obtained using IR-UWB radar while watching the video clips in solitude. Extensive signal processing is applied to the obtained chest movement signals to estimate respiration rate per minute (RPM). The RPM estimated by the algorithm is validated by repeated measurements by a commercially available Pulse Oximeter. A dataset is maintained comprising gender, RPM, age, and associated emotions which are further used with several machine learning algorithms for automatic recognition of human emotions. Experiments reveal that IR-UWB possesses the potential to differentiate between different human emotions with a decent accuracy of 76% without placing any on-body sensors. Separate analysis for male and female participants reveals that males experience high arousal for happiness while females experience intense fear emotions. For disgust emotion, no large difference is found for male and female participants. To the best of the authors’ knowledge, this study presents the first non-invasive approach using the IR-UWB radar for emotion recognition. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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15 pages, 1868 KiB

Open AccessArticle

Validation of a New Contactless and Continuous Respiratory Rate Monitoring Device Based on Ultra-Wideband Radar Technology

by Timo Lauteslager, Michal Maslik, Fares Siddiqui, Saad Marfani, Guy D. Leschziner and Adrian J. Williams

Sensors 2021, 21(12), 4027; https://doi.org/10.3390/s21124027 - 11 Jun 2021

Cited by 15 | Viewed by 5514

Abstract

Respiratory rate (RR) is typically the first vital sign to change when a patient decompensates. Despite this, RR is often monitored infrequently and inaccurately. The Circadia Contactless Breathing Monitor™ (model C100) is a novel device that uses ultra-wideband radar to monitor RR continuously [...] Read more.

Respiratory rate (RR) is typically the first vital sign to change when a patient decompensates. Despite this, RR is often monitored infrequently and inaccurately. The Circadia Contactless Breathing Monitor™ (model C100) is a novel device that uses ultra-wideband radar to monitor RR continuously and un-obtrusively. Performance of the Circadia Monitor was assessed by direct comparison to manually scored reference data. Data were collected across a range of clinical and non-clinical settings, considering a broad range of user characteristics and use cases, in a total of 50 subjects. Bland–Altman analysis showed high agreement with the gold standard reference for all study data, and agreement fell within the predefined acceptance criteria of ±5 breaths per minute (BrPM). The 95% limits of agreement were −3.0 to 1.3 BrPM for a nonprobability sample of subjects while awake, −2.3 to 1.7 BrPM for a clinical sample of subjects while asleep, and −1.2 to 0.7 BrPM for a sample of healthy subjects while asleep. Accuracy rate, using an error margin of ±2 BrPM, was found to be 90% or higher. Results demonstrate that the Circadia Monitor can effectively and efficiently be used for accurate spot measurements and continuous bedside monitoring of RR in low acuity settings, such as the nursing home or hospital ward, or for remote patient monitoring. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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20 pages, 3773 KiB

Open AccessArticle

Ultra-Wideband Radar-Based Indoor Activity Monitoring for Elderly Care

by Matti Hämäläinen, Lorenzo Mucchi, Stefano Caputo, Lorenzo Biotti, Lorenzo Ciani, Dania Marabissi and Gabriele Patrizi

Sensors 2021, 21(9), 3158; https://doi.org/10.3390/s21093158 - 2 May 2021

Cited by 24 | Viewed by 7899

Abstract

In this paper, we propose an unobtrusive method and architecture for monitoring a person’s presence and collecting his/her health-related parameters simultaneously in a home environment. The system is based on using a single ultra-wideband (UWB) impulse-radar as a sensing device. Using UWB radars, [...] Read more.

In this paper, we propose an unobtrusive method and architecture for monitoring a person’s presence and collecting his/her health-related parameters simultaneously in a home environment. The system is based on using a single ultra-wideband (UWB) impulse-radar as a sensing device. Using UWB radars, we aim to recognize a person and some preselected movements without camera-type monitoring. Via the experimental work, we have also demonstrated that, by using a UWB signal, it is possible to detect small chest movements remotely to recognize coughing, for example. In addition, based on statistical data analysis, a person’s posture in a room can be recognized in a steady situation. In addition, we implemented a machine learning technique (k-nearest neighbour) to automatically classify a static posture using UWB radar data. Skewness, kurtosis and received power are used in posture classification during the postprocessing. The classification accuracy achieved is more than 99%. In this paper, we also present reliability and fault tolerance analyses for three kinds of UWB radar network architectures to point out the weakest item in the installation. This information is highly important in the system’s implementation. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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16 pages, 5350 KiB

Open AccessArticle

Brachialis Pulse Wave Measurements with Ultra-Wide Band and Continuous Wave Radar, Photoplethysmography and Ultrasonic Doppler Sensors

by Horst Hellbrück, Gunther Ardelt, Philipp Wegerich and Hartmut Gehring

Sensors 2021, 21(1), 165; https://doi.org/10.3390/s21010165 - 29 Dec 2020

Cited by 5 | Viewed by 2993

Abstract

The measurement and analysis of the arterial pulse wave provides information about the state of vascular health. When measuring blood pressure according to Riva-Rocci, the systolic and diastolic blood pressure is measured non-invasively with an inflatable pressure cuff on the upper arm. Today’s [...] Read more.

The measurement and analysis of the arterial pulse wave provides information about the state of vascular health. When measuring blood pressure according to Riva-Rocci, the systolic and diastolic blood pressure is measured non-invasively with an inflatable pressure cuff on the upper arm. Today’s blood pressure monitors analyze the pulse wave in reference to the rising or falling cuff pressure. With the help of additional pulse wave analysis, one can determine the pulse rate and the heart rate variability. In this paper, we investigated the concept, the construction, and the limitations of ultrawideband (UWB) radar and continuous wave (CW) radar, which provide continuous and non-invasive pulse wave measurements. We integrated the sensors into a complete measurement system. We measured the pulse wave of the cuff pressure, the radar sensor (both UWB and CW), the optical sensor, and ultrasonic Doppler as a reference. We discussed the results and the sensor characteristics. The main conclusion was that the resolution of the pulse radar was too low, even with a maximum bandwidth of 10 GHz, to measure pulse waves reliably. The continuous wave radar provides promising results for a phantom if adjusted properly with phase shifts and frequency. In the future, we intend to develop a CW radar solution with frequency adaption. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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15 pages, 2302 KiB

Open AccessArticle

Developing Artefact Removal Algorithms to Process Data from a Microwave Imaging Device for Haemorrhagic Stroke Detection

by Behnaz Sohani, James Puttock, Banafsheh Khalesi, Navid Ghavami, Mohammad Ghavami, Sandra Dudley and Gianluigi Tiberi

Sensors 2020, 20(19), 5545; https://doi.org/10.3390/s20195545 - 28 Sep 2020

Cited by 14 | Viewed by 4218

Abstract

In this paper, we present an investigation of different artefact removal methods for ultra-wideband Microwave Imaging (MWI) to evaluate and quantify current methods in a real environment through measurements using an MWI device. The MWI device measures the scattered signals in a multi-bistatic [...] Read more.

In this paper, we present an investigation of different artefact removal methods for ultra-wideband Microwave Imaging (MWI) to evaluate and quantify current methods in a real environment through measurements using an MWI device. The MWI device measures the scattered signals in a multi-bistatic fashion and employs an imaging procedure based on Huygens principle. A simple two-layered phantom mimicking human head tissue is realised, applying a cylindrically shaped inclusion to emulate brain haemorrhage. Detection has been successfully achieved using the superimposition of five transmitter triplet positions, after applying different artefact removal methods, with the inclusion positioned at 0

^{°}

, 90

^{°}

, 180

^{°}

, and 270

^{°}

. The different artifact removal methods have been proposed for comparison to improve the stroke detection process. To provide a valid comparison between these methods, image quantification metrics are presented. An “ideal/reference” image is used to compare the artefact removal methods. Moreover, the quantification of artefact removal procedures through measurements using MWI device is performed. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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15 pages, 1374 KiB

Open AccessArticle

Investigation of an Ultra Wideband Noise Sensor for Health Monitoring

by Xuezhi Zeng, Joakim Robakowski, Mikael Persson, Albert Monteith and Andreas Fhager

Sensors 2020, 20(4), 1034; https://doi.org/10.3390/s20041034 - 14 Feb 2020

Cited by 5 | Viewed by 3062

Abstract

Quick on-scene assessment and early intervention is the key to reduce the mortality of stroke and trauma patients, and it is highly desirable to develop ambulance-based diagnostic and monitoring devices in order to provide additional support to the medical personnel. We developed a [...] Read more.

Quick on-scene assessment and early intervention is the key to reduce the mortality of stroke and trauma patients, and it is highly desirable to develop ambulance-based diagnostic and monitoring devices in order to provide additional support to the medical personnel. We developed a compact and low cost ultra wideband noise sensor for medical diagnostics and vital sign monitoring in pre-hospital settings. In this work, we demonstrated the functionality of the sensor for respiration and heartbeat monitoring. In the test, metronome was used to manipulate the breathing pattern and the heartbeat rate reference was obtained with a commercial electrocardiogram (ECG) device. With seventeen tests performed for respiration rate detection, sixteen of them were successfully detected. The results also show that it is possible to detect the heartbeat rate accurately with the developed sensor. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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11 pages, 3285 KiB

Open AccessArticle

High Efficient and Ultra Wide Band Monopole Antenna for Microwave Imaging and Communication Applications

by Shahid Ullah, Cunjun Ruan, Muhammad Shahzad Sadiq, Tanveer Ul Haq and Wenlong He

Sensors 2020, 20(1), 115; https://doi.org/10.3390/s20010115 - 23 Dec 2019

Cited by 52 | Viewed by 7207

Abstract

The paper presents a highly efficient, low cost, ultra-wideband, microstrip monopole antenna for microwave imaging and wireless communications applications. A new structure (z-shape, ultra-wideband (UWB) monopole) is designed, which consists of stepped meander lines to achieve super-wide bandwidth and high efficiency. Three steps [...] Read more.

The paper presents a highly efficient, low cost, ultra-wideband, microstrip monopole antenna for microwave imaging and wireless communications applications. A new structure (z-shape, ultra-wideband (UWB) monopole) is designed, which consists of stepped meander lines to achieve super-wide bandwidth and high efficiency. Three steps are used to design the proposed structure for the purpose to achieve high efficiency and wide bandwidth. The antenna bandwidth is enhanced by varying the length of meander line slots, optimization of the feeding line and with the miniaturization of the ground width. The simulated and measured frequency bands are 2.7–22.5 GHz and 2.8–22.7 GHz (156% fractional bandwidth), respectively. The dimensions of the antenna are 38 mm × 35 mm × 1.57 mm, and its corresponding electrical size is 2.41 λg × 2.22 λg × 0.09 λg, where guided wavelength λg is at the center frequency (12.75 GHz). This antenna achieved a high bandwidth ratio (8.33:1). The realized gain is varying from 1.6–6.4 dBi, while that of efficiency is 70% to 93% for the whole band. Radiation patterns are measured at four operating frequencies. It has an acceptable group delay, fidelity factor, and phase variation results that satisfy the limit of ultra-wideband in the form of the time domain. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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Other

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10 pages, 1712 KiB

Open AccessLetter

Time-Domain Investigation of Switchable Filter Wide-Band Antenna for Microwave Breast Imaging

by Amir Haider, MuhibUr Rahman, Mahdi Naghshvarianjahromi and Hyung Seok Kim

Sensors 2020, 20(15), 4302; https://doi.org/10.3390/s20154302 - 1 Aug 2020

Cited by 10 | Viewed by 2663

Abstract

This paper investigates the time-domain performance of a switchable filter impulse radio ultra-wideband (IR-UWB) antenna for microwave breast imaging applications. A miniaturized CPW-fed integrated filter antenna with switchable performance in the range of the Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local [...] Read more.

This paper investigates the time-domain performance of a switchable filter impulse radio ultra-wideband (IR-UWB) antenna for microwave breast imaging applications. A miniaturized CPW-fed integrated filter antenna with switchable performance in the range of the Worldwide Interoperability for Microwave Access (WiMAX) and Wireless Local Area Network (WLAN) bands could operate well within a 3.0 to 11 GHz frequency range. The time-domain performance of the filter antenna was investigated in comparison to that of the designed reference wideband antenna. By comparing both antennas’ time-domain characteristics, it was seen that the switchable filter antenna had good time-domain resolution along with the frequency-domain operation. Additionally, the time-domain investigation revealed that the switchable filter wide-band antenna performed similarly to the reference wide band antenna. This antenna was also utilized for a tumor detection application, and it was seen that the switchable filter wide-band antenna could detect a miniaturized irregularly shaped tumor easily, which is quite promising. Such an antenna with a good time-domain resolution and tumor detection capability will be a good candidate and will find potential applications in microwave breast imaging. Full article

(This article belongs to the Special Issue Ultra Wideband (UWB) Systems in Biomedical Sensing)

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