The design and development of wearable biosensor systems for health monitoring has garnered lots of attention in the scientific community and the industry during the last years. Mainly motivated by increasing healthcare costs and propelled by recent technological advances in miniature biosensing devices, smart textiles, microelectronics, and wireless communications, the continuous advance of wearable sensor-based systems will potentially transform the future of healthcare by enabling proactive personal health management and ubiquitous monitoring of a patient's health condition. These systems can comprise various types of small physiological sensors, transmission modules and processing capabilities, and can thus facilitate low-cost wearable unobtrusive solutions for continuous all-day and any-place health, mental and activity status monitoring. This paper attempts to comprehensively review the current research and development on wearable biosensor systems for health monitoring. A variety of system implementations are compared in an approach to identify the technological shortcomings of the current state-of-the-art in wearable biosensor solutions. An emphasis is given to multiparameter physiological sensing system designs, providing reliable vital signs measurements and incorporating real-time decision support for early detection of symptoms or context awareness. In order to evaluate the maturity level of the top current achievements in wearable health-monitoring systems, a set of significant features, that best describe the functionality and the characteristics of the systems, has been selected to derive a thorough study. The aim of this survey is not to criticize, but to serve as a reference for researchers and developers in this scientific area and to provide direction for future research improvements.

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A Survey on Wearable Sensor-Based Systems for Health Monitoring and Prognosis

Recent developments and technological advancements in wireless communication, MicroElectroMechanical Systems (MEMS) technology and integrated circuits has enabled low-power, intelligent, miniaturized, invasive/non-invasive micro and nano-technology sensor nodes strategically placed in or around the human body to be used in various applications, such as personal health monitoring. This exciting new area of research is called Wireless Body Area Networks (WBANs) and leverages the emerging IEEE 802.15.6 and IEEE 802.15.4j standards, specifically standardized for medical WBANs. The aim of WBANs is to simplify and improve speed, accuracy, and reliability of communication of sensors/actuators within, on, and in the immediate proximity of a human body. The vast scope of challenges associated with WBANs has led to numerous publications. In this paper, we survey the current state-of-art of WBANs based on the latest standards and publications. Open issues and challenges within each area are also explored as a source of inspiration towards future developments in WBANs.

Wireless Body Area Networks: A Survey

Wireless sensor networks for healthcare: A survey

Power consumption is forecast by the International Technology Roadmap of Semiconductors (ITRS) to pose long-term technical challenges for the semiconductor industry. The purpose of this paper is threefold: (1) to provide an overview of strategies for powering MEMS via non-regenerative and regenerative power supplies; (2) to review the fundamentals of piezoelectric energy harvesting, along with recent advancements, and (3) to discuss future trends and applications for piezoelectric energy harvesting technology. The paper concludes with a discussion of research needs that are critical for the enhancement of piezoelectric energy harvesting devices.

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Powering MEMS portable devices—a review of non-regenerative and regenerative power supply systems with special emphasis on piezoelectric energy harvesting systems

Skin is the largest organ of the human body, and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles, and dermis/epidermis. Soft, flexible, and stretchable electronic devices provide a novel platform to interface with soft tissues for robotic feedback and control, regenerative medicine, and continuous health monitoring. Here, we introduce the term “lab-on-skin” to describe a set of electronic devices that have physical properties, such as thickness, thermal mass, elastic modulus, and water-vapor permeability, which resemble those of the skin. These devices can conformally laminate on the epidermis to mitigate motion artifacts and mismatches in mechanical properties created by conventional, rigid electronics while simultaneously providing accurate, non-invasive, long-term, and continuous health monitoring. Recent progress in the design and fabrication of soft sensors with more advanced capabilities and enhanced reliability suggest an impending t...

Lab-on-Skin: A Review of Flexible and Stretchable Electronics for Wearable Health Monitoring

A wearable, wireless 2-channel electro-encephalography (EEG) system has been realized which functions fully autonomously, without any batteries. It is fully powered by human body heat using a thermo-electric generator which can produce over 2 mW at 23degC. It uses two of IMECpsilas ultra-low power biopotential electronics chips to record high-quality EEG signals. The whole system consumes only 0.8 mW, while sampling and transmitting 2 channels of 12-bit EEG data continuously at 256 Hz. Previous work has shown body-heat powered sensors such as a wireless temperature sensor or pulse oximeter with a low transmission duty cycle, but never before a continuously acquiring and transmitting system with complete power autonomy has been demonstrated.

Wearable Autonomous Wireless Electro-encephalography System Fully Powered by Human Body Heat

A single-input and single-output (SISO) frequency-modulated continuous wave (FMCW) radar architecture is proposed and in vivo demonstrated for remote 2-D localization (range and angular information) and vital signs monitoring of multiple subjects. The radar sensor integrates two frequency scanning antennas which allow angular separation and enable determining a 2-D map (range versus angle) of a room environment from which people can be distinguished from objects and clutter. After technical tests to validate the functionality of the proposed architecture and data processing algorithm, a practical setup was successfully demonstrated to locate human volunteers, at different absolute distances and orientations, and to retrieve their respiratory and heart rate information. Experimental results show that this radar sensor can monitor accurately the vital signs of multiple subjects within typical room settings, reporting maximum mean absolute errors of 0.747 breaths-per-minute and 2.645 beats-per-minute, respectively, for respiration rate and heartbeat. Practical applications arise for Internet of Things (IoT), ambient-assisted living, healthcare, geriatric and quarantine medicine, automotive, rescue and security purposes.

2-D Localization, Angular Separation and Vital Signs Monitoring Using a SISO FMCW Radar for Smart Long-Term Health Monitoring Environments

Smart Wireless Sensors Integrated in Clothing: an Electrocardiography System in a Shirt Powered Using Human Body Heat

A Doppler radar operating as a Phase-Locked-Loop (PLL) in frequency demodulator configuration is presented and discussed. The proposed radar presents a unique architecture, using a single channel mixer, and allows to detect contactless vital signs parameters while solving the null point issue and without requiring the small angle approximation condition. Spectral analysis, simulations, and experimental results are presented and detailed to demonstrate the feasibility and the operational principle of the proposed radar architecture.

Frequency-Tracking CW Doppler Radar Solving Small-Angle Approximation and Null Point Issues in Non-Contact Vital Signs Monitoring

A wireless network based on macro-scale sensor modules (originally 45/spl times/35/spl times/30 mm/sup 3/, currently 14/spl times/14/spl times/18 mm/sup 3/ with integrated coplanar antenna) has been demonstrated. The modules can extract their energy from the environment (e.g., by solar cells), and detect various environmental parameters. The network can be configured as a multi-hop "web" of sensors which builds itself automatically according to configurable optimization parameters, or as a "star" topology, where each sensor module transmits information directly to the base station. Average power consumption for each complete module is approximately 100 /spl mu/W. This ability for drastic miniaturization and the simultaneous addition of power autonomy while maintaining modularity and reusability contrast to existing work where wireless environmental sensor systems are at least one order of magnitude larger in volume or consisted of application-specific systems-on-a-chip.

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Tom Torfs

Papers

Wearable Autonomous Wireless Electro-encephalography System Fully Powered by Human Body Heat

2-D Localization, Angular Separation and Vital Signs Monitoring Using a SISO FMCW Radar for Smart Long-Term Health Monitoring Environments

Smart Wireless Sensors Integrated in Clothing: an Electrocardiography System in a Shirt Powered Using Human Body Heat

Frequency-Tracking CW Doppler Radar Solving Small-Angle Approximation and Null Point Issues in Non-Contact Vital Signs Monitoring

Wireless network of autonomous environmental sensors