Wearable devices provide an alternative pathway to clinical diagnostics by exploiting various physical, chemical and biological sensors to mine physiological (biophysical and/or biochemical) information in real time (preferably, continuously) and in a non-invasive or minimally invasive manner. These sensors can be worn in the form of glasses, jewellery, face masks, wristwatches, fitness bands, tattoo-like devices, bandages or other patches, and textiles. Wearables such as smartwatches have already proved their capability for the early detection and monitoring of the progression and treatment of various diseases, such as COVID-19 and Parkinson disease, through biophysical signals. Next-generation wearable sensors that enable the multimodal and/or multiplexed measurement of physical parameters and biochemical markers in real time and continuously could be a transformative technology for diagnostics, allowing for high-resolution and time-resolved historical recording of the health status of an individual. In this Review, we examine the building blocks of such wearable sensors, including the substrate materials, sensing mechanisms, power modules and decision-making units, by reflecting on the recent developments in the materials, engineering and data science of these components. Finally, we synthesize current trends in the field to provide predictions for the future trajectory of wearable sensors. 

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End-to-end design of wearable sensors

This review paper summarizes various approaches developed in the literature for antenna sensors with an emphasis on flexible solutions. The survey helps to recognize the limitations and advantages of this technology. Furthermore, it offers an overview of the main points for the development and design of flexible antenna sensors from the selection of the materials to the framing of the antenna including the different scenario applications. With regard to wearable antenna sensors deployment, a review of the textile materials that have been employed is also presented. Several examples related to human body applications of flexible antenna sensors such as the detection of NaCl and sugar solutions, blood and bodily variables such as temperature, strain, and finger postures are also presented. Future investigation directions and research challenges are proposed.

https://www.mdpi.com/1996-1944/13/17/3781/pdf

A Review of Flexible Wearable Antenna Sensors: Design, Fabrication Methods, and Applications

Soft wearable devices for deep-tissue sensing

Wearable antennas have received a great deal of popularity in recent years owing to their enticing characteristics and opportunities to realize lightweight, compact, low-cost, and versatile wireless communications and environments. These antennas must be conformal, and they must be built using lightweight materials and constructed in a low-profile configuration when mounted on various areas of the human body. These antennas ought to be able to function close to the human body with limited deterioration. These criteria render the layout of wearable antennas demanding, particularly when considering factors such as investigating the usability of textile substrates, high conductive materials during fabrication processes, and the effect of body binding scenarios on the performance of the design. Although there are minor differences in magnitude based on the implementations, several of these problems occur in the body-worn deployment sense. This study addresses the numerous problems and obstacles in the production of wearable antennas, their variety of materials, and the techniques of manufacturing alongside with bending scheme. This is accompanied by a summary of creative features and their respective approaches to address these problems recently raised by work in this area by the science community. Â© 2020. All Rights Reserved.

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Recent Advances in Wearable Antenna Technologies: A Review

Ultra-wideband (UWB) technology can offer broad capacity, short-range communications at a relatively low level of energy usage, which is very desirable for wireless body area networks (WBANs). The involvement of the human body in such a device poses immense difficulties for both the architecture of the wearable antenna and the broadcast model. Initially, the bonding between the wearable antenna and the human body should also be acknowledged in the early stages of the design, so that both the potentially degrading output of the antenna as a consequence of the body and the possibility of exposure for the body may be handled. Next, the transmission path in WBAN is affected by the constant activity of the human body, leading to the time-varying dispersion of electromagnetic waves. Few researchers were interested in this field, and some substantial progress has recently been considered. On the other hand, this paper covered both wearable and Non-wearable UWB antenna designs and applications with respect to their substrate characteristics. Finally, this review prospectively exposes the upgraded developments of (ON-OFF) body antennas in the area of wearable and Non-wearable UWB and their implementations in the WBAN device and aims to evaluate the latest design features that inspire the performance of the antennas.

/pdf/on-off-body-ultra-wideband-uwb-antenna-for-wireless-body-pw985s2rr5.pdf

ON-OFF Body Ultra-Wideband (UWB) Antenna for Wireless Body Area Networks (WBAN): A Review

This paper is devoted to a novel textile ultra-wideband (UWB) antenna for wearable applications. The antenna is designed and implemented on a felt textile substrate with attractive features such as...

A novel ultra-wide band wearable antenna under different bending conditions for electronic-textile applications

Textile radio-frequency identification operating in ultra-high frequency (UHF-RFID) sensors based on different scenarios are becoming attractive with the forthcoming internet of things (IoT) era and aging society. Compared with conventional UHF-RFID sensors, textile UHF-RFID sensors offer the common textile features, light weight, washability and comfort. Due to the short time and low level of development, researches on the integration of textile UHF-RFID techniques and textile sensing techniques are not flourishing. This paper is motivated by this situation to identify the current research status. In this paper, we provide a systematic review of the fundamentals of textile UHF-RFID sensors techniques, materials, the brief history and the state-of-the-art of the scenario-based development through detailed summary and analysis on the achievements from the starting year of 2004 to the present time. Moreover, according to the analysis, we give a proposal of the future prospects in several aspects, including the new materials and manufacturing processes, machine learning technology, scenario-based applications and unavoidable reliability.

/pdf/wearable-textile-uhf-rfid-sensors-a-systematic-review-2t2t45gmp5.pdf

Wearable Textile UHF-RFID Sensors: A Systematic Review.

In this work, an embroidered textile moisture sensor is proposed and characterized with three different fabric substrates The sensors are based on a capacitive interdigitated structure embroidered

/pdf/experimental-analysis-of-fabric-substrate-on-a-moisture-2n2856aabg.pdf

Experimental analysis of fabric substrate on a moisture sensor

In this work, a wearable system to detect urine leakage based on a textile sensor is proposed. The system consists of a capacitive sensor embroidered with a conductive yarn in a cotton/polyester substrate. A microcontroller (MCU) with a wireless module for signal acquisition and a smartphone for monitoring complete the overall system. The capacitive sensor behaviour was tested in a climatic chamber between 30 % and 80% of relative humidity (RH) with a LCR meter and charge/discharge method directly connected to the MCU. The results show that the proposed system is able to detect urine leakage even though when the patient wears a diaper. The functionally allows to develop a real time monitoring system which can help nursing and medical assistants to take care of elderly and disabled people and improve the quality of life of these patients.

/pdf/a-wearable-system-to-detect-urine-leakage-based-on-a-textile-1nnay9vprr.pdf

Raúl Fernández-García

Papers

A Review of Flexible Wearable Antenna Sensors: Design, Fabrication Methods, and Applications

A novel ultra-wide band wearable antenna under different bending conditions for electronic-textile applications

Wearable Textile UHF-RFID Sensors: A Systematic Review.

Experimental analysis of fabric substrate on a moisture sensor

A wearable system to detect urine leakage based on a textile sensor.