Statistics for Spatial Data.

Advances in wireless technologies, low-power electronics, the internet of things, and in the domain of connected health are driving innovations in wearable medical devices at a tremendous pace. Wearable sensor systems composed of flexible and stretchable materials have the potential to better interface to the human skin, whereas silicon-based electronics are extremely efficient in sensor data processing and transmission. Therefore, flexible and stretchable sensors combined with low-power silicon-based electronics are a viable and efficient approach for medical monitoring. Flexible medical devices designed for monitoring human vital signs, such as body temperature, heart rate, respiration rate, blood pressure, pulse oxygenation, and blood glucose have applications in both fitness monitoring and medical diagnostics. As a review of the latest development in flexible and wearable human vitals sensors, the essential components required for vitals sensors are outlined and discussed here, including the reported sensor systems, sensing mechanisms, sensor fabrication, power, and data processing requirements.

Monitoring of Vital Signs with Flexible and Wearable Medical Devices

The introduction of intelligent textile systems to increase the wearer's level of protection has exposed the necessity of wearable communication tools and has led to research in textile antennas. However, most textile fabrics are quite thin (0.5 mm), making it challenging for antenna designers to provide an antenna which operates adequately and resiliently in the 2.4-2.4835-GHz industrial-scientific-medical bandwidth. Flexible pad foam is commonly available in protective clothing and overcomes these constraints by providing a uniform, stable, and sufficient thickness. Moreover, its cellular structure and properties, such as flame retardance and water repellence, make it an excellent substrate material for the integration of antennas into protective garments. In this paper, we describe the design, manufacture, and performance of the first textile planar antenna to be implemented on flexible protective foam, suitable for firefighter garments. We employed shock absorbing foam with a thickness of 3.94 mm and achieved a nearly circularly polarized antenna with a bandwidth of more than 180 MHz even when the antenna was compressed or bent. These outstanding substrate and antenna characteristics result in an antenna that is highly appropriate for garment integration.

A Textile Antenna for Off-Body Communication Integrated Into Protective Clothing for Firefighters

In the broad context of Wireless Body Sensor Networks for healthcare and pervasive applications, the design of wearable antennas offers the possibility of ubiquitous monitoring, communication and energy harvesting and storage. Specific requirements for wearable antennas are a planar structure and flexible construction materials. Several properties of the materials influence the behaviour of the antenna. For instance, the bandwidth and the efficiency of a planar microstrip antenna are mainly determined by the permittivity and the thickness of the substrate. The use of textiles in wearable antennas requires the characterization of their properties. Specific electrical conductive textiles are available on the market and have been successfully used. Ordinary textile fabrics have been used as substrates. However, little information can be found on the electromagnetic properties of regular textiles. Therefore this paper is mainly focused on the analysis of the dielectric properties of normal fabrics. In general, textiles present a very low dielectric constant that reduces the surface wave losses and increases the impedance bandwidth of the antenna. However, textile materials are constantly exchanging water molecules with the surroundings, which affects their electromagnetic properties. In addition, textile fabrics are porous, anisotropic and compressible materials whose thickness and density might change with low pressures. Therefore it is important to know how these characteristics influence the behaviour of the antenna in order to minimize unwanted effects. This paper presents a survey of the key points for the design and development of textile antennas, from the choice of the textile materials to the framing of the antenna. An analysis of the textile materials that have been used is also presented.

Textile materials for the design of wearable antennas: a survey.

Utilization of wearable textiles in the antenna segment has been seen on the rise due to the recent miniaturization of wireless devices. A wearable antenna is meant to be a part of the clothing used for communication purposes, which includes tracking and navigation, mobile computing and public safety. This literature review intend to disclose this unconventional antenna technology and provides readers with the background of the wearable antenna that would include about specification of the antenna, material for the antenna and analysis that must be done to design proper wearable antennas. All the designs presented are of the recent development in wearable technology.

A review of wearable antenna

Efficient textile antenna design is based on an accurate knowledge of the electromagnetic properties of textile materials. Therefore, we propose a characterization method that removes the perturbations in the calculated properties, due to imperfect deembedding and inhomogeneities of the textile microstrip line structure. Keywords— wearable antennas, permittivity, loss tangent, textile transmission lines

https://biblio.ugent.be/publication/677906/file/679440.pdf

Characterization of the electromagnetic properties of textile fabrics for the use in wearable antennas

The performance of wireless data communication links for fully equipped firemen walking indoor and communicating through textile patch antennas integrated into their clothing is investigated. Diversity techniques are evaluated for fourth order receiver diversity. This paper focuses on the dynamic channel estimation needed for communication between a fixed base station and a moving fireman over a time-variant channel subject to the multipath propagation in an indoor environment.

https://biblio.ugent.be/publication/797987/file/797998.pdf

Off-body communication in a multipath environment over time-variant channels using multiple textile antennas for the 2.45 GHz band

Active Wearable Antenna Modules

In wearable antenna design, the prevailing atmospheric conditions can have a significant effect on the electromagnetic properties of the fabric substrate and hence the resulting antenna performances. Therefore, an accurate characterization of this effect is an important issue in textile antenna design. This paper presents a dedicated constitutive parameter extraction method as a function of relative humidity of all materials used. The method relies on a comparison between measured and simulated antenna figure's of merit in order to extract complex permittivity of the substrate and effective bulk conductivity of the e-textile. A two-step approach is used for separating conductor losses from substrate losses. The problem of finding the best fit between simulated and measured data is solved by relying on a surrogate based optimization technique. Here, two fabric materials are characterized for relative humidity levels ranging from 10% to 90%.

/pdf/environmental-electromagnetic-characterization-framework-for-abzq2ei479.pdf

Environmental electromagnetic characterization framework for wearable antenna materials

In low-cost receiver applications, the preselect filter is often omitted in order to reduce the footprint of the total system. However, the immunity of the receiver can be severely compromised by this approach. This paper focuses on the effects of co-located sources on the local oscillator (LO), specifically injection locking and pulling. To this end, a low-cost radio receiver (RF) front-end is designed for operation in the 2:45 GHz industrial, scientific and medical (ISM) radio band. In addition to the effects on the oscillator, the consequences on the receiver's performance are evaluated as well. For the first time in literature, this work demonstrates the critical necessity to take the potentially detrimental effects caused by injection locking and pulling into account during Electromagnetic Compatibility (EMC)-aware design.

/pdf/emc-aware-analysis-and-design-of-a-low-cost-receiver-circuit-3aaacjlijv.pdf

Frederick Declercq

Papers

Characterization of the electromagnetic properties of textile fabrics for the use in wearable antennas

Off-body communication in a multipath environment over time-variant channels using multiple textile antennas for the 2.45 GHz band

Active Wearable Antenna Modules

Environmental electromagnetic characterization framework for wearable antenna materials

EMC-aware analysis and design of a low-cost receiver circuit under injection locking and pulling