Zheyu Wang

Bio: Zheyu Wang is an academic researcher from Ohio State University. The author has contributed to research in topics: Antenna (radio) & Conformal antenna. The author has an hindex of 12, co-authored 29 publications receiving 704 citations. Previous affiliations of Zheyu Wang include John L. Scott & Samsung.

Embroidered Conductive Fibers on Polymer Composite for Conformal Antennas

Abstract: We provide a novel class of conformal antennas based on embroidered conductive metal-polymer fibers (E-fiber) on polymer-ceramic composites. This new technology offers attractive mechanical and RF performance when compared to traditional flat and rigid circuits and antennas. The proposed E-fiber components are consisted of high strength and flexible polymer fiber cores and conductive metallic coatings. They were fabricated using automatic embroidery process, followed by assembly with polydimethylsiloxane and rare-earth titanate ceramic composites. Such composite substrates were tape-casted, and capable of providing tunable dielectric constant from 3 to 12 with a low tanδ <; 10-2 up to GHz frequencies. Basic RF prototypes, such as transmission lines (TL), patch antennas, and antenna arrays were fabricated for experimental evaluation. Measurement of the prototypes were conducted and compared to their copper counterparts. The RF characteristics of the E-fiber TLs exhibited an insertion loss of only 0.03 dB/cm higher than copper TLs up to 4 GHz . Also, the E-fiber patch antenna and antenna array exhibited 0.3 dB and 0.6 dB lower gains, respectively, than their copper counterparts. When applied onto a cylindrical surface, both the E-fiber patch antenna and antenna array only suffered 1 dB loss in realized gain, which is quite remarkable when compared with traditional antennas.

Textile Antennas and Sensors for Body-Worn Applications

Abstract: This letter presents novel body-worn antennas and medical sensors based on embroidered conductive polymer fibers (e-fibers) on textiles. This technology offers attractive mechanical and RF performance when compared to traditionally flat and rigid antennas and circuits. The e-fibers are composed of high-strength and flexible polymer cores that incorporate conductive metallic coatings. They are readily embroidered onto regular textiles and can also be laminated on to polymer dielectric substrates. The RF characteristics of the e-fiber textiles were evaluated using microstrip transmission line (TL) structures. They exhibited an insertion loss of only 0.07 dB/cm at 1 GHz and 0.15 dB/cm at 2 GHz. Prototype body-worn multiband/wideband antennas and medical sensor were constructed to demonstrate their efficiency and comparable performance to that of copper. All designs were fabricated with high precision and resolution down to 0.5 mm.

Embroidered Multiband Body-Worn Antenna for GSM/PCS/WLAN Communications

Abstract: A novel textile-based body-worn antenna covering the Global System for Mobile Communications/personal communications services/wireless local-area network frequency bands is presented. This antenna was made of densely embroidered metal-coated polymer fibers (e-fibers). These e-fibers are 15 $\mu$ m thick and consist of high strength, flexible polymer cores with conductive silver coatings, providing mechanical flexibility and low loss at radio frequencies. When measured in free space, the textile antenna showed comparable performance to its copper counterpart, having ${\sim}2$ dBi realized gain at all three bands. This textile antenna was simulated and measured on a full body phantom to determine the body's influence on antenna performance, including frequency detuning and pattern shadowing. The measured radiation pattern of the body-worn antenna matched well with simulation at various on-body locations for the three bands. Field measurements were also carried out by mounting the antenna onto the shoulder of a jacket, and using it to replace the one of a cell phone. We found that the communication quality using the body-worn textile antenna was equivalent to the best location of the original cell-phone antenna. Therefore, this textile-based antenna provided for a more reliable body-worn communication when mounted on the body's shoulder.

Pulmonary Edema Monitoring Sensor With Integrated Body-Area Network for Remote Medical Sensing

Abstract: A wearable health monitoring sensor integrated with a body-area network is presented for the diagnosis of pulmonary edema. This sensor is composed of 17 electrodes with 16 ports in-between and is intended to be placed on the human chest to detect lung irregularities by measuring the lung's average dielectric permittivity in a non-invasive way. Specifically, the sensor's active port is fed by a 40 MHz RF signal and its passive ports measure the corresponding amplitudes of the scattering parameters (S-parameters). The dielectric constant of the lung is then post-processed and expressed as a weighted sum of the S-parameters measured from each port. An important aspect of the sensor is the use of multiple electrodes which mitigates the effect of the outer layers (skin, fat and muscle) on the lung's permittivity. This allows for the characterization of deeper tissue layers. To validate the sensor, tissue-emulating gels were employed to mimic in-vivo tissues. Measurements of the lung's permittivity in both healthy and pulmonary edema states are carried out to validate the sensor's efficacy. Using the proposed post processing technique, the calculated permittivity of the lung from the measured S-parameters demonstrated error less than 11% compared to the direct measured value. Concurrently, a medical sensing body-area network (MS-BAN) is also employed to provide for remote data transfer. Measured results via the MS-BAN are well matched to those obtained by direct measurement. Thus, the MS-BAN enables the proposed sensor with continuous and robust remote sensing capability.

Flexible textile antennas for body-worn communication

Abstract: This paper presents an embroidered body-worn antenna using conductive fibers (E-fibers). The antenna's conductive surfaces were fabricated using precise and automated embroidering techniques to produce fully flexible and conformal antenna elements attached to regular fabrics and clothing. These E-fiber antennas offer desirable mechanical properties without undermining electrical performance for body-worn, on-clothing applications at radio frequencies (RF). In this study, we used an embroidered asymmetric meandered flare (AMF) dipole antenna to validate the textile antenna's performance. Its excellent RF performance was found comparable to conventional printed antennas. Therefore, these new E-fiber antennas may be integrated into scarves, handbags, shirts, coats or hand bands for convenient carefree health monitoring and wideband communications.

Fiber‐Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications

Abstract: Fiber-based structures are highly desirable for wearable electronics that are expected to be light-weight, long-lasting, flexible, and conformable Many fibrous structures have been manufactured by well-established lost-effective textile processing technologies, normally at ambient conditions The advancement of nanotechnology has made it feasible to build electronic devices directly on the surface or inside of single fibers, which have typical thickness of several to tens microns However, imparting electronic functions to porous, highly deformable and three-dimensional fiber assemblies and maintaining them during wear represent great challenges from both views of fundamental understanding and practical implementation This article attempts to critically review the current state-of-arts with respect to materials, fabrication techniques, and structural design of devices as well as applications of the fiber-based wearable electronic products In addition, this review elaborates the performance requirements of the fiber-based wearable electronic products, especially regarding the correlation among materials, fiber/textile structures and electronic as well as mechanical functionalities of fiber-based electronic devices Finally, discussions will be presented regarding to limitations of current materials, fabrication techniques, devices concerning manufacturability and performance as well as scientific understanding that must be improved prior to their wide adoption

Wearable Electronics and Smart Textiles: A Critical Review

Abstract: Electronic Textiles (e-textiles) are fabrics that feature electronics and interconnections woven into them, presenting physical flexibility and typical size that cannot be achieved with other existing electronic manufacturing techniques. Components and interconnections are intrinsic to the fabric and thus are less visible and not susceptible of becoming tangled or snagged by surrounding objects. E-textiles can also more easily adapt to fast changes in the computational and sensing requirements of any specific application, this one representing a useful feature for power management and context awareness. The vision behind wearable computing foresees future electronic systems to be an integral part of our everyday outfits. Such electronic devices have to meet special requirements concerning wearability. Wearable systems will be characterized by their ability to automatically recognize the activity and the behavioral status of their own user as well as of the situation around her/him, and to use this information to adjust the systems' configuration and functionality. This review focuses on recent advances in the field of Smart Textiles and pays particular attention to the materials and their manufacturing process. Each technique shows advantages and disadvantages and our aim is to highlight a possible trade-off between flexibility, ergonomics, low power consumption, integration and eventually autonomy.

Ag Nanowire Reinforced Highly Stretchable Conductive Fibers for Wearable Electronics

Abstract: Stretchable conductive fi bers have received signifi cant attention due to their possibility of being utilized in wearable and foldable electronics. Here, highly stretchable conductive fi ber composed of silver nanowires (AgNWs) and silver nanoparticles (AgNPs) embedded in a styrene‐butadiene‐styrene (SBS) elastomeric matrix is fabricated. An AgNW-embedded SBS fi ber is fabricated by a simple wet spinning method. Then, the AgNPs are formed on both the surface and inner region of the AgNW-embedded fi ber via repeated cycles of silver precursor absorption and reduction processes. The AgNW-embedded conductive fi ber exhibits superior initial electrical conductivity ( σ 0 = 2450 S cm −1 ) and elongation at break (900% strain) due to the high weight percentage of the conductive fi llers and the use of a highly stretchable SBS elastomer matrix. During the stretching, the embedded AgNWs act as conducting bridges between AgNPs, resulting in the preservation of electrical conductivity under high strain (the rate of conductivity degradation, σ / σ 0 = 4.4% at 100% strain). The AgNW-embedded conductive fi bers show the strain-sensing behavior with a broad range of applied tensile strain. The AgNW reinforced highly stretchable conductive fi bers can be embedded into a smart glove for detecting sign language by integrating fi ve composite fi bers in the glove, which can successfully perceive human motions.

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

Abstract: 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.

A Switchable 3-D-Coverage-Phased Array Antenna Package for 5G Mobile Terminals

Abstract: This letter proposes a new design of millimeter-wave (mm-Wave) array antenna package with beam steering characteristic for the fifth-generation (5G) mobile applications. In order to achieve a broad three-dimensional scanning coverage of the space with high-gain beams, three identical subarrays of patch antennas have been compactly arranged along the edge region of the mobile phone printed circuit board (PCB) to form the antenna package. By switching the feeding to one of the subarrays, the desired direction of coverage can be achieved. The proposed design has >10-dB gain in the upper spherical space, good directivity, and efficiency, which is suitable for 5G mobile communications. In addition, the impact of the user's hand on the antenna performance has been investigated.