Wearable Metamaterial Dual-Polarized High Isolation UWB MIMO Vivaldi Antenna for 5G and Satellite Communications

A low-profile Multiple Input Multiple Output (MIMO) antenna showing dual polarization, low mutual coupling, and acceptable diversity gain is presented by this paper. The antenna introduces the requirements of fifth generation (5G) and the satellite communications. A horizontally (4.8–31 GHz) and vertically polarized (7.6–37 GHz) modified antipodal Vivaldi antennas are simulated, fabricated, and integrated, and then their characteristics are examined. An ultra-wideband (UWB) at working bandwidths of 3.7–3.85 GHz and 5–40 GHz are achieved. Low mutual coupling of less than −22 dB is achieved after loading the antenna with cross-curves, staircase meander line, and integration of the metamaterial elements. The antennas are designed on a denim textile substrate with = 1.4 and h= 0.5 mm. A conductive textile called ShieldIt is utilized as conductor with conductivity of 1.8 × 104. After optimizing the proposed UWB-MIMO antenna’s characteristics, it is increased to four elements positioned at the four corners of a denim textile substrate to be employed as a UWB-MIMO antenna for handset communications, 5G, Ka and Ku band, and satellite communications (X-band). The proposed eight port UWB-MIMO antenna has a maximum gain of 10.7 dBi, 98% radiation efficiency, less than 0.01 ECC, and acceptable diversity gain. Afterwards, the eight-ports antenna performance is examined on a simulated real voxel hand and chest. Then, it is evaluated and compared on physical hand and chest of body. Evidently, the simulated and measured results show good agreement between them. The proposed UWB-MIMO antenna offers a compact and flexible design, which is suitably wearable for 5G and satellite communications applications.

An All-Textile Dual-Band Antenna for BLE and LoRa Wireless Communications

In this paper, a dual-band conductive textile-based wearable antenna operating at LoRa-868 MHz and BLE-2.4 GHz is presented. The proposed antenna is intended for accurate geolocation, tracking and communication applications in the military, industrial and telemedicine industries. The low-profile patch antenna is suitable for integrating into clothing. It is composed of three textile layers: top and bottom silver-ink-printed polystyrene fabrics, and a neoprene substrate. To utilize the flexible and restorable properties of these textile materials, the proposed antenna is directly fed by a flexible cable using an aperture-coupled feeding technique. This method not only eliminates the use of the conventional, bulky, and metallic SMA connector but also introduces a secondary resonance at 2.4 GHz, enabling the dual-band property. Using a thin coaxial cable fixed on the aperture slot for proximity coupling, a compact antenna size of 150 mm2 is obtained that can easily be attached and detached on existing cloths. The proposed structure has been fabricated and measured in an anechoic chamber to verify the performance. Measured gain of 3.28 dBi and 3.25 dBi was realized for LoRa and BLE at an antenna size of 0.61 λg × 0.61 λg × 0.012 λg (where λg is guided wavelength at 868 MHz) with a front-to-back ratio (FBR) of greater than 10 dBi.

Evaluation of a Textile PIFA for Wearable IoT Application and its Challenges

The ever increasing use of body-worn systems in the Internet of Things application such as needs better antenna subsystem designs compatible with its requirements. Several challenges limiting the performance of a body-worn system, from materials, and environmental conditions to the effects of on body application and its hazards are discussed. As a test case, a flexible textile planar inverted-F antenna is presented and discussed. The choice of this topology is due to its simplicity in design and fabrication, relatively broad bandwidth and the presence of a rear ground plane, which minimizes the impacts of the human body on the antenna performance. It is designed on a felt substrate, whereas Aaronia-shield conductive textile is utilized as its conductive parts (radiator, shorting wall and ground plane). The antenna performance are studied in two cases, first in free space and then in bent conditions in the close proximity to the human body. The influence of the relative humidity on the textile antenna performance is also investigated numerically. Simulated and measured results indicated good agreements. Finally, the proposed antenna is integrated with a transceiver module and evaluated on the body in practice. Its wireless link quality is assessed in an indoor laboratory.

E-textiles prototypes and applications on wearable devices

This scientific research has the purpose of studying conductive textiles, also known as "smart" textiles. At the ending of the study, we performed the assembly of functional prototypes to give the technology proof of concept to further studies. Between these prototypes are the "smart" jacket, the "smart" pillow, and the "smart" t-shirt. All of these prototypes have electronic devices integrated with conductive textile fabrics and yarns. The functionality of the prototypes involves the obtained vital signals from the user's body, such as heartbeat, and identification of the "touch" made by the user's hand to send commands to a computer or a cellphone screen.

Development of a Screen-Printable Carbon Paste to Achieve Washable Conductive Textiles

Conductive tracks are key constituents of wearable electronics and e-textiles, as they form the interconnective links between wearable electrical devices/systems. They are made by coating or printing conductive patterns or tracks on textiles or by weaving, knitting, or embroidering conductive yarns into textiles. Screen printing is a mature and cost-effective fabrication method that is used in the textile industry. It allows a high degree of geometric freedom for the design of conductive patterns or tracks. Current screen-printed conductive textiles have the limitations of low durability when washed or when placed under bending, and they typically require encapsulation layers to protect the printed conductor. This paper presents a printable paste formulation and fabrication process based on screen printing for achieving a flexible and durable conductive polyester–cotton textile using an inexpensive carbon as the conductor. The process does not require an interface, the smoothing of the textile, or an encapsulation layer to protect the conductor on the textile. A resistivity of 4 × 10−2 Ω·m was achieved. The textile remains conductive after 20 standard washes, resulting in the conductor’s resistance increasing by 140%. The conductive textile demonstrated less than ±10% resistance variation after bending for 2000 cycles.

Electrically Conductive Textile Materials—Application in Flexible Sensors and Antennas

This paper reviews some prominent applications and approaches to developing smart fabrics for wearable technology. The importance of flexible and electrically conductive textiles in the emerging body-centric sensing and wireless communication systems is highlighted. Examples of applications are discussed with a focus on a range of textile-based sensors and antennas. Developments in alternative materials and structures for producing flexible and conductive textiles are reviewed, including inherently conductive polymers, carbon-based materials, and nano-enhanced composite fibers and fibrous structures.

Noncontact ECG Monitoring by Capacitive Coupling of Textiles in a Chair

Some patients are uncomfortable with being wired to a device to have their heart activity measured. Accordingly, this study adopts a noncontact electrocardiogram (ECG) measurement system using coupled capacitance in a conductive textile. The textiles can be placed on a chair and are able to record some of the patient’s heart data. Height and distance between the conductive textile electrodes were influential when trying to obtain an optimal ECG signal. A soft and highly conductive textile was used as the electrode, and clothing was regarded as capacitance insulation. The conductive textile and body were treated as the two electrode plates. This study found that placing the two conductive textiles at the same height provided better data than different heights. The system also enabled identifying the P, Q, R, S, and T waves of the ECG signal and eliminated unnecessary noise successfully.

Multi-Point Flexible Temperature Sensor Array and Thermoelectric Generator Made from Copper-Coated Textiles

The integration of electrical functionality into flexible textile structures requires the development of new concepts for flexible conductive material. Conductive and flexible thin films can be generated on non-conductive textile materials by electroless metal deposition. By electroless copper deposition on lyocell-type cellulose fabrics, thin conductive layers with a thickness of approximately 260 nm were prepared. The total copper content of a textile fabric was analyzed to be 147 mg per g of fabric, so that the textile character of the material remains unchanged, which includes, for example, the flexibility and bendability. The flexible material could be used to manufacture a thermoelectric sensor array and generator. This approach enables the formation of a sensor textile with a large number of individual sensors and, at the same time, a reduction in the number of electrical connections, since the conductive textile serves as a common conductive line for all sensors. In combination with aluminum, thermoelectric coefficients of 3–4 µV/K were obtained, which are comparable with copper/aluminum foil and bulk material. Thermoelectric generators, consisting of six junctions using the same material combinations, led to electric output voltages of 0.4 mV for both setups at a temperature difference of 71 K. The results demonstrate the potential of electroless deposition for the production of thin-film-coated flexible textiles, and represent a key technology to achieve the direct integration of electrical sensors and conductors in non-conductive material.