Textile Patch Research Articles

Low-profile robust circularly polarized textile patch antenna for WBAN and ISM applications

In this research, a conformal circularly polarized (CP) antenna has been developed employing polyester textile as its substrate material. The proposed antenna configuration demonstrates its efficacy across multiple frequency bands—specifically 3 GHz and 4.5 GHz of WBAN and 5.8 GHz of ISM radio bands. The antenna’s distinctive design is developed on a rectangular plane as its primary radiating component, with a ground structure ingeniously arranged counter-positioning to the antenna’s patch. Electrical conductivity was widely achieved by employing adhesive copper and silver tape, conductive fabric, stitching conductive threads and copper paint, conventionally applied through brush painting techniques. The copper paint fabrication methodology has been chosen for its ability to confer conformability upon the antenna while minimizing its dimensions, ensuring lightweight attributes, and endowing it with remarkable resilience to environmental factors while preserving its optimal radiating performance. The CP polyester antenna showcases noteworthy peak gains: 3.91 dBi at 3 GHz, 5.86 dBi at 4.5 GHz and 6.62 dBi at 5.8 GHz (ISM). These gains highlight the antenna’s ability to efficiently capture and transmit signals within the aforementioned frequency bands, affirming its potential for robust wireless communication.

Embedding textile capacitive sensing into smart wearables as a versatile solution for human motion capturing

This work presents a novel and versatile approach to employ textile capacitive sensing as an effective solution for capturing human body movement through fashionable and everyday-life garments. Conductive textile patches are utilized for sensing the movement, working without the need for strain or direct body contact, wherefore the patches can sense only from their deformation within the garment. This principle allows the sensing area to be decoupled from the wearer’s body for improved wearing comfort and more pleasant integration. We demonstrate our technology based on multiple prototypes which have been developed by an interdisciplinary team of electrical engineers, computer scientists, digital artists, and smart fashion designers through several iterations to seamlessly incorporate the technology of capacitive sensing with corresponding design considerations into textile materials. The resulting accumulation of textile capacitive sensing wearables showcases the versatile application possibilities of our technology from single-joint angle measurements towards multi-joint body part tracking.

A reflective textile metasurface for indoor signal coverage enhancement

The design of a reflective metasurface solely based on flexible textile material is presented for indoor signal coverage enhancement in a specific scenario – reflecting and reallocating radio frequency energy that would have leaked through a large window area. The proposed reflective metasurface design, reflective metasurface is composed of layers of square conductive textile patches and dielectric textile substrates. For the unit cell design, a reflective phase difference of up to 90° can be achieved via varying the size of the conductive patches. Meanwhile, a phase difference of up to 180° can be achieved by the alignment of conductive patches on different textile substrate layers, which is an ideal design philosophy for textile material. The proposed metasurface, consisting of 12 × 12 unit cells, can achieve a main reflected beam pointing in the direction of ±35° and a secondary reflected beam at ±63°. Simulated results show that the reflected beams remain relatively stable under the crumpling conditions often seen for curtains. A prototype of the design was fabricated and tested in a real-world scenario. A maximum signal strength enhancement of 15 dB and an average enhancement of 5.97 dB in a wide range of directions can be achieved with the reflective metasurface applied.

Development of wearable textile patch antenna 2.43 GHz for biomedical applications

Development of wearable textile patch antenna 2.43 GHz for biomedical applications

A Lattice-Hinge-Design-Based Stretchable Textile Microstrip Patch Antenna for Wireless Strain Sensing at 2.45 GHz.

The manuscript presents a novel approach to designing and fabricating a stretchable patch antenna designed for strain sensing and the wireless communication of sensing data at the same time. The challenge lies in combining flexible and stretchable textile materials with different physical morphologies, which can hinder the adhesion among multiple layers when stacked up, resisting the overall stretchability of the antenna. The proposed antenna design overcomes this challenge by incorporating a lattice hinge pattern into the non-stretchable conductive e-textile, transforming it into a stretchable structure. The innovative design includes longitudinal cuts inserted in both the patch and the ground plane of the antenna, allowing it to stretch along in the perpendicular direction. Implementing the lattice hinge pattern over the conductive layers of the proposed patch antenna, in combination with a 2 mm thick Polydimethylsiloxane (PDMS) substrate, achieves a maximum of 25% stretchability compared to its counterpart antenna without a lattice hinge design. The stretchable textile antenna resonates around a frequency of 2.45 GHz and exhibits a linear resonant frequency shift when strained up to 25%. This characteristic makes it suitable for use as a strain sensor. Additionally, the lattice hinge design enhances the conformability and flexibility of the antenna compared to that of a solid patch antenna. The realized antenna gains in the E and H-plane are measured as 2.21 dBi and 2.34 dBi, respectively. Overall, the presented design offers a simple and effective solution for fabricating a stretchable textile patch antenna for normal use or as a sensing element, opening up possibilities for applications in the communication and sensing fields.

Investigation of the Bonding Mechanism between Overlapping Textile Layers for FRP Repair Based on Dry Textile Patches.

Lots of damaged fiber-reinforced plastic (FRP) components are replaced by new components instead of repairing. Furthermore, only very labor-intensive repair methods are available on the market to fully restore the integrity of the structure. This requires a high level of experience or, alternatively, very cost-intensive technology, such as the use of computer tomography and robotics. The high costs and CO2 emissions caused by the manufacture of FRP components then bear no relation to their service life. The research project IGF-21985 BR "FRP-Repair" aims to solve the named challenges. Using semiconductor oxide catalysts, the matrix can be locally depolymerized by ultraviolet (UV) radiation, and thus removed from the damaged area of the FRP component. Subsequently, the damaged fibers in this area can be detached. By using customized textile repair patches and local thermoset reinfiltration, the repair area is restored. With this process, the fiber structure can be repaired locally with new fibers on the textile level. The repair is similar to the original production of a fiber composite in an infusion process. No additional adhesive material is used. As a result, repaired FRP structures with restored mechanics and a near-original surface can be realized. This article provides an insight into the actual steps of the development of the FRP component repair process using dry textile patches. The empirical investigation of overlapped rovings and UD material showed the expected results. Residual fracture forces of up to 86% could be achieved. The most interesting approach on the roving level was splicing the overlapping fibers. The free ends of the fibers of the patch and part are mechanically bonded. This bond at the textile level is further strengthened by infusion with matrix.

Anthraquinone-Polyaniline-Integrated Textile Platforms for In Situ Electrochemical Production of Hydrogen Peroxide for Microbial Deactivation.

Hydrogen peroxide (H2O2) is a versatile and effective disinfectant against common pathogenic bacteria such as Escherichia coli (E. coli). Electrochemical H2O2 generation has been studied in the past, but a lack of studies exists on miniaturized electrochemical platforms for the on-demand synthesis of H2O2 for antibacterial applications. In this article, a chemically modified cotton textile platform capable of in situ H2O2 production is demonstrated for E. coli deactivation. The cotton textile was modified by layer-by-layer coating with conductive carbon nanotubes/cellulose nanocrystals (CNT/CNC) and a polymer of polyaniline (PANI) decorated with anthraquinone (AQ), designated as the AQ@PANI@CNT/CNC@textile antibacterial patch. The AQ@PANI@CNT/CNC@textile antibacterial textile patch H2O2 production capabilities were evaluated using both electrochemical and colorimetric methods. The AQ@PANI@CNT/CNC@textile antibacterial patch electrochemically produced H2O2 concentrations up to 209 ± 25 µM over a 40 min period and displayed a log reduction of 3.32 for E. coli over a period of 2 h. The AQ@PANI@CNT/CNC@textile antibacterial patch offers promise for use as a self-disinfecting pathogen control platform.

Multifunctional Fiber for Synchronous Bio‐Sensing and Power Supply in Sweat Environment

AbstractContinuous monitoring of human sweat, which enables highly sensitive multiple biomarkers analysis with a portable power supply, is increasingly desired for the remote healthcare industry. Smart fibers with on‐demand functionality are ideal candidates for fabricating noninvasive and conformal bioelectronic devices owing to their considerable flexibility. Herein, a multifunctional textile patch based on a reduced graphene oxide (rGO)/tetra‐aniline (TANi) fiber for simultaneous biomarker monitoring and energy supply is reported. Benefiting from the multi‐electrochemical redox states and proton doping/dedoping characteristics of TANi, rGO/TANi hybrid fibers are combined into an energy storage device and biosensor in a physiological environment. GO flakes increase the viscoelasticity of the wet‐spinning dope by regulating the noncovalent interactions between TANi aggregates, thereby enhancing the mechanical strength and conductivity of the resulting rGO/TANi hybrid fiber. Consequently, the hybrid fiber exhibits high volumetric capacitance and versatile sensing capability for various physiological analytes, e.g., pH, K+, and glucose in sweat electrolyte. Furthermore, a wireless continuous sweat monitoring system is constructed by integrating the multifunctional fiber sensor into a printed electric circuit board with programmed functionality. Such a delicate integrated design that harnesses the signal collection and communication units is anticipated to facilitate practical applications in personalized diagnostic and physiological health.

Wearable Rectenna With Integrated Miniaturized Feeding Slot and Rectifier Structure

A low-cost hybrid textile/PCB wearable rectenna is designed for smart on-body applications. It is an integration of a textile patch antenna and a highly efficient rectifier on a small PCB substrate, where the feeding aperture of the antenna is significantly miniaturized by exploiting an LC loading technique in order to have an effective integration with the rectifier. The feeding-rectifying circuitry is attached to the back of the antenna by normal sewing threads. The essential components are soldered on the small rigid PCB for a robust connection. The size of the rectenna is 0.817 × 0.817 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while the rigid substrate area for the feeding-rectifying circuitry is only 0.278 × 0.147 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (3.4 cm × 1.8 cm) at 2.45 GHz. The intrinsic dielectric/conduction loss of textile feedlines, the loss of antenna-to-rectifier interconnectors, the loss of soldering or gluing on textiles, and the loss due to body absorption from typical large feeding slots are constitutively reduced. The soldering points and the consequent hard-to-be-characterized parasitic effects on textiles are avoided. The proposed integration approach reduces the cost and eases the rectenna design, fabrication, and integration. As a result, the power conversion efficiency (PCE) of the rectifier reaches up to 39.5% at -20 dBm input power level whilst the experimental rectenna prototype achieves the state-of-the-art PCE of 41% at an extremely low incident power density of 0.4 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The maximum PCE is 56% at the -5 dBm input power. Finally, the possibility of harvesting datalink energy from PC/mobile phones as power source for wearable electronics is investigated.

Wearable Textile Patch Antenna: Challenges and Future Directions

Wearable antennas have grown in popularity in recent years as a result of their appealing features and prospects to actualize lightweight, compact, low-cost and adaptable wireless communications and surroundings. These antennas have to be conformal and made of lightweight materials in a low-profile arrangement when attached to various parts of the human body. Near-body operation of these antennas should be possible without degradation. When these characteristics are taken into account, the layout of wearable antennas become challenging, especially when textile substrates are investigated, high conductivity materials are used during manufacturing procedures and body binding scenarios have an impact on the design’s performance. Several of these issues arise in the context of body-worn deployment, despite modest changes in magnitude between implementations. This paper examines the multiple issues and obstacles encountered in the construction of wearable antennas as well as the range of materials used, and the Specific Absorption Rate (SAR) effects employed as well as the bending scheme. An overview of the innovative features and their separate approaches to addressing the difficulties lately raised by work in this field conducted by the scientific community is provided as an appendix.

Integrated in Clothes Graphene Antenna with Low SAR for Wearable Body-Centric Communications

The design and fabrication of graphene based textile patch antennas, intended for use in the 2.45GHz ISM band, are presented. The antennas have simple geometries with rectangular, triangular, or circular shape and substrate materials made of four different fabrics suitable for wearable applications. Conductive graphene sheet is used for the active element patches of the twelve different proposed prototypes. The effects of the antenna geometry, the substrate selection and the graphene-textile fabrication process on the prototypes’ performance are studied. Several prototypes exhibit desirable characteristics, such as high gain, acceptable radiation pattern, low Specific Absorption Rate (SAR), relatively wide bandwidth, and coverage of the ISM band even under different bending conditions.

Wearable Textile Antenna with a Graphene Sheet or Conductive Fabric Patch for the 2.45 GHz Band

Textile patch antennas of simple rectangular, triangular, and circular shape, for operation in the 2.4–2.5 GHz free industrial, scientific, and medical (ISM) band, are designed in this paper. Thirty-six patch antenna prototypes have been fabricated by engaging different patch geometries, patch materials, and substrate materials. Each patch antenna is designed after optimization by a genetic algorithm, which evolves the initial dimensions and feeding position of the prototype’s microstrip counterpart to the final optimal geometrical characteristics of the wearable prototype (with the originally selected shape and materials). The impact of the design and fabrication details on antenna performance were thoroughly investigated. Graphene sheet patches were tested against conductive fabric and copper sheet ones, while denim and felt textile substrates were competing. The comparative study between a large number of different graphene, all, and copper textile prototypes, which revealed the excellent suitability of graphene for wearable applications, is the main contribution of this paper. Additional novelty elements are the compact, flexible, and easy-to-fabricate structure of the proposed antennas, as well as the use of state-of-the-art conductive materials and commercially available fabrics and the extensive investigation of many prototypes in various bending conditions. Simulations and measurements of the proposed antennas are in very good agreement. All fabricated prototypes are characterized by flexibility, light weight, mechanical stability, resistance to shock, bending and vibrations, unhindered integration to clothes, low-cost implementation, simple, time-saving, and industry-compatible fabrication process, and low specific absorption rate (SAR) values (computed using rectangular and voxel models); the graphene prototypes are additionally resistant to corrosion, and the circular ones have very good performance under bending conditions. Many antenna prototypes demonstrate interesting characteristics, such as relatively wide bandwidth, adequate gain, firm radiation patterns, coverage of the ISM band even under bending, and very low SAR values. For example, the circular graphene patch (with 55.3 mm diameter attached upon a 165.9 × 165.9 mm) felt substrate CGsF1 prototype accomplishes 109 MHz measured bandwidth, 5.45 dBi gain, 56% efficiency, full coverage of the ISM band under bending, and SAR less than 0.003 W/Kg.

2 × 2 Textile Rectenna Array with Electromagnetically Coupled Microstrip Patch Antennas in the 2.4 GHz WiFi Band

The development of e-textiles is fostering research in wireless energy transmission. This paper presents a purely textile 2.4 GHz WiFi band 2 × 2 rectenna array for RF energy harvesting. It utilizes the electromagnetically coupled microstrip patch antenna topology and a simple and precise construction method that provides a good performance repeatability to create multilayer microstrip textile patch antennas. The rectifier is implemented with Schottky diodes and it takes the voltage doubling configuration. An average DC power of 1,1 mW was measured for 14 μW/cm2 of RF input power density, while the end-to-end average power conversion efficiency (PCE) measured was 31%. The characterization of the end-to-end PCE was evaluated considering the physical size of the prototype to make the comparison with other designs easier. Measurements in a real WiFi scenario were also performed, demonstrating its feasibility for feeding e-textiles.

Textile-Based Stretchable Microstrip Antenna with Intrinsic Strain Sensing.

This paper presents a textile-based stretchable microstrip patch antenna with intrinsic strain for e-textiles with seamlessly integrated multifunctional devices. Several microstrip antennas have been developed with the patch alone (stretchable up to 40%) or both the patch and the ground plane (stretchable up to 100%) meshed by using rectangular serpentine units. The changes in the resonant frequency of the meshed antennas, as a result of stretching, have been exploited to demonstrate the intrinsic uniaxial strain sensing. The obtained results indicate that resonant frequency decreases linearly with increasing applied strain, suggesting that the designed antennas can also be used as strain sensors with stretchability up to 100% and a sensitivity of 0.25. The results were validated through full-wave electromagnetic simulations and a two-dimensional digital image correlation (DIC) technique to model the antenna deformations during the tensile tests. In terms of stretchability, the meshed textile patch antenna on a solid ground plane showed more than a 2-fold improvement compared to a meshed gold patch antenna, showing a linear frequency shift. As potential applications, we demonstrate the use of a highly deformable fully meshed textile antenna as a strain sensor capable of measuring joint angles of a human limb. To do that, a microwave readout circuit based on RF to DC rectifier was realized. The rectifier obtained a peak conversion efficiency of 71% at 10 dBm input power overload resistor of 3 kΩ.

Broadband coplanar waveguide‐fed stub loaded pot shape E‐textile antenna equipped with perfect electric conductor

In this paper, a coplanar waveguide (CPW) fed pot-shaped electronic textile (E-textile) antenna aided by rectangular ring ground plane has been proposed. The textile patch in pot form is designed by cutting triangular slots on the non-radiating edges of the rectangular patch, which yields a broadband of 6.45 GHz. The measured antenna impedance bandwidth is from 2.15 to 8.6 GHz with a peak gain of 10.7 dB on fabricated human tissue muscle equivalent phantom model. The proposed antenna exhibits a broadside radiation pattern from 2.15 GHz to less than 6 GHz and conical radiation pattern from 6 GHz to 8.6 GHz covering wide impedance matching bandwidth (S11 ≤ −10 dB) of 120% for dual-mode off and on-body communication. In CPW fed technique, the back radiation from the antenna to on body is reduced by using a perfect electric conductor. For wearable applications, considering human safety concern the specific absorption rate levels are maintained, that is less than 1.6 W/kg limit over the operating bandwidth according to IEEE C95.1-1999 standard averaged over 1 g of tissue model.

Breathable Textile Rectangular Ring Microstrip Patch Antenna at 2.45 GHz for Wearable Applications.

A textile patch antenna is an attractive package for wearable applications as it offers flexibility, less weight, easy integration into the garment and better comfort to the wearer. When it comes to wearability, above all, comfort comes ahead of the rest of the properties. The air permeability and the water vapor permeability of textiles are linked to the thermophysiological comfort of the wearer as they help to improve the breathability of textiles. This paper includes the construction of a breathable textile rectangular ring microstrip patch antenna with improved water vapor permeability. A selection of high air permeable conductive fabrics and 3-dimensional knitted spacer dielectric substrates was made to ensure better water vapor permeability of the breathable textile rectangular ring microstrip patch antenna. To further improve the water vapor permeability of the breathable textile rectangular ring microstrip patch antenna, a novel approach of inserting a large number of small-sized holes of 1 mm diameter in the conductive layers (the patch and the ground plane) of the antenna was adopted. Besides this, the insertion of a large number of small-sized holes improved the flexibility of the rectangular ring microstrip patch antenna. The result was a breathable perforated (with small-sized holes) textile rectangular ring microstrip patch antenna with the water vapor permeability as high as 5296.70 g/m2 per day, an air permeability as high as 510 mm/s, and with radiation gains being 4.2 dBi and 5.4 dBi in the E-plane and H-plane, respectively. The antenna was designed to resonate for the Industrial, Scientific and Medical band at a specific 2.45 GHz frequency.

A Systematic Study of Wearable Multi-Modal Capacitive Textile Patches

We present a study on wearable capacitive patches with engineered dielectrics to be used as a strain sensor and a piezoelectric sensor with multi-modal sensing capabilities. The patches consist of a parallel plate capacitive structure with highly (100%) stretchable textile electrodes and silicone or PDMS elastomers. The gauge factor of the capacitive strain sensor is enhanced two-fold with the inclusion of high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> Barium Titanate (BTO) nanoparticles dispersed in the silicone dielectric layer without sacrificing their excellent linearity or superb durability easily exceeding 2000 cycles. In addition to enhanced dielectric response, inclusion of BTO as well as other additives, namely PZT and PVDF-TrFE, in PDMS also induces piezoelectricity in the sensors at different weight ratios systematically studied by bending and vibrational tests. Corona poling of the piezo dielectrics improves their voltage output by at least two folds. Besides the piezoelectricity, tests on unpoled samples also uncovered evidence for triboelectricity in the nanocomposites. The proposed textile patches can simultaneously detect multiple stimuli such as strain, pressure, temperature, bending, vibration, and acoustic feedback. Deployed in appropriate locations and geometries, the patches can capture critical information on the type, strength, and duration between episodic movements and environmental factors, as demonstrated via a shoe-insert, elbow tracker, respiratory and heart-rate monitors. Accordingly, capacitive textile patches offer unique capabilities for multi-modal sensing in biomedical and robotic applications as well as overall system integration that are advantageous for sensor fusion and machine learning.

Gain enhancement by utilizing hexagonal reflector based optimized textile antenna

In this article, a square patch antenna with reflector is fed by inset feed for wearable applications in the ISM band (2.45 GHz) Using Jean's substrate with a 3 mm thickness and dielectric constant of 1.7. In this article, the design of the Textile patch antenna is optimized using the Oppositional Particle Swarm optimization (OPSO) algorithm to resonate at 2.45 GHz. The PSO is a population-based algorithm designed to tackle various optimization problems. The performance deteriorates significantly when the optimization problems are to be subject to noise . The flexible and textile antennas have taken a lot of attention due to their application in wearable systems and their testing in real-work conditions. The major advantage of the proposed system is minimizing the back lobe and enhances the gain. Usually, Antenna parameters such as reflection coefficient, Voltage standing wave ratio, Gain & Directivity are measured using CST software.

Wearable textile EBG‐inspired bandwidth‐enhanced patch antenna

An electromagnetic bandgap (EBG)-inspired low-profile wideband textile antenna is presented. By partially surrounding a standard textile patch antenna with mushroom EBG cells, a significant enhancement of the 10 dB impedance bandwidth is obtained. In particular, whereas a standard textile patch antenna exhibits a typical 10 dB bandwidth of 6% for a substrate thickness of 0.04, the proposed technique extends the 10 dB impedance bandwidth to 32%. Notably, the relatively large impedance bandwidth is achieved without extracting a heavy cost in terms of fabrication or design complexity. To make the design amenable for textile implementation, as opposed to more conventional designs which use EBG cells as a replacement for a ground plane, the proposed design hinges on the patch antenna being coplanar with a single quasi-ring of coplanar EBG cells. The proposed antenna design is validated through measurements in free space and on-body, where it is demonstrated to be robust to the effects of bending in the two principal planes.

Use of conductive zip and Velcro as a polarisation reconfiguration means of a textile patch antenna

Α feasibility study of using components such as conductive Velcro tape and zip fastener to change the polarisation of a textile patch antenna from linear (LP) to circular (CP) is presented. The antennas are designed to operate at 2.3–2.5 GHz frequency band, are made using felt substrate and conductive cloth and their size is 100.4 mm × 74.2 mm × 4.26 mm. It is proved, via simulations and measurements, that such components are strong candidates as means for polarisation reconfiguration of textile antennas. Both Velcro and zip textile patch antennas at the LP mode yield axial ratio (AR) larger than 10 dB at the operating frequency range. In the CP mode, the Velcro antenna gives AR equal to 3.1 dB at 2.35 GHz and the zip antenna 1 dB at 2.31 GHz. Repeatability measurements of interchanging polarisation modes (LP–CP) for both antennas have been conducted presenting acceptable repeatability. Great advantage of both antennas (Velcro and zip) is that the polarisation can be changed at will by a simple manipulation (detach the Velcro or unzip); thus, providing to the user the flexibility of adjusting the antenna characteristics depending on wearable application and environment of operation.