Wearable, Knitted 3D Spacer Thermoelectric Generator with Detachable p-n Junctions for Body Heat Energy Harvesting.

Textile-based thermoelectric (TE) devices are being investigated to power smart textiles autonomously. While previous research has focused on a solid system where the required junctions are fabricated into the device, there has been limited attention given to replacing these TE systems reliably. This work looks at a newer approach to the construction and demonstration of a wearable thermoelectric structure that employs three-dimensional knitted spacers to increase the temperature difference where the TE junctions are detachable and disposable. This system features positive and negative junctions which can be removed while maintaining its excellent voltage generation in low ΔT and good Seebeck coefficients. A mathematical model simulates the potential energy outputs and maximum power points generated, which can be used to increase the device's performance for future wearable sensing applications.

The impact of knitted linked seams on comfort and friction perception.

Friction from knitted clothing can cause discomfort and skin issues, underscoring the importance of tactile comfort for wearers. Seamless knitted garments are assumed to be comfortable to wear, yet there is little understanding of their tactile comfort in comparison to linked seams - the most common form of knitted garment. This novel study examines the influence of a garments knitted structural architecture on clothing comfort and wearability by investigating skin friction and tactile perception across ten body regions in both male and female participants, using two commonly utilised materials and seam designs: cotton and merino wool with plain and linked seams. The impact of seam design and regional factors on skin friction and tactile perception was analysed, revealing varying levels across tested body regions. Removing seams exposed a greater surface area to skin contact, leading to higher perceived friction levels. As such, structural elements in knitted garments enhance wearer comfort.

Seamless knitwear manufacturing offers a more environmentally conscious option compared to traditional cut-and-sew processes. This study investigated the impact of knitted garment material and structure on wearer comfort by analysing skin friction and tactile perception across ten upper body regions. Removing seams increased garment-to-skin contact leading to wearer discomfort.

A Novel Force-Sensing Smart Textile: Inserting Silicone-Embedded FBG Sensors into a Knitted Undergarment.

A number of textile-based fiber optic sensors have recently been proposed for the continuous monitoring of vital signs. However, some of these sensors are likely unsuitable for conducting direct measurements on the torso as they lack elasticity and are inconvenient. This project provides a novel method for creating a force-sensing smart textile by inlaying four silicone-embedded fiber Bragg grating sensors into a knitted undergarment. The applied force was determined within 3 N after transferring the Bragg wavelength. The results show that the sensors embedded in the silicone membranes achieved enhanced sensitivity to force, as well as flexibility and softness. Additionally, by assessing the degree of FBG response to a range of standardized forces, the linearity (R2) between the shift in the Bragg wavelength and force was found to be above 0.95, with an ICC of 0.97, when tested on a soft surface. Furthermore, the real-time data acquisition could facilitate the adjustment and monitoring of force during the fitting processes, such as in bracing treatment for adolescent idiopathic scoliosis patients. Nevertheless, the optimal bracing pressure has not yet been standardized. This proposed method could help orthotists to adjust the tightness of brace straps and the location of padding in a more scientific and straightforward way. The output of this project could be further extended to determine ideal bracing pressure levels.

Impact of quantification method on microfiber assessment - A comparative analysis between mass and count based methods.

Microfiber from textiles is one of the new anthropogenic pollutants which attracted a wide range of researchers. Domestic laundry, being the most common cause of microfiber release from textiles, is widely studied. Studies exhibit a broad range of quantities of microfibers owing to the distinct quantification methodologies employed due to their convenience and resource availability. Out of several such estimation processes, reporting microfiber quantity in numbers or mass (mg or g) is quite common with respect to the unit area or weight of the textile used. However, results reported by different literature vary significantly. Hence, this study aims to analyze the microfiber release from knitted polyester fabric using count- and mass-based methods. Four different fabrics were used for this study with three different counting processes from literature along with direct weight difference estimation. The results of the direct counting method showed that the average microfiber release of selected fabrics is 13.28-33.16 microfibers per sq.cm, whereas, the direct weight estimation showed an average weight of 0.0664 ± 0.0289 mg/sq.cm. The subsequent conversion showed a release of 887.89 ± 633.49 microfibers/sq.cm of the fabric. Further, the microfiber mass was also estimated using the number of microfiber count and found that a sq.cm of fabric releases up to 0.0010-0.0024 mg of microfibers. While comparing the results, the weight-based estimation showed a significantly higher microfiber release (41.3-42.9 times) than the direct counting method. The deposition of surfactants in detergents, contaminants from the water, atmospheric contaminants, and finishes released from the fabric can be the sources of additional weights noted in the direct mass estimation. As the weight-based method is quite simple and the fastest way to quantify the microfibers, future studies must focus on this area to reduce the error percentage in quantification.

Development of Low Hysteresis, Linear Weft-Knitted Strain Sensors for Smart Textile Applications.

In recent years, knitted strain sensors have been developed that aim to achieve reliable sensing and high wearability, but they are associated with difficulties due to high hysteresis and low gauge factor (GF) values. This study investigated the electromechanical performance of the weft-knitted strain sensors with a systematic approach to achieve reliable knitted sensors. For two elastic yarn types, six conductive yarns with different resistivities, the knitting density as well as the number of conductive courses were considered as variables in the study. We focused on the 1 × 1 rib structure and in the sensing areas co-knit the conductive and elastic yarns and observed that positioning the conductive yarns at the inside was crucial for obtaining sensors with low hysteresis values. We show that using this technique and varying the knitting density, linear sensors with a working range up to 40% with low hysteresis can be obtained. In addition, using this technique and varying the knitting density, linear sensors with a working range up to 40% strain, hysteresis values as low as 0.03, and GFs varying between 0 and 1.19 can be achieved.

Slot Antennas Integrated into 3D Knitted Fabrics: 5.8 GHz and 24 GHz ISM Bands.

In the paper, a 3D knitted fabric is used for the design of a circularly polarized textile-integrated antenna. The role of the radiating element is played by a circular slot etched into the conductive top wall of a textile-integrated waveguide. Inside the circular slot, a cross slot rotated for about 45° is etched to excite the circular polarization. The polarization of the antenna can be changed by the rotation of the cross slot. The antenna has a patch-like radiation pattern, and the gain is about 5.3 dBi. The textile-integrated feeder of the antenna is manufactured by screen printing conductive surfaces and sewing side walls with conductive threads. The antenna was developed for ISM bands 5.8 GHz and 24 GHz. The operation frequency 24 GHz is the highest frequency of operation for which the textile-integrated waveguide antenna has been manufactured.

A Mass-Producible Washable Smart Garment with Embedded Textile EMG Electrodes for Control of Myoelectric Prostheses: A Pilot Study.

Electromyography (EMG) is the resulting electrical signal from muscle activity, commonly used as a proxy for users' intent in voluntary control of prosthetic devices. EMG signals are recorded with gold standard Ag/AgCl gel electrodes, though there are limitations in continuous use applications, with potential skin irritations and discomfort. Alternative dry solid metallic electrodes also face long-term usability and comfort challenges due to their inflexible and non-breathable structures. This is critical when the anatomy of the targeted body region is variable (e.g., residual limbs of individuals with amputation), and conformal contact is essential. In this study, textile electrodes were developed, and their performance in recording EMG signals was compared to gel electrodes. Additionally, to assess the reusability and robustness of the textile electrodes, the effect of 30 consumer washes was investigated. Comparisons were made between the signal-to-noise ratio (SNR), with no statistically significant difference, and with the power spectral density (PSD), showing a high correlation. Subsequently, a fully textile sleeve was fabricated covering the forearm, with 14 textile electrodes. For three individuals, an artificial neural network model was trained, capturing the EMG of 7 distinct finger movements. The personalized models were then used to successfully control a myoelectric prosthetic hand.

A Knitted Sensing Glove for Human Hand Postures Pattern Recognition.

In recent years, flexible sensors for data gloves have been developed that aim to achieve excellent wearability, but they are associated with difficulties due to the complicated manufacturing and embedding into the glove. This study proposes a knitted glove integrated with strain sensors for pattern recognition of hand postures. The proposed sensing glove is fabricated at all once by a knitting technique without sewing and bonding, which is composed of strain sensors knitted with conductive yarn and a glove body with non-conductive yarn. To verify the performance of the developed glove, electrical resistance variations were measured according to the flexed angle and speed. These data showed different values depending on the speed or angle of movements. We carried out experiments on hand postures pattern recognition for the practicability verification of the knitted sensing glove. For this purpose, 10 able-bodied subjects participated in the recognition experiments on 10 target hand postures. The average classification accuracy of 10 subjects reached 94.17% when their own data were used. The accuracy of up to 97.1% was achieved in the case of grasp posture among 10 target postures. When all mixed data from 10 subjects were utilized for pattern recognition, the average classification expressed by the confusion matrix arrived at 89.5%. Therefore, the comprehensive experimental results demonstrated the effectiveness of the knitted sensing gloves. In addition, it is expected to reduce the cost through a simple manufacturing process of the knitted sensing glove.

Load-deformation behaviour of weft-knitted textile reinforced concrete in uniaxial tension.

Weft-knitted textiles offer many advantages over conventional woven fabrics since they allow the fabrication of doubly curved geometries without the need of stitching multiple patches together. This study investigated the use of high-strength continuous fibres as knitted textile reinforcement, focusing on various knitting patterns, fibre materials, coating types and spatial features to enhance the bond conditions between concrete and reinforcement. The bond is of particular interest since the contact surface of knitted textiles is fundamentally different due to their closed surface, compared to commercially available textile reinforcement, which is normally formed as orthogonally woven grids of rovings. An experimental campaign consisting of 28 textile-concrete composites was conducted, where digital image correlation-based measurements were used to assess the load-deformation behaviour and to analyse the crack kinematics. The results showed a beneficial post-cracking behaviour for epoxy coated configurations with straight inlays. The comparison of these configurations with conventional textile reinforcement generally showed a similar behaviour, but with higher utilisation compared to the filament strength. The Tension Chord Model, which assumes a constant bond stress-slip relationship, was adapted for the specific geometry of the knitted reinforcement, and it was used for the estimation of bond stresses and a post-diction of the experimental results, generally showing a good agreement.

Evaluation of Effectiveness of Three New Gingival Retraction Systems: A Comparative Study.

AIM: To analyze the clinical effectiveness of three new gingival retraction systems: knitted retraction cord, expanding polyvinyl siloxane, and aluminium chloride containing paste. MATERIALS AND METHODS: Twenty patients were enrolled with age-group of more than 18 years and who required fixed prosthesis with minimum of two abutments. A preliminary impression of the arch was made with a stock metal tray and irreversible hydrocolloid impression material. Group WR-impression without retraction, Group A-impression after retraction with gingival retraction cord, Group B-impression after retraction with expanding polyvinyl siloxane, and Group C-impression after retraction with aluminium chloride containing paste. A total of four impressions were made for each abutment tooth. Each impression was given a label 1WR, 1A, 1B, 1C-20WR, 20A, 20B, 20C: where 1 denoted the sample number. Comparison of the stereomicroscopic images was done using image analysis software. Time required from start of placement of gingival displacement agents till completion was recorded in seconds with the help of a stop clock. RESULTS: The mean gingival retraction was found to be the highest for subjects of Group C followed by Group A, Group B, and Group WR. This difference was found to be statistically significant. Highly significant mean difference in time of placement was observed between Group A and Group B, between Group B and Group C, and between Group C and Group A. CONCLUSION: The aluminium chloride containing paste was found effective in almost all the variables considered. CLINICAL SIGNIFICANCE: The choice of particular gingival retraction system/technique is dependent upon the clinical variables and on operator's preference.

Performance Evaluation of Knitted and Stitched Textile Strain Sensors.

By embedding conductive yarns in, or onto, knitted textile fabrics, simple but robust stretch sensor garments can be manufactured. In that way resistance based sensors can be fully integrated in textiles without compromising wearing comfort, stretchiness, washability, and ease of use in daily life. The many studies on such textile strain sensors that have been published in recent years show that these sensors work in principle, but closer inspection reveals that many of them still have severe practical limitations like a too narrow working range, lack of sensitivity, and undesired time-dependent and hysteresis effects. For those that intend to use this technology it is difficult to determine which manufacturing parameters, shape, stitch type, and materials to apply to realize a functional sensor for a given application. This paper therefore aims to serve as a guideline for the fashion designers, electronic engineers, textile researchers, movement scientists, and human-computer interaction specialists planning to create stretch sensor garments. The paper is limited to textile based sensors that can be constructed using commercially available conductive yarns and existing knitting and embroidery equipment. Within this subtopic, relevant literature is discussed, and a detailed quantitative comparison is provided focusing on sensor characteristics like the gauge factor, working range, and hysteresis.

Review on Smart Electro-Clothing Systems (SeCSs).

This review paper presents an overview of the smart electro-clothing systems (SeCSs) targeted at health monitoring, sports benefits, fitness tracking, and social activities. Technical features of the available SeCSs, covering both textile and electronic components, are thoroughly discussed and their applications in the industry and research purposes are highlighted. In addition, it also presents the developments in the associated areas of wearable sensor systems and textile-based dry sensors. As became evident during the literature research, such a review on SeCSs covering all relevant issues has not been presented before. This paper will be particularly helpful for new generation researchers who are and will be investigating the design, development, function, and comforts of the sensor integrated clothing materials.

Conversion of CO2 into Chloropropene Carbonate Catalyzed by Iron (II) Phthalocyanine Hypercrosslinked Porous Organic Polymer.

Commercial iron (II) phthalocyanine (FePc) was knitted with biphenyl using a Friedel-Crafts reaction to yield a micro-meso porous organic polymer (FePc-POP) with a specific surface area of 427 m2/g and 5.42% of iron loading. This strategy allowed for the direct synthesis of a heterogeneous catalyst from an iron containing monomer. The catalytic system, formed by the knitted polymer containing FePc and DMAP (4-dimethylamino pyridine) as base, results in an efficient heterogeneous catalyst in the cycloaddition of CO2 to epichlorohydrin to selectively obtain the corresponding cyclic carbonate. Thus, a TON (mmol substrate converted/mmol catalysts used) value of 2700 was reached in 3 h under mild reaction conditions (solvent free, 90 °C, 3 bar of CO2). The catalyst does not exhibit leaching during the reactions, which was attributed to the excellent stability of the metal in the macrocycle.

Human Motion Recognition of Knitted Flexible Sensor in Walking Cycle.

Knitted fabric sensors have been widely used as strain sensors in the sports health field and its large strain performance and structure are suitable for human body movements. When a knitted structure is worn, different human body movements are reflected through the large strain deformation of fabric structure and consequently change the electrical signal. Here, the mechanical and electrical properties of highly elastic knitted sweatpants were tested under large strain. This sensor has good sensitivity and stability during movement. Compared with traditional motion monitoring, this technique divides the walking cycle into two stages, namely, stance and swing phases, which can be further subdivided into six stages. The corresponding resistance characteristic values can accurately distinguish the gait cycle. Analysis on hysteresis and repeatability revealed that the sensor exhibits a constant electrical performance. Four kinds of motion postures were predicted and judged by comparing the resistance characteristic range value, peak value calculation function and time axis. The measured sensor outputs were transferred to a computer via 4.0 Bluetooth. Matlab language was used to detect the status through a rule-based algorithm and the sensor outputs.

Prevalence and quantification of contamination of knitted cotton outer gloves during hip and knee arthroplasty surgery.

INTRODUCTION: Knitted cotton outer gloves offer protection against surgical glove perforation and provide improved grip on instruments. These gloves absorb blood and other fluids during surgery, and may therefore also accumulate contaminating bacteria. To date, there is no published data on microbial contamination of such gloves during surgery. METHODS: Knitted cotton outer gloves used in primary and revision hip and knee arthroplasty from two Swiss hospitals were analysed by quantitative bacteriology. Samples were subjected to sonication and vortexing, followed by membrane filtration of the sonicate. Membranes were incubated under aerobic and anaerobic culture conditions, respectively, for 21 days. Total microbial load for each pair of gloves was determined by colony-forming units (CFU) count. Strain identification was performed with MALDI-TOF. RESULTS: A total of 43 pairs of gloves were collected from continuous series of surgeries. Under aerobic culture conditions, total CFU counts ranged 0-1103, 25 (58%) samples remaining sterile, and 4 (9%) yielding > 100 CFU. Under anaerobic culture conditions, total CFU counts ranged 0-3579, 22 (51%) samples remaining sterile, 6 (14%) yielding > 100 CFU. The only covariate significantly associated with the level of contamination was the provider hospital (p < 0.0001 for aerobic and p = 0.007 for anaerobic cultures). Strain identification revealed only skin commensals, mainly coagulase-negative staphylococci and Propionibacterium spp. CONCLUSION: While contamination of surgical latex gloves is a well-known issue, no study has examined so far contamination of knitted cotton outer gloves. No or very low microbial contamination could be identified in the majority of the knitted cotton outer gloves assayed. However, a relevant proportion showed contamination far higher than estimated minimal thresholds for implant-associated infection. Clinical relevance of these findings remains to be established.

Wearable Intrinsically Soft, Stretchable, Flexible Devices for Memories and Computing.

A recent trend in the development of high mass consumption electron devices is towards electronic textiles (e-textiles), smart wearable devices, smart clothes, and flexible or printable electronics. Intrinsically soft, stretchable, flexible, Wearable Memories and Computing devices (WMCs) bring us closer to sci-fi scenarios, where future electronic systems are totally integrated in our everyday outfits and help us in achieving a higher comfort level, interacting for us with other digital devices such as smartphones and domotics, or with analog devices, such as our brain/peripheral nervous system. WMC will enable each of us to contribute to open and big data systems as individual nodes, providing real-time information about physical and environmental parameters (including air pollution monitoring, sound and light pollution, chemical or radioactive fallout alert, network availability, and so on). Furthermore, WMC could be directly connected to human brain and enable extremely fast operation and unprecedented interface complexity, directly mapping the continuous states available to biological systems. This review focuses on recent advances in nanotechnology and materials science and pays particular attention to any result and promising technology to enable intrinsically soft, stretchable, flexible WMC.

A review of e-textiles in neurological rehabilitation: How close are we?

Textiles able to perform electronic functions are known as e-textiles, and are poised to revolutionise the manner in which rehabilitation and assistive technology is provided. With numerous reports in mainstream media of the possibilities and promise of e-textiles it is timely to review research work in this area related to neurological rehabilitation.This paper provides a review based on a systematic search conducted using EBSCO- Health, Scopus, AMED, PEDro and ProQuest databases, complemented by articles sourced from reference lists. Articles were included if the e-textile technology described had the potential for use in neurological rehabilitation and had been trialled on human participants. A total of 108 records were identified and screened, with 20 meeting the broad review inclusion criteria. Nineteen user trials of healthy people and one pilot study with stroke participants have been reported.The review identifies two areas of research focus; motion sensing, and the measurement of, or stimulation of, muscle activity. In terms of motion sensing, E-textiles appear able to reliably measure gross movement and whether an individual has achieved a predetermined movement pattern. However, the technology still remains somewhat cumbersome and lacking in resolution at present. The measurement of muscle activity and the provision of functional electrical stimulation via e-textiles is in the initial stages of development but shows potential for e-textile expansion into assistive technologies.The review identified a lack of high quality clinical evidence and, in some cases, a lack of practicality for clinical application. These issues may be overcome by engagement of clinicians in e-textile research and using their expertise to develop products that augment and enhance neurological rehabilitation practice.

Wearable Goniometer and Accelerometer Sensory Fusion for Knee Joint Angle Measurement in Daily Life.

Human motion analysis is crucial for a wide range of applications and disciplines. The development and validation of low cost and unobtrusive sensing systems for ambulatory motion detection is still an open issue. Inertial measurement systems and e-textile sensors are emerging as potential technologies for daily life situations. We developed and conducted a preliminary evaluation of an innovative sensing concept that combines e-textiles and tri-axial accelerometers for ambulatory human motion analysis. Our sensory fusion method is based on a Kalman filter technique and combines the outputs of textile electrogoniometers and accelerometers without making any assumptions regarding the initial accelerometer position and orientation. We used our technique to measure the flexion-extension angle of the knee in different motion tasks (monopodalic flexions and walking at different velocities). The estimation technique was benchmarked against a commercial measurement system based on inertial measurement units and performed reliably for all of the various tasks (mean and standard deviation of the root mean square error of 1:96 and 0:96, respectively). In addition, the method showed a notable improvement in angular estimation compared to the estimation derived by the textile goniometer and accelerometer considered separately. In future work, we will extend this method to more complex and multi-degree of freedom joints.

Modern Electromagnetic-Radiation-Shielding Materials Made Using Different Knitting Techniques.

This paper summarizes the possibility of employing knitted textile barriers as a shield against electromagnetic fields to protect the human body from their negative impact. Ten variants of knitted fabrics made of electrically conductive yarns, steel, and copper wire that differed in stitch pattern, structural parameters, and raw material, were designed, manufactured, and tested. The knitted fabrics produced differed in structural parameters, including course and wale density, surface density, thickness, thread length in the loop, wale and course take-up, volume cover factor, and surface porosity. These parameters were examined in accordance with the research methodology used in knitting. Barrier measurements were taken in the direction of the wales and in the direction of the courses for two frequencies of electromagnetic fields: 2-4 GHz and 4-7 GHz. It was observed that the shielding effectiveness of the manufactured materials depends on the structural parameters of the fabric, the stiches applied, and the type of yarn.

A nine-month repeat-dose intravaginal ring (Ovaprene) irritation study in sheep.

OBJECTIVES: Ovaprene is a novel, investigational, intravaginal hormone-free monthly ring contraceptive designed for use in women of reproductive age to be worn over multiple weeks (one menstrual cycle). The objective of this work was to evaluate the safety of Ovaprene during a nine-month repeat-dose sheep study. STUDY DESIGN: In addition to traditional safety endpoints such as histopathological evaluation of the sheep female reproductive tract, vaginal fluids were collected and tested for released iron over time. Also, the amount of iron in the rings was assessed following removal, and serum iron levels were measured. There were four sheep in each group (Ovaprene group and sham group). RESULTS: There were no macroscopic clinical findings. There was minimal to mild, mixed or mononuclear cell infiltration present in all levels of vagina (cranial, mid, and caudal) from all animals including sham controls based on post-study necropsy. The female reproductive tract from animals treated with the Ovaprene ring was comparable to the sham controls. The concentrations of serum iron in sheep treated with Ovaprene ring were similar compared to a sham treated animal. The average amount of ferrous gluconate released from Ovaprene over the 29-day period of use was 175 mg of the approximately 512 mg nominally loaded into the rings. CONCLUSIONS: Overall, the Ovaprene devices were well-tolerated in female sheep. IMPLICATIONS: This study should support a chronic (e.g., one year) contraceptive efficacy study in women.