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This report has been commissioned by the Swedish Environmental Protection Agency (Naturvårdsverket) with the aim to investigate the potential influence of yarn construction on the fragmentation of microplastic fibres (MPF) in textile fabrics. The analyses were conducted on multiple fabrics with identical constructions but utilizing different types of yarn, such as spun yarn and filament yarn. These fabrics underwent various test simulating the wear experienced throughout a fabric’s lifecycle, including washing, abrasion, and pilling. The research findings highlight the significant influence of yarn type on shedding behaviour. Specifically, spun yarn demonstrates a heightened propensity to shed fibre fragments compared to filament yarns, particularly noticeable during flat abrasion test such as pilling and Martindale, as well as during laundry processes. In contrast, regardless of being spun- or filament yarn, viscose yarn demonstrated lower fibre shedding rates compared to polyester yarn. Furthermore, the chemical recycled polyester yarn showed a tendency to shed more fibre fragments than primary polyester yarn. The conclusions drawn from this report underscores the importance of incorporating yarn quality considerations into eco-design requirements, as suggested by the EU Commission, to effectively mitigate environmental impacts. Further research is essential to enhance our understanding of the factors influencing fibre shedding and to develop efficient strategies for sustainable product design and regulation.

Background. The efect of transcutaneous electrical nerve stimulation (TENS) on pain and impression of change was assessed during a 2.5-hour intervention on the frst postoperative days following hip surgery in a randomized, single-blinded, placebo-controlled trial involving 30 patients. Methods. Mixed-frequency TENS (2 Hz/80 Hz) was administered using specially designed pants integrating modular textile electrodes to facilitate stimulation both at rest and during activity. The treatment outcome was assessed by self-reported pain Numerical Rating Scale (NRS) and Patient Global Impression of Change (PGIC) scores at four time points. The ability to perform a 3-meter walk test and the use of analgesics were also evaluated. Group comparison and repeated-measure analysis were carried out using nonparametric statistics. Results. The active TENS group exhibited signifcantly higher PGIC scores after 30 minutes, which persisted throughout the intervention (all p ≤ 0.001). A reduction in NRS appeared after one hour of active TENS, persisting throughout the intervention (all p ≤ 0.05). The median group diferences in pain ratings were greater than the minimum clinically important diference, and the analysis of pain trajectories confrmed clinical signifcance at the individual level. Moreover, patients in the active TENS group were more likely able to perform a 3-meter walk test by the end of the intervention (p = 0.04). Analysis of the opioid-sparing effect of TENS was inconclusive (p = 0.066). No postoperative surgical complications or TENS-related side efects were observed during the study. Conclusion. Mixed-frequency TENS integrated in pants could potentially be an interesting addition to the arsenal of treatments for multimodal analgesia following hip surgery. This trial is registered with NCT05678101.

Neuromuscular electrical stimulation (NMES) of the quadriceps (Q) may increase venous blood flow to reduce the risk of venous thromboembolism. This study assessed whether Q-NMES pants could increase peak venous velocity (PVV) in the femoral vein using Doppler ultrasound and minimize discomfort. On 15 healthy subjects, Q-NMES using textile electrodes integrated in pants was applied with increasing intensity (mA) until the first visible muscle contraction [measurement level (ML)-I] and with an additional increase of six NMES levels (ML II). Discomfort using a numeric rating scale (NRS, 0–10) and PVV were used to assess different NMES parameters: frequency (1, 36, 66 Hz), ramp-up/-down time (RUD) (0, 1 s), plateau time (1.5, 4, and 6 s), and on:off duty cycle (1:1, 1:2, 1:3, 1:4). Q-NMES pants significantly increased PVV from baseline with 93% at ML I and 173% at ML II. Frequencies 36 Hz and 66 Hz and no RUD resulted in significantly higher PVV at both MLs compared to 1 Hz and 1 s RUD, respectively. Plateau time, and duty cycle did not significantly change PVV. Discomfort was only significantly higher with increasing intensity and frequency. Q-NMES pants produces intensity- dependent 2−3-fold increases of venous blood flow with minimal discomfort. The superior NMES parameters were a fre- quency of 36 Hz, 0 s RUD, and intensity at ML II. Textile-based NMES wearables are promising for non-episodic venous thromboembolism prevention.

Electronic textiles (E-textiles) are made using various materials including carbon nanotubes, graphene, and graphene oxide. Among the materials here, e-textiles are fabricated with reduced graphene oxide (rGO) coating on commercial textiles. rGO-based yarns are prepared for e-textiles by a simple dip coating method with subsequent non-toxic reduction. To enhance the conductivity, the rGO yarns are coated with poly(3,4-ethylene dioxythiophene): poly(styrenesulfonic acid) (PEDOT) followed by electrochemical polymerization of polypyrrole (PPy) as the electromechanically active layer, resulting in textile actuators. The rGO-based yarn actuators are characterized in terms of both isotonic displacement and isometric developed forces, as well as electron microscopy and resistance measurements. Furthermore, it is demonstrated that both viscose rotor spun (VR) and viscose multifilament (VM) yarns can be used for yarn actuators. The resulting VM-based yarn actuators exhibit high strain (0.58%) in NaDBS electrolytes. These conducting yarns can also be integrated into textiles and fabrics of various forms to create smart e-textiles and wearable devices.

Smart textiles combine the features of conventional textiles with promising properties of smart materials such as electromechanically active polymers, resulting in textile actuators. Textile actuators comprise of individual yarn actuators, so understanding their electro-chemo-mechanical behavior is of great importance. Herein, this study investigates the effect of inherent structural and mechanical properties of commercial yarns, that form the core of the yarn actuators, on the linear actuation of the conducting-polymer-based yarn actuators. Commercial yarns were coated with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) to make them conductive. Then polypyrrole (PPy) that provides the electromechanical actuation is electropolymerized on the yarn surface under controlled conditions. The linear actuation of the yarn actuators is investigated in aqueous electrolyte under isotonic and isometric conditions. The yarn actuators generated an isotonic strain up to 0.99% and isometric force of 95 mN. The isometric strain achieved in this work is more than tenfold and threefold greater than the previously reported yarn actuators. The isometric actuation force shows an increase of nearly 11-fold over our previous results. Finally, a qualitative mechanical model is introduced to describe the actuation behavior of yarn actuators. The strain and force created by the yarn actuators make them promising candidates for wearable actuator technologies., Funding Agencies|Erling-Persson Family foundation; Promobilia Foundation [A21024, A22122, A21029, 825232]; European Union [2009~00971]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU); [F17603]

Purpose: To compare fixed transverse textile electrodes (TTE) knitted into a sock versus motor point placed standard gel electrodes (MPE) on peak venous velocity (PVV) and discomfort, during calf neuromuscular electrical stimulation (calf-NMES). Methods: Ten healthy participants received calf-NMES with increasing intensity until plantar flexion (measurement level I = ML I), and an additional mean 4 mA intensity (ML II), utilizing TTE and MPE. PVV was measured with Doppler ultrasound in the popliteal and femoral veins at baseline, ML I and II. Discomfort was assessed with a numerical rating scale (NRS, 0–10). Significance was set to p < 0.05. Results: TTE and MPE both induced significant increases in PVV from baseline to ML I and significantly higher increases to ML II, in both the popliteal and femoral veins (all p < 0.001). The popliteal increases of PVV from baseline to both ML I and II were significantly higher with TTE versus MPE (p < 0.05). The femoral increases of PVV from baseline to both ML I and II were not significantly different between TTE and MPE. TTE versus MPE resulted at ML I in higher mA and NRS (p < 0.001), and at ML II in higher mA (p = 0.005) while NRS was not significantly different. Conclusion: TTE integrated in a sock produces intensity-dependent increases of popliteal and femoral hemodynamics comparable to MPE, but results in more discomfort at plantar flexion due to higher current required. TTE exhibits in the popliteal vein higher increases of PVV compared to MPE. Trial registration: Trial_ID: ISRCTN49260430. Date: 11/01/2022. Retrospectively registered.

Purpose Physical inactivity is associated with muscle atrophy and venous thromboembolism, which may be prevented by neuromuscular electrical stimulation (NMES). This study aimed to investigate the effect on discomfort, current amplitude and energy consumption when varying the frequency and phase duration of low-intensity NMES (LI-NMES) via a sock with knitting-integrated transverse textile electrodes (TTE). Methods On eleven healthy participants (four females), calf-NMES via a TTE sock was applied with increasing intensity (mA) until ankle-plantar flexion at which point outcomes were compared when testing frequencies 1, 3, 10 and 36 Hz and phase durations 75, 150, 200, 300 and 400 µs. Discomfort was assessed with a numerical rating scale (NRS, 0–10) and energy consumption was calculated and expressed in milli-Joule (mJ). Significance set to p ≤ 0.05. Results 1 Hz yielded a median (inter-quartile range) NRS of 2.4 (1.0–3.4), significantly lower than both 3 Hz with NRS 2.8 (1.8–4.2), and 10 Hz with NRS 3.4 (1.4–5.4) (both p ≤ .014). Each increase in tested frequency resulted in significantly higher energy consumption, e.g. 0.6 mJ (0.5–0.8) for 1 Hz vs 14.9 mJ (12.3–21.2) for 36 Hz (p = .003). Longer phase durations had no significant effect on discomfort despite generally requiring significantly lower current amplitudes. Phase durations 150, 200 and 400 µs required significantly lower energy consumption compared to 75 µs (all p ≤ .037). Conclusion LI-NMES applied via a TTE sock produces a relevant plantar flexion of the ankle with the best comfort and lowest energy consumption using 1 Hz and phase durations 150, 200 or 400 µs.

Recently, electrically driven conducting polymer (CP) coated yarns have shown great promise to develop soft wearable applications because of their electrical and mechanical behaviour. However, designing a suitable yarn actuator for textile-based wearables with high strain is challenging. One reason for the low strain is the voltage drop along the yarn, which results in only a part of the yarn being active. To understand the voltage drop mechanism and overcome this issue intrinsically conductive yarns were used to create a highly conductive path along the full length of the yarn actuator. Ag plated knit-de-knit (Ag-KDK) structured polyamide yarns were used as the intrinsically conductive core material of the CP yarn actuators and compared with CP yarn actuators made of a non-conductive core knit-de-knit (KDK) yarn. The CP yarn actuators were fabricated by coating the core yarns with poly(3,4-ethylene dioxythiophene): poly(styrene sulfonic acid) followed by electrochemical polymerization of polypyrrole. Furthermore, to elucidate the effect of the capillarity of the electrolyte through the yarn actuator, two different approaches to electrochemical actuation were applied. All actuating performance of the materials were investigated and quantified in terms of both isotonic displacement and isometric developed forces. The resultant electroactive yarn exhibits high strain (0.64 %) in NaDBS electrolytes as compared to previous CP yarn actuator. The actuation and the electroactivity of the yarn were retained up to 100 cycles. The new highly conductive yarns will shed light on the development of next-generation textile-based exoskeleton suits, assistive devices, wearables, and haptics garments.

With the rise of ion-based devices using soft ionic conductors, ionotronics show the importance of matching electronic and biological interfaces. Since textiles are conformal, an essential property for matching interfaces, light-weight and comfortable, they present as an ideal candidate for a new generation of ionotronics, i-textiles. As fibers are the building blocks of textiles, ionically conductive fibers, named ionofibers, are needed. However, ionofibers are not yet demonstrated to fulfill the fabric manufacturing requirements such as mechanical robustness and upscaled production. Considering that ionogels are known to be conformal films with high ionic conductivity, ionofibers are produced from commercial core yarns with specifically designed ionogel precursor solution via a continuous dip-coating process. These ionofibers are to be regarded as composites, which keep the morphology and improve the mechanical properties from the core yarns while adding the (ionic) conductive function. They keep their conductivity also after their integration into conformal fabrics; thus, an upscaled production is a likely outlook. The findings offer promising perspectives for i-textiles with enhanced textile properties and in-air electrochemical applications., WEAFING

Smart textile yarns have already shown their potential for fabrication of textile actuators. However, their actuation strain and force have been limited so far. Accordingly, twisting, and coiling techniques have attracted much attention to enhance the strain and force of yarn actuators. In this regard, coiled yarns that actuate under a liquid electrolyte have been studied well, but coiled yarn actuators that work in air are not explored as much. In this work, a double coiled yarn structure that works in air is designed, prepared, and investigated. Commercial textile yarns were coated with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution. Thereafter, yarns were coiled using a motorized stage. Two coiled yarns, as cathode and anode, are then placed near each other and covered with an ionogel precursor mixture containing an ionic liquid as ion reservoir. The gel is cured and set using UV emission. The actuation properties of the prepared double coiled yarn actuator were investigated in air. A square wave potential of ±2 V was applied, and strain response of the actuator yarns was measured. The results showed that prepared double coiled yarn can potentially be a promising candidate as soft actuators in wearables and garments, e.g. for haptic applications.

The development of actuating wearable textiles is of great interest in fields as 30haptics or assistive devices. Electroactive conducting polymer-based actuatorsare being merged with yarns and fabrics to provide them with mechanicalactuation. One way to speed up the development of such mechanically activewearable textiles is the development of conducting polymer-based actuators thatcan be incorporated into textile processing. This imposes extra requirements tothe actuators such as the required size, improved mechanical andelectrochemical stability, actuation in air or the use of low/non-hazardousmaterials. Tape yarn actuators composed of conducting polymer/ionicallyconducting layer/conducting polymer are being developed and optimized to thataim. The latest developments on integrating such EAP tape yarns in wovenfabrics will be presented.

Commercially available yarns are promising precursor for artificial muscles for smart fabric-based textile wearables. Electrochemically driven conductive polymer (CP) coated yarns have already shown their potential to be used in smart fabrics. Unfortunately, the practical application of these yarns is still hindered due to their slow ion exchange properties and low strain. Here, a method is demonstrated to morph poly-3,4-ethylenedioxythiophene:poly-styrenesulfonate (PEDOT:PSS) coated multifilament textile yarns in highly twisted and coiled structures, providing >1% linear actuation in <1 s at a potential of +0.6 V. A potential window of +0.6 V and -1.2 V triggers the fully reversible actuation of a coiled yarn providing >1.62% strain. Compared to the untwisted, regular yarns, the twisted and coiled yarns produce >9x and >20x higher strain, respectively. The strain and speed are significantly higher than the maximum reported results from other electrochemically operated CP yarns. The yarns actuation is explained by reversible oxidation/reduction reactions occurring at CPs. However, the helical opening/closing of the twisted or coiled yarns due to the torsional yarn untwisting/retwisting assists the rapid and large linear actuation. These PEDOT:PSS coated yarn actuators are of great interest to drive smart textile exoskeletons., Funding Agencies|Promobilia Foundation [F17603]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009-00971]; Swedish Research CouncilSwedish Research Council [2014-3079]; Carl Trygger Foundation [CTS:17-215]; European UnionEuropean Union (EU) [825232]; University of Wollongongs Visiting International Scholar Award

Textile electrodes, also called textrodes, for biosignal monitoring as well as electrostimulation are central for the emerging research field of smart textiles. However, so far, only the general suitability of textrodes for those areas was investigated, while the influencing parameters on the contact impedance related to the electrode construction and external factors remain rather un-known. Therefore, in this work, six different knitted electrodes, applied both wet and dry, were compared regarding the influence of specific knitting construction parameters on the three-electrode contact impedance measured on a human forearm. Additionally, the influence of applying pressure was investigated in a two-electrode setup using a water-based agar dummy. Further, simulation of an equivalent circuit was used for quantitative evaluation. Indications were found that the preferred electrode construction to achieve the lowest contact impedance includes a square shaped electrode, knitted with a high yarn density and, in the case of dry electrodes, an uneven surface topography consisting of loops, while in wet condition a smooth surface is favorable. Wet electrodes are showing a greatly reduced contact impedance and are therefore to be preferred over dry ones; however, opportunities are seen for improving the electrode performance of dry electrodes by applying pressure to the system, thereby avoiding disadvantages of wet electrodes with fluid administration, drying-out of the electrolyte, and discomfort arising from a “wet feeling”. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Commercial yarns can be functionalized with conducting polymers (CPs) todevelop yarn and textile actuators. Here we show a method of functionalizationof commercial polyamide yarns by poly-3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) coating. Aftercoating, while PEDOT:PSS is drying, it is possible to twist and coil the yarns,resulting in a major improvement of their linear strain and speed of movement.By using a potential window between +0.6 V and -1.2 V vs Ag/AgCl it waspossible to obtain a fully reversible actuation of a coiled yarn providing up to1.62% strain. A strain higher than 1% was achieved in less than 1 second.Compared to the untwisted, regular yarns, the twisted and coiled yarns produce>9× and >20× higher strain, respectively. These results are a step forward towardsthe development of soft, silent and compliant smart textile exoskeletons.

Ions are prevalent within bioelectronics, as they are the main charge carriers in living systems. In contrast to electronic systems, ionic ones are closer to what can be found in our body; in muscles, neurons and nerves. Textiles are a much-used biomedical material, both in vivo and in vitro due to its membrane character, highly efficient area, softness, biocompatibility and biodegradability. Modifying the physicochemical properties of the core or the surface of textile has been reported a countless number of times, but still, its use in a bioelectrical context is limited. Fibres are the building blocks of textiles and what make textiles an architected class of material. Then ionically conductive fibres are of great interest. Here, we show the preparation of iono-conductive textile fibres through the (semi-)continuous dip-coating of ionogel on the cellulose-based viscose. Ionogels are composed of salts in liquid state and a 3-dimensional solid network, in our case an ionic liquid (IL), 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, commonly named EMIm OTf or EMIm Triflate, and a thiol acrylate network, allowing the mobility of the ions within or in/out of the gel. This specific combination is a first effort towards the development of ionic textile fibres and ionic smart textiles, as a variety of ILs with different cations and anions exists, potentially allowing a large number of different combinations. We investigate how the coating of this ionogel affects the mechanical properties as well as the conductivity in AC or DC arrangement and their relation to temperature and humidity. Also, the thermal stability and sensitivity of degradation of the fibre system is studied. Moreover, we introduce different textile structures, and potential applications directed to bioelectronics.

Nonconductive commercial viscose yarns have been coated with a commercial conducting poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) layer providing electrical conductivity which allowed a second coating of the electroactive conducting polymer polypyrrole through electropolymerization to develop textile yarns actuators. To simplify the PEDOT coating process and at the same time make this process more suitable for application in industry, a new coating method is developed and the properties of the PEDOT-PSS conducting layer is optimized, paying attention on its effect on the actuation performance. The effect of the concentration of an additive such as dimethylsulfoxide (DMSO) on actuation, and of PEDOT:PSS layers, is investigated. Results show that on improving this conducting layer, better performance than previously developed yarn-actuators is obtained, with strains up to 0.6%. This study provides a simple and efficient fabrication method toward soft, textile-based actuators for wearables and assistive devices with improved features., Funding agencies: The authors acknowledge the Erling-Persson Family Foundation,Promobilia Foundation (F17603), Union’s Horizon 2020 research andinnovation program under grant agreement no. 825232 “WEAFING”for their nancial support. E.W.H.J. acknowledges nancial support fromthe Swedish Government Strategic Research Area in Materials Science onFunctional Materials at Linköping University (Faculty Grant SFO Mat LiUNo. 2009 00971). F.E-T. acknowledges Universidad Tecnica de Ambato(UTA-FCIAL-UODIDE-2018-0047-M) for the financial support.