Electronic textiles

Resume : As the lines between computing and textiles blur, so do the lines between computing and our bodies. Wearable technology is evolving to a point where it pervades many aspects of our lives, and we have become accustomed to being surrounded with technological conveniences. Soon, our garments will become mobile devices that will seamlessly connect us to our networks, give and receive vital information through interfaces that become so integrated into our actions and activities that they become less invasive but more pervasive. Here we look at the application of electronic circuits and sensors onto textile in the creation of garment based wearables. These products have been engineered to feel and perform like a regular textile: they have drape, flexibility, are comfortable and durable. Once woven, sewn or printed into a garment or accessory, the general consumer can respond with much greater ease than with a traditional electronic device. Case studies will demonstrate the discovery and application of various methods of embedding circuits to textiles for wearable technology projects. The benefits of bringing technology ?out of the box? will revolutionize how we approach many aspects of our current lives.

Resume : The vision of 1D-NEON is to develop fibre-based smart materials and integrated technology platforms for the manufacturing in Europe of high value-added smart textiles, with applications in Large-Area electronics, Energy, Sensing and Soft robotics. 1D-NEON builds on a modular platform where nanomaterials are assembled into five basic fibre components along with textile-based manufacturing processes for integration of e-fibre components into smart products. The project brings together 14 partners from 7 European countries active in advanced materials, design platforms, textiles, electronics and photonic sectors. The talk will review the main challenges of currently available state-of-the art technologies and discuss opportunities to bring innovation into key market sectors of e-textiles, with the help of selected new product examples and lessons learned, both from the 1D-NEON partners and others.

Resume : Stretchable energy storage microsystems composed of thin-film supercapacitors and Li-ion microbatteries (µLIBs) have attracted attention to meet the requirements of autonomous wearable technologies such as shape-conformable portable wireless gadgets or smart textiles. With many advantages such as high surface area and improved charge transport, self-supported 3-D nanostructured metal oxides such as titania nanotubes (TiO2nts) are promising electrode materials for µLIBs [1-3]. This talk will review the concept and fabrication of all-solid-state µLIBs using TiO2nts as negative electrode. Fundamentals such as electrode reactions, lithium ion diffusion and the conformal electrodeposition mechanism of polymer electrolytes into nanostructured electrodes will be presented. The fabrication of a full 3D microcell showing high electrochemical performance will be shown and the development of the next generation of flexible and stretchable 3D microbatteries for electronic textiles will be discussed. References [1] B.L. Ellis, P. Knauth, T. Djenizian, Adv. Mater., 26 (2014) 3368. [2] N. Plylahan, M. Letiche, M. Barr, B. Ellis, S. Maria, T. N. T. Phan, E. Bloch, P. Knauth, and T. Djenizian, J. Power Sources, 273, 1182 (2015). [3] G. Salian, C. Lebouin, A. Demoulin, P. Knauth, M. Lepikhin, A. Galeyeva, A. Kurbatov, and T. Djenizian, J. Power Sources, 340, 242 (2017).

Resume : Wearable electronics is a growing field of research and a quite large number of devices that are suitable for and would benefit from a direct integration in/onto clothing have been introduced. However, all of these devices need some form of electrical power. Due to weight increasing with capacity, batteries are not a good solution for wearable electronics. Therefore, different methods of energy harvesting have been proposed. Here mainly the wearer is targeted as a source of energy (e.g. kinetic energy from movement and thermal energy from body heat). However, most of these sources bring only very limited amounts of available charge. When a textile could be based on a photovoltaic fabric, enough energy for most electronic gadgets could be generated. In this paper we show a proof of principle device of an organic solar cell built on a single viscose fiber. The concept and the preparation of the device will be shown. All components of the presented photovoltaic device were applied using methods suitable for up-scaling to a roll-to-roll process. Finally, the electrical characteristics of such a device will be shown and discussed with respect to other organic photovoltaic devices.

Resume : Wearable power supplies are a critical component in any wearable electronic system. Here we present a textile that generates electrical power from a ubiquitous source of “waste” energy; our body movements. We demonstrate how piezoelectric yarns can be fabricated through melt-spinning of PVDF into fibres with a core/sheath configuration. The core is a composite of 10% carbon black in polyethylene, and serves as the inner electrode. Electrically conducting yarns were used as the outer electrode, as this is the most suitable for practical applications. Melt spinning was carried out in a pilot scale spinning line at 800 m/min. We have fabricated woven straps where the piezoelectric yarn is combined with a variety of electrically conducting yarns. During cyclic stretching in a tensile tester, the straps repeatedly generate an output of several volts at a strain of 0.25%. The measured electronic output, which depends on the weave pattern and the properties of the conducting yarn, can be relevantly described with an LTspice-model. Its functionality is demonstrated by using our textile as the shoulder strap attached to a laptop case, which permits to scavenge energy during walking using a standard energy harvesting circuit.

Resume : Generating and harvesting energy offer new possibilities to smart materials such as textiles. The alliance of textile and electric technologies is necessary to develop piezoelectric fabrics: Indeed flexibility and energy creation are required for such components. To achieve the desired characteristics, PVDF piezoelectric fibres can be produced by melt spinning, because this polymer is able to have piezoelectric properties when crystallizing under a β-phase. Optimizing the content of β-phase is then a key challenge to developing such fibres. The transformation of non-polar α-phase to polar β-phase can be controlled by adjusting drawing ratio and processing temperatures. Firstly, the β phase content is optimized in PVDF, then the material is poling by contact to accentuate piezoelectric character by reorienting the macroscopic dipoles. Dynamic Mechanical Analysis (DMA) tests coupled to a Keithley voltmeter allow the solicitation of PVDF woven samples. A variation of voltage is obtained in compression. The second part involves the development of a tricomponent fibre. Two layers of conductive polymers acting as external/internal electrodes are placed on either side of the PVDF layer. Obtaining excellent interfacial adhesion between each layer is crucial for increasing the sensitivity of the electrodes. A new conductive property has been added to the piezoelectricity of the fibre in order to create a textile that can be used as a mechanical sensor and energy harvesting application.

Resume : Thermoelectric (TE) materials can be used to convert heat to electric energy and there is a significant interest in producing flexible and efficient TE generator solutions for wearable devices and sensors.[1] In particular, a flexible TE generator integrated with light-weight and comfortable textile substrates could be an enabling platform for body-heat-based energy harvesting.[2] Atomic layer deposition (ALD) is a highly controllable technique to deposit semiconducting inorganic materials directly on both yarns and textiles.[3] Combining ALD with molecular layer deposition (MLD) enables the fabrication of hybrid inorganic-organic materials with increased flexibility. We have deposited pristine zinc oxide (ZnO) and ZnO–organic superlattice thin films on a cotton textile using ALD/MLD.[4] The TE properties of our ZnO and ZnO–organic superlattice coatings are comparable to those for thin films deposited on conventional inorganic substrates. The ZnO–organic superlattice thin films moreover show enhanced resistance to mechanical strain, providing an exciting materials platform for further research towards TE/textile integration. [1] Z. L. Wang, W. Wu, Angew. Chem. Int. Ed. 2012, 51, 11700. [2] J. Bahk, H. Fang, K. Yazawa, A. Shakouri, J. Mater. Chem. C. 2015, 3, 10362. [3] G. N. Parsons, in ALD of Nanostructured Materials (Eds: N. Pinna, M. Knez), Wiley-VCH, 2012, p. 271. [4] A. J. Karttunen, L. Sarnes, R. Townsend, J. Mikkonen, M. Karppinen, Adv. Electron. Mater. 2017, in press.

Resume : Recent developments in technologies for small wearable electronic devices, such as wearable health and fitness monitors, has led to an increased demand for energy storage devices that are capable of meeting the power demands of these new devices while simultaneously being incorporated into the wearable device [1]. Herein, we report on polymer-MXene composites as potential building blocks for producing fibers and textiles that are capable of storing and delivering energy. MXenes are a large family of 2D transition metal carbides and nitrides, which show great promise for energy storage applications due to their high conductivity and intrinsic pseudocapacitive properties [2]. The MXene-polymer composites are promising candidates for flexible, ultrahigh-rate supercapacitor electrodes. These composites maximize the exposed surface area of the MXene materials which increases the accessibility of the electrolyte to the active material, as well as optimizing electrolyte diffusion during charging and discharging. Additionally, the production of hollow MXene fibers with increased transparency is possible. The versatility of MXene-polymer composite fibers sets them apart from other composite materials for the fabrication of multifunctional wearable electronic devices. References: 1. K. A. Jost, G. Dion, Y. Gogotsi, Textile Energy Storage in Perspective, J. Mater. Chem. A, 2 (28), 10776 - 10787 (2014) 2. B. Anasori, M. R. Lukatskaya, Y. Gogotsi, 2D metal carbides and nitrides (MXenes) for energy storage, Nature Reviews Materials, 2, 16098 (2017)

Resume : We have developed new electronic textile fabrication techniques with reel to reel micro machining and weaving integration in order to realize meter-scale large area devices for wearable and automotive applications. Conventional MEMS technologies utilizing the microfabrication equipment based on semiconductor manufacturing process, however, may not be suitable for large area MEMS devices manufacturing, because vacuum process equipment for large-area devices is too expensive, and large-area substrates are difficult to be handled and too costly. Our proposed process can offer large area devices with low cost machining tools because nano/micro film deposition and patterning area for fiber is small and automatic weaving of meter-wide textile is commonly available. In addition to the weaving, we also integrated MEMS sensors on textiles by low temperature chip mounting techniques. The developed continuous processing of fiber is composed of die-coating to form organic functional materials including P3HT, PVDF, PEDOT:PSS, PMMA, 3-D photolithography to pattern MEMS structure, chip mounting to integrate silicon devices on fibers. On our die coating system, fiber-type substrates are moved continuously with supplier and winder, and are coated by solution with the coating tool called “die”. Hundreds of nanometer thick functional films for semiconductor devices are formed by our analysis and design of die and by pressure control of the solution. Our 3-D photolithography technology for a high resolution micro process on a fiber mainly comprises the 3-D exposure module and spray deposition of thin resist film on the fiber. 3-D exposure module with long service life, low cost, narrow print gap and thus high resolution is fabricated by the wet etching of a quartz substrate and the projection exposure method. Thin 1 um thick resist is sprayed on the fiber substrates by tuning viscosity and volatility of the resist systematically. The low temperature chip mounting system for fiber and textile consists of chip mounter, dispensers and heaters. The LEDs and MEMS force sensors have been mounted on the fiber substrate and texiles. The developed automatic weaving machine can weave resultant functional fibers by defining the position of the functional fibers precisely with a linear actuator and an alignment camera. The weaving machine is 1.2 m wide and has two rapiers to weave not only polyester fibers but also functional fibers. Since cross-shaped alignment marks are patterned on the functional fiber substrates, the rapier of functional fibers grasps and moves the fiber for detecting the alignment mark for fixing the position of the fiber. Then, it weave the functional fibers between the open spaces between the warps. The large electronic textile including LED array fabric, MEMES sensor fabric, touch sensors, and solar cells is woven continuously with our looming machine, which leads to the applications including wearable and automotive applications.

Resume : The grafting of poly(hydroxyethylmethacrylate) on conventional track etched polyester membranes via ATRP[1] and subsequent modification with a light responsive spiropyran derivative is described. This method leads to photo-responsive membranes or textiles with desirable properties such as light-responsive permeability changes.[2] The controlled polymerization procedure allows good control over the thickness of the polymer layer in respect to the polymerization conditions. Therefore, the final permeability of the membranes could be tailored by choice of pore diameter of the initial membranes, applied monomer concentration or polymerization time. Moreover a remarkable switch in permeability of caffeine (more than 1000%) upon irradiation with UV light could be achieved. We could produce membranes with either an on-off effect, or with two different, finite caffeine permeability values. These properties enable possible applications in the field of transdermal drug delivery, filtration, or sensing. [1] F. Teixeira Jr., A. M. Popa, S. Guimond, D. Hegemann, R. M. Rossi, J. Appl. Polym. Sci. 2013, 129, 636 – 643. [2] L. Baumann, K. Scholler, D. de Courten, D. Marti, M. Frenz, M. Wolf, R. M. Rossi, L. J. Scherer, RSC Advances 2013, 3 , 23317-23326.

Resume : Recently, E-textile, an electronic device embedded in clothing or garment has attracted attention because of its various application such as motion controller, health-care device, gesture monitoring, and wireless communication. In order to develop an advanced E-textile, which possesses utility of both clothing and electronic device, the development of conductive fiber is basically necessary. So far, most previous reports for the conductive fibers have mainly focused on high performance in both electrical property and mechanical property. However, when the conductive fiber is practically applied to E-textile, the performance of conductive fiber and E-textile would get worse by water such as sweat of user, rainwater, and humid weather. In addition, E-textile could break down when doing laundry for keeping E-textile clean. To overcome these limitations, development of conductive fiber with waterproof feature is required. In this research, we present a waterproof conductive fiber with facile fabrication process. The waterproof conductive fiber is fabricated from composite of flexible polymers and metal nanoparticles. Then, the surface of conductive fiber is treated with superhydrophbobic fluorocarbon agent through Self Assembled Monolayer technique. This waterproof conductive fiber exhibits outstanding electrical conductivity (resistance lower than 1Ω/cm), mechanical durability (slight resistance change despite 10000 times of folding deformation) also, it does not get wet or electrically degrade by water or sweat because of waterproof surface feature of conductive fiber. Furthermore, the conductive fiber showed a stable response in harsh and watery conditions such as acid rain, laundry. With the aforementioned results, the waterproof conductive fiber will provide electrical conductivity, mechanical durability, and watery-stability for operation condition of E-textile for more variable applications.

Resume : Functional electronic textiles have been largely made using conducting polymer coatings. Poly(3,4-ethylenedioxythiophene) (PEDOT) stabilized by polystyrene sulfonate (PSS)is a commercially available conductive formulation. Thanks to its soft nature, conducting properties, low redox potential and ease of processability, it offers outstanding performance in the field of bioelectronics. To avoid the PEDOT:PSS’s redispersion or post-process delamination, different chemicals are used with at the expense of a decrease in its conductivity. Here we present the introduction of the divinylsulfone (DVS) low temperature crosslinker in PEDOT:PSS formulation to improve its stability in humid conditions. We demonstrate that the crosslinking reaction can be performed at room temperature thanks to the high reactiveness of DVS vinyl groups. DVS does not affect the electronic conductivity of PEDOT:PSS, reaching values of 700 S/cm. PEDOT:PSS:DVS dispersion can be easily applied to textiles and used as electrodes with low surface resistivity and great biocompatibility. We also evaluate such electrodes during electromyography and electrocardiography recordings in dry and wet conditions. This new material shows great potential to make wearable and humidity stable devices in healthcare applications.

Resume : The field of advanced functional fibers and textiles is experiencing an unprecedented development owing for a large part to recent scientific and technological breakthroughs in fiber processing. The thermal drawing process in particular, the technique used to fabricate telecommunication optical fibers, now allows for the fabrication of fibers with a large range of materials and functionalities. Flexible polymer fibers have been demonstrated to integrate metallic electrode arrays, electrically addressed semiconducting and piezoelectric domains, micro-channels, or textured surfaces with nanometer feature sizes. This provides fibers with advanced optical but also electronic and optoelectronic functionalities, with intriguing opportunities in energy harvesting and storage, fiber probes, sensing, bioengineering and advanced textiles. In this presentation, we would like to introduce the vibrant field of multi-material fibers and highlight the several opportunities for the electronic fibers and textiles community. We will in particular present the fabrication approach, materials and achievable architectures offered by this process. We will then discuss a series of recent results to highlight these opportunities: textured fibers and micro-channels for bioengineering applications (Adv. Funct. Materials, in Press), electronic fibers for touch sensing (J. of Phys. D, accepted), and highly efficient photo-detecting and temperature sensing fibers.

Resume : Mechanical robustness, electrical and chemical reliabilities of devices against large deformations such as bending and stretching have become the key metrics for rapidly emerging wearable electronics. Metallic glasses (MGs) have high elastic limit, electrical conductivity, and corrosion resistance, which can be promising for applications in wearable electronics. However, their applications in wearable electronics or transparent electrodes have not been extensively explored so far. Here, we demonstrate stretchable and transparent electrodes using CuZr MGs in the form of nanotrough networks. MG nanotroughs are prepared by electrospinning and co-sputtering process, and they can be transferred to various desired substrates, including stretchable elastomeric substrates. The resulting MG nanotrough network is first utilized as a stretchable transparent electrode, presenting outstanding optoelectronic (sheet resistance of 3.8 Ω/sq at transmittance of 90%) and mechanical robustness (resistance change less than 30% up to a tensile strain of 70%) as well as excellent chemical stability against hot and humid environments (negligible degradation in performance for 240 h in 85% relative humidity and 85 °C). A stretchable and transparent heater based on the MG nanotrough network is also demonstrated with a wide operating temperature range (up to 180 °C) and excellent stretchability (up to 70% in the strain). The excellent mechanical robustness of these stretchable transparent electrode and heater is ascribed to the structural configuration (i.e., a nanotrough network) and inherent high elastic limit of MGs, as supported by experimental results and numerical analysis. We demonstrate their real-time operations on human skin as a wearable, transparent thermotherapy patch controlled wirelessly using a smartphone as well as a transparent defroster for an automobile side view mirrors, suggesting a promising strategy toward next-generation wearable electronics or automobile applications.

Resume : Today, wearable electronic devices combine a large variety of functional, stretchable and flexible technologies. Therefore, textiles are commonly considered to be the best substrates to accommodate electronic devices in a wearable use. Initially, commercially available solutions are exiting using metallic or carbon-based materials providing electrical functionality to the textiles. However, in many cases, such textiles fail under everyday usage conditions. In this work, we present the way of π-conjugated electroactive materials synthesis directly on textiles. This easy to apply and scalable technique enables the fabrication of highly conducting organic fabrics for an application in wearable electronic devices.

Resume : Smart textiles is an emergent, highly cross-disciplinary field most often defined in terms of the concept of interaction – a class of artefacts having textile as a vital part with the parable being a black box taking input from its surrounding and giving output to the same. In spite of this two-way-ness most focus within the smart textiles community has been devoted to the former – creating devices for measuring and monitoring physiological signals and alike. Here we discuss the next generation of smart textiles giving output, not only taking in-going stimulus. Specifically, we report on mechanical output such as form change, strain and stress amplification. Mechanical, as compared with mere electrical, output is highly anticipated as then textiles are able to mimic movements of organs as well as of machines. As textile is the material class that perhaps is most close to man taking part in whatever human activities highly interesting opportunities open up. We discuss some different textile cases; the TATA system, thermally activated textile actuators, which are two-way, reversible all-polymer systems; and recent results on textile actuators, textutators, based on electroactive polymers. We show that all could be up-scaled and taken to industrial level production. We therefore argue that textiles are complementing other large-area, flexible electronics technologies such as printed paper electronics. For the textuators it is found that by textile processing the a) stress and b) strain from simple actuating elements could be amplified and tuned. By parallel arrangements, the exerting force is increased linearly and by serial arrangement an order-of-magnitude strain increase is achieved. By this we show the great potential of second generation smart textiles for assistive devices, fluidics, active ventilation, cilia, soft robotics, exoskeletons and artificial muscles.

Resume : The main areas of liquid crystal (LCs) application are electro-optical displays, temperature sensors, smart windows, reflective pigments, and high modulus polymer fibers. Recently, there has been some work done on using LCs as sensors for nerve agents and toluene vapours. [1-2] Our group has developed coaxial electrospinning as an adaptable technique to obtain fiber mats consisting of LCs as core materials and a polymer as sheath. [3-5] These fiber mats are being developed as tensile and gas sensors [6], respectively, as a new type of wearable technology. Here, we present results on non-woven mats comprising of poly(vinylpyrrolidone) (PVP) sheath surrounding a core of nematic 4-cyano-4ʹpentylbiphenyl (5CB) liquid crystal. These fiber mats can function as non-electronic sensors to detect organic vapors at room temperature and its response to various VOC’s will be discussed. [6] Additionally, we will present electrospinning as a method to get core-sheath fibers with a liquid crystal elastomers (LCE) core. The core material during spinning is a liquid crystal monomer, cross-linker, photoinitiator and solvent, and the polymerization/cross-linking is done after fiber formation. The role of spinning parameters and environment on fiber morphology and thus obtained fiber mats are studied with respect to morphological, optical and mechanical response with various techniques. References: [1] Bedolla Pantoja M. A.; Abbott N. L., ACS Applied Materials & Interfaces 2016, 8, 13114-13122. [2] Rebecca J. Carlton R. J.; Hunter J. T.; Miller Daniel S.; Abbasi Reza; Mushenheim Peter C.; Tan Lie Na; and Abbott N. L. Liquid Crystals Reviews, 2013, 1, 18-21. [3] Lagerwall, J. P. F.; McCann, J. T.; Formo, E.; Scalia, G.; Xia, Y. Chem. Commun. 2008, 42, 5420-5422. [4] Enz, E.; Lagerwall, J. J. Mater. Chem. 2010, 33, 6866-6872. [5] Kim, D. K.; Hwang, M.; Lagerwall, J. P. F. J. Polym. Sci. B: Polym. Phys. 2013, 11, 855-867. [6] Reyes C.G., Sharma A.; Lagerwall, J. P. F. Liquid Crystals, 2016, 43, 1986-2001.

Resume : The electrospinning technique is a reliable and low cost method that has been broadly used in the fabrication of nanofibers for intelligent textiles, filters and bone scaffolds to mention some of its applications. This work is intended to use organic semiconductor polymers for electronic device fabrication that goes from diodes to sensors. These organic polymers have been noted to have excellent thermal stability, electrical conductivity, mechanical flexibility and chemical/biological functionality. The p-doped Poly(3-hexylthiophene-2,5-diyl) (P3HT) regioregular and the n-doped Poly(benzimidazobenzophenanthroline) (BBL) are studied in this work. Under a coaxial structure, P3HT as the core and BBL as the sheath of the nanofibers will form a cylindrical p – n junction. This research looks forward to expand the knowledge in organic polymeric semiconductors for efficient flexible arrays with better performance and lower power requirements as well as advancing the electrospinning technique. This process will help establish a reliable procedure for a predictable formation of the coaxial electrospinning set up for organic semiconductors.

Resume : We report on printed strain sensors on several meters long PET fibers for integration in textile at large scale. The sensors are made by locally inkjet printing capacitive transducers on cylindrical PET fibers used in industrial textiles. Numerical modelling of the sensors response was developed and supported the optimum design of the devices. Sensor measurements were performed for strains up to 1% and were in agreement with the model. 10 meters long functionalized PET fibers were woven with metallic interconnect fibers using large scale industrial weaving machine and resulted in a 1 m2 smart textile demonstrator. Applications are foreseen in predictive maintenance of industrial textiles or in the automotive industry. The integration of sensors into fabrics based on standard cleanroom processing of devices onto polyimide flat stripes was demonstrated [1]. Flat stripes have shown to not be ideal for weaving in comparison to the use of cylindrical fibers. Moreover, integration was performed on small area due to the production of the stripes limited to the size of silicon wafers. Here we report on the use of inkjet and aerosol jet printing to functionalize locally cylindrical long textile fibers for large area manufacturing of textile. Capacitive strain sensors were designed on PET fibers (=50 to 200 µm). The sensor consists in a stack configuration made of inkjet printed silver electrodes with in-between a parylene layer used as dielectric. When axial deformation occurs, the dimensions of the capacitor are changed resulting in a sensor response. Sensors were fabricated on 10 m long PET fibers Devices were woven to form a 1 m2 smart area in which several of these structures can be implemented in an array. Fibers functionalization and weaving process require optimization to improve the robustness. Proper operation of the fabricated sensors when applying a strain up to 1% as well as the good agreement of the results with the model were demonstrated. The process could be extended to the fabrication of other capacitive (humidity, vapour) sensors as well to the fabrication of other electronic components (resistors and transistors).

Resume : This contribution deals with the development of the fabric-based gas sensor, which is able to detect gases and vapours at room temperature. The sensor platform is constituted from a non-conductive fabric (dimensions of the sensor are 10x15 mm). There were used two kinds of fabrics of different composition and method of production: (i) non-woven textile (70% polyester/30% polyamide (ii) and woven textile (100% polyester). To improve flexibility of the fabric-based sensor, the thermal adhesive film (Sealon Co., Ltd.) was laminated on the back side of the sensor platform. The film was applied via heated roll laminator (model Titan-110) under these conditions: an adhesive bondline temperature of 80°C for 10 sec using 100 kPa pressure. The screen printing technology was used for creation of the carbon interdigital electrodes (IDEs) (the space between electrodes 0.5 mm) on the surface of the sensor. IDEs were realized by a DEK 248 printer. The essential part of the sensor is sensitive layer based on Polymeric Ionic Liquids (PILs), namely Tetrabutyl phosphonium sulfopropylacrylate (P4444SPA) with butyl acrylate (50% molar) as a copolymer. The PILs represent a new class of polymeric materials, which possess the unique properties such as high conductivity, non-volatility, low toxicity and ability to form coatings which can actively respond to external stimuli. Therefore, they are promising materials for e.g. gas sensing. The sensitive layer was realized by application a monomer mixture on the surface of the sensor and subsequently it was polymerized by means of the LMI-6000 Fiber-Lite white light source (~200 kLux) for 30 min. In this study, we investigated the surface morphology of the fabric-based sensor by a Field Emission Scanning Electron Microscope (FESEM), model MIRA LMH. SEM images were obtained at 3kV at various magnifications. The gas sensing characteristics were determined by both DC- and AC-signals. The Sensor DC response SDC was calculated according to the formula: SDC=Rair/Rgas, where Rair is the resistance it the synthetic air and Rgas is resistance in the atmosphere containing detected gas. The results of AC-measurements were presented as Nyquist plots. The sensor response was tested to 10 ppm of four toxic gases or simulants of chemical warfare agents (methanol, nitrogen dioxide, diethyl malonate, 4-bromacetophenone). The best achieved DC-response was SDC=1.8 to 10 ppm of 4-bromacetophenone (tear gas). This fabric-based sensor with a sensitive layer based on PILs is promising for use in military, security and industrial applications.

Resume : We demonstrate electrical valve for microfluidic systems that utilize a new phenomenon: electrowetting through textiles. We show the fabrication of valves that are fabricated using electrically conductive, and insulated, hydrophobic textiles. When the valve is closed, the liquid cannot pass through the hydrophobic textile mesh; upon application of a potential (100 - 1000 Volts) between the textile and the liquid, the valve opens and the liquid penetrates the electrically conductive mesh (under the influence of electrowetting). These valves have six noteworthy characteristics: i) They are controlled electronically (e.g., require no mechanical or moving parts). ii) They are simple and inexpensive to fabricate. iii) They can work using numerous different mesh materials. v) They operate rapidly (actuate in < 1s). v) They work with a variety of aqueous solutions including low-surface-tension liquids, and bioanalytes including blood. vi) They can easily be integrated with other thin sheet materials (such as paper) by stacking. We used these new capabilities, to demonstrate that complex electronic and fluidic ("electrofluidic") circuits can be designed and fabricated by printing, and stacking of paper and textiles. These textile-based electrofluidic circuits are capable of complex operation such as fluid logic operations or autonomous timing for controlling liquids. Paper microfluidics is currently being explored for many diagnostics application (e.g. for electroanalytical devices, protein detection, and molecular diagnostics), and yet no simple electrical solution has been presented for controlling ("valving") the flow of liquids in paper diagnostics. We, therefore, believe that electrofluidic circuits can find many uses for diagnostics.

Resume : A wide range of materials and design concepts are now available for classes of electronics designed to softly interface with the human body. The same sets of physical properties – thin, lightweight construction and low modulus, elastic mechanics -- that enable these modes of use also facilitate direct integration onto compliant fabric substrates, not only as a convenient mounting location but also as a strategy for enhancing the mechanical robustness of the devices. Work presented in this talk describes the combined use of thin, ultralow modulus, cellular silicone materials with elastic, strain-limiting fabrics, to yield a soft and flexible, but rugged, platform for stretchable electronics. Theoretical and experimental studies highlight the mechanics of adhesion and elastic deformation in these systems and provide design rules for engineering artificial fabric structures with optimized properties. Demonstration examples include wireless electronics for measuring hydration state, electrophysiological activity, motion and blood oximetry.

Resume : Recently, electronic textiles (E-textiles) that various electronic elements are realized in the form of textiles have attracted a lot of interests with development of wearable and stretchable electronics. To successfully achieve the E-textiles, the development of the conductive fiber with high performances is fundamentally essential. Conventional conductive fibers have been mainly fabricated by coating conductive materials on the surface of the fiber or embedding conductive fillers into the elastomeric matrix in the form of fiber. In general, such conductive fibers are hard to achieve high electrical conductivity, stretchability, and stability, simultaneously, due to the limitation in the percolation principle of conductive materials. It is very challenging to significantly advance E-textiles technology unless the performances of the previous conductive fiber is further enhanced. Here, we describe various innovative electronic textiles such as a high-performance textile pressure sensor, strain sensor, and multimodal sensor. For the development of the electronic textile, an superelastic conductive fiber, which effectively overcome the limitations of previous conductive fibers, was first fabricated using the composite of metal nanoparticles and bioinspired elastomeric fibers. The conductive fiber exhibits an excellent conductivity of 20,940 S/cm, superb stretchability of 450 %, and high stability over 10,000 cycles. By using the conductive fiber, various innovative textile mechanical sensors such as a textile pressure sensor, strain sensor, and multimodal sensors were successfully developed. The textile sensors have an unprecedented performances and can be easily integrated into fabrics, gloves, and clothes using a simple sewing method. The textile electronic devices were successfully applied to monitor human motion and operate robots wirelessly.

Resume : Recently, wearable electronics detecting the physiological change for the diagnosis of disease have attracted extensive interests globally. Among them, contact lens is one of the most attractive candidate for the continuous and wireless health monitoring. To realize these personal see-through, devices all device components are required to be transparent and stretchable in order to be integrated into the multiplexed sensor system including wearable soft contact lenses. However, the transparent and stretchable sensors integrated on the biomaterials are not yet been realized. In this talk, we presented an unconventional approach to form transparent, flexible and sensitive multiplexed sensors for diagnosing diabetes and glaucoma based on hybrid nanostructures using one-dimensional metal nanowires and two-dimensional graphene. Additionally, the entirely integrated sensors on the contact lens are designed to be R (resistance) L (inductance) C (capacitance) structure operating via radio frequency for wireless and real-time sensing. In this respect, power sources, associated circuitry, and interconnect electrodes are not required in this system. We further present real-time in-vivo glucose monitoring in rabbit and ex-vivo intraocular pressure sensing in bovine eyeballs wirelessly for applications in wearable electronics. The advance of these electronics using hybrid structures provides a route towards future electronics.

Resume : Textile elettronics is opening an entirely new technological scenario due to the potential of nanomaterials and technologies of endowing textiles with new functionalities without significantly affecting their aesthetic and textile properties. Thanks to this feature, humans will be more integrated with the environment, wearing garments capable of a smart interaction with the surrounding ambient, which is in turn dynamically tailored to the human needs thanks to interior design products based on the proposed technology. Aiming in particular at wearable solutions, textile electronics is a viable solution for a large number of monitoring tasks, for several reasons: textiles are generally low cost, flexible, versatile materials and monitoring several bioparameters by means of devices embedded in textiles is especially attracting for the inherent unobtrusivity of these materials. Starting from a method for making a common textile fibre electrically conductive, we will give a panoramic view of several new functions, going from fibered transistors, to textile sensors. Several examples of fully textile electronic devices will be given, in particular for sensing applications. Our approach allows exploiting textile technology for fabricating a large number of sensing elements arranged in a matrix configuration while dealing with a relatively simple fabrication process that involve only sewing (embroidering) and /or stamping (printing or drop-casting) with polymeric solutions.

Resume : Wearable health monitoring devices are receiving a great deal of interest in medical applications such as monitoring human electrophysiological parameters. Transcutaneous electrophysiology is a one of the most common techniques in both diagnostics and therapy. Due to the fact that this technique is minimally invasive, it is the first method to assess pathologies of the heart and muscles. Poly(3,4- ethylenedioxythiophene (PEDOT) derivatives offer to improve long-term monitoring performance with proven biocompatibility via low skin/electrode interface impedance. Textiles coated with this material have been successfully used as electrodes in cutaneous electrophysiology. Here, we present the evaluation of PEDOT:PSS/textile electrodes in the cutaneous stimulation of muscles as well as the recording of evoked muscular activities. We demonstrate that the textile electrodes have excellent performance in surface electromyography of the lower limb and in stimulating the tibial nerve for eliciting neuromuscular responses. Their comparison with commercial electrode highlights their high performance, enhanced tolerance to noise, valuable comfort in long-term monitoring. This assessment of textile electrodes for capturing of muscular activities paves the way for the integration of conducting polymer-based textile electrodes in wearable transcutaneous electromyography or post-injury rehabilitation.

Resume : The development of wearable chemical sensors is receiving a great deal of attention in view of noninvasive and continuous monitoring of physiological parameters in healthcare applications. This contribution reports on the development of a fully textile, wearable chemical sensor based on an organic electrochemical transistor (OECT) entirely made of conductive polymer (PEDOT:PSS) [Gualandi, Sci. Rep., 6, 33637, 2016]. The active polymer is deposited into the fabric by screen printing processes, thus allowing the device to actually “disappear” into it. We demonstrate the reliability of the textile OECTs as a platform for developing chemical sensors for real-time detection of various redox active molecules (adrenaline, dopamine, ascorbic acid), by assessing their performance in two experimental contexts: i) ideal operation conditions (i.e. totally dipped in an electrolyte solution); ii) real-life operation conditions (i.e. by sequentially adding few drops of electrolyte solution onto only one side of the textile sensor). The OECTs response has also been measured in artificial sweat, assessing how these sensors can be reliably used for the detection of biomarkers in body fluids. Furthermore, we demonstrate the selective detection of dopamine in the presence of interfering compounds (e.g. ascorbic and uric acid) [Gualandi, Sci. Rep. 6, 35419, 2016]. Finally, the very low operating potentials (<1V) and absorbed power (~10−4W) make the here described textile OECTs very appealing for portable and wearable applications.

Resume : There is a trend towards ?intelligent environments? or ?ambient assisted living? where sensors and actuators that surround people or equipment are constantly exchanging information. Such environments require large area carriers for the electronic components ? textile carriers are a good solution due to the large area capability at low cost. They allow the integration of electronic systems in the environment as well as in clothing. Integrating electronics into textiles is still an emerging field. In the development of smart textiles there is a strong drive to go for integration of electronic components into textiles in high volume manufacturing. Different types of smart fabrics, interconnection technologies, and applications have already been developed. But the technologies reported so far have not yet proven to be suited for reliable mass production. Depending on the requirements of the various applications novel concepts are required for the use of conductive textiles as sensors together with the integration of conventional sensors in fabric. New yarns with well defined properties as well as special fabrication processes for the textiles are will be needed to obtain reproducible results. On different levels integration technologies have already been developed and qualified. For very small components a direct integration of chips into the yarn is possible. Larger and more complex modules require specific packages with contacts that allow the interconnection to the yarn ? e.g. crimping, embroidery, soldering, ultrasonic or adhesive bonding. Another alternative is the integration of stretchable interposers on the fabric. For all these solutions the I/O count is limited ? on the one hand due to the limitations of the fabric, on the other hand due to the necessary size of the contacts of the modules. Together the technologies nonetheless build a platform, which allows the realization of a wide range of textile applications.

Resume : Cardiovascular diseases and neurological disorders forms the majority of diseases that need periodic or constant medical attention. Such continuous monitoring requires non-invasive and imperceptible device to prevent a lack of comfort that would impede continuous wearing. For this reason, smart textiles are currently being considered as a relevant solution. Specific reliability issues related to strain during wearing and washing have to be addressed. In this work, we focus on the mechanical reliability of elementary surface mounted devices (such as passives components and microprocessor) on flexible substrates (polyethylene terephthalate and polyimide) embedded onto textile. We developed a specific experimental protocol in order to characterize the radius of curvature of the overall bent system down to few hundreds micrometers through optical measurements. At the same time, in-situ electrical characterizations are correlated to mechanical cycling in order to determine the mechanical reliability of the device. This study also investigate the mechanical behavior of the electrical interconnection between electronics components and conductive tracks. Two kind of interconnections are investigated: soldering with tin-based alloys and gluing with epoxy conductive pastes. Investigating at all levels the mechanical and electrical reliability of flexible electronic under strain points out the influence of the nature and thickness of the substrate on the overall reliability of the device. These results are therefore exploited to build a robust and sustainable solution for a comfortable and continuous monitoring.

Resume : A new class of electronic devices based on stretchable materials can interact with the soft human body in an unprecedented manner. Conductive nanowires embedded in PDMS can be processed using screen-printing or regular photolithography to create stretchable conductive leads down to 10 micrometer resolution. The process parameters, e.g. type of PDMS, nanowire concentration and arrangement allow for precise tailoring of the electrical and mechanical properties of this composite material. Stretchable and biocompatible microelectrode arrays can thus be realized that enable stimulation of intact spinal cord circuits below an injury to control the movement of the limbs aiding rehabilitation and increasing recovery of spinal-cord injured patients. [1,2] The technology also allows for creating devices with up to 500% stretchability or with Gauge factors of over 100. [3] A novel fabrication method has been developed to produce various opto-electronic components using wax-pattern assisted filtration. These devices are soft and made of biocompatible materials therefore they are ideal for in vivo applications. For example, LED and electrode arrays can be used to stimulate the brain of optogenetically modified mice or rats, respectively. [4,5] In addition, smart and passive RFID tags can be created to measure the filing level of the bladder in handicapped users. [6] REFERENCES 1. Electronic dura mater for long-term multimodal neural interfaces I.R. Minev, et al.; Science, 347(6218):159-163, 2015; 2. Stretchable electronics based on Ag-PDMS composites A. Larmagnac et al. Scientific Reports 4: 7254, 2014, DOI:10.1038/srep07254. 3. Stretchable silver nanowire-elastomer composite microelectrodes with tailored electrical properties V. Martinez, et al., ACS Applied Materials & Interfaces, 7 (24):13467–13475. 2015. 4. Fast and efficient fabrication of intrinsically stretchable multilayer circuit boards by wax pattern assisted filtration; K. Tybrandt , J. Vörös; Small 12(2), 180-184, 2016 5. Multilayer Patterning of High Resolution Intrinsically Stretchable Electronics; K. Tybrandt, F. Stauffer, J. Vörös: Scientific Reports 6, 25641 (2016); doi:10.1038/srep25641 6. www.urosense.ch