The rapid progress in consuming e-textiles has made a huge uprising in the researcher’s track on the course of smart and functional textile development. Consumption of functional and smart textiles in the wearable e-textile is fetching extra eye-catching scheme owing to its lightweight property, flexibility, stretchability, and the ability to be integrated into wearable apparel. This platform makes wearable e-textile arena to be more user-friendly, but at the same time, it sets a limit to some of the real desires of the tactile comfort during skin contact. So far, many researchers have attempted to provide the consumers with a real sense of ordinary fabric hand through subjective and objective evaluation techniques. However, few or no attempts have been achieved to evaluatethe tactile comfort of functional and smart fabrics.

In this current thesis, we propose for the first time a systematic methodology to study the functional and smart textile fabric's tactile comfort properties through subjective and objective evaluation using skin contact mechanics principle. First, various functional and smart textile fabrics were produced, developed and collected using different state of the art technologies such as 3D printing, coating, inkjet printing, screen printing, incorporation of smart fiber during knitting operation. The samples produced using the above mentioned technologies were thermochromic, conductive, and photochromic type. Then, we investigated the physiological and psychological aspect with regards to the tactile comfort on the basis of visual and blind subjective evaluation for the tactile properties and interpreted utilizing different statistical techniques. Sensory experiments employing a trained panel of experts were carried outto verify the tactile handle. We followed a novel approach to verify the hypothesis obtained from different tactile attributes. From this study, we conclude that it is likely to perceive the tactile comfort properties through visual and blind scenarios.

In order to explore further, objective measurements of tactile properties of the samples were conducted using the Kawabata evaluation system (KES). Low-stress mechanical properties related to the tactile comfort of the fabrics were measured using KES. The KES result confirmed that it is credible to measure the tactile properties using objective evaluation methods to interpret the tactile properties of the samples. Sets of relevant intelligent systems such as fuzzy logic and artificial neural network (ANN) were implemented to interpret and analyze the subjective and objective sensory datasets and to compare the results obtained by both methods.

Subjective and objective evaluations of the handle of textile materials are very important to describe its tactile comfort for next-to-skin goods. In this paper, the applicability of artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) modeling approaches for the prediction of the psychological perceptions of functional fabrics from mechanical properties were investigated. Six distinct functional fabrics were evaluated using human subjects for their tactile score and total hand values (THV) using tactile and comfort-based fabric touch attributes. Then, the measurement of mechanical properties of the same set of samples using KES-FB was performed. The RMSE values for ANN and ANFIS predictions were 0.014 and 0.0122 and are extremely lower than the variations of the perception scores of 0.644 and 0.85 forANN and ANFIS, respectively with fewer prediction errors. The observed results indicated that the predicted tactile score and are almost very close to the actual output obtained using human judgment. Fabric objective measurement-technology, therefore, provides reliable measurement approaches for functional fabric quality inspection, control, and design specification.

Sensory investigations of the functional textiles could be an alternative for the quality-inspection and control of the products. The purpose of this research is to use subjective evaluation technique for assessing the tactile comfort of some functional textile fabrics based on AATCC Evaluation procedure 5-2011. Blind subjective evaluations and visual subjective evaluations were performed for sensory investigation. Ten fabric-skin-contact and comfort-related sensory properties were used to evaluate the handle of the functional textile fabrics. The reliability of the sensorial data obtained by subjective tests was evaluated using statistical data analysis techniques. A minimum and maximum consensus distance recorded were 0.58 and 1.61, respectively, using a descriptive sensory panel analysis and prove the consistency and similar sensorial perception between panelists. The Pearson correlation coefficient between panelists was up to 96% and hence a strong agreement between the panelist’s judgment. The results allowed to consider the subjective evaluation using a panel of experts could be validated in the case of functional fabrics. For functional textiles, additional visual subjective evaluation should be considered to have a similar human perception in addition to blind subjective evaluation.

Consumer preferences for textile products are largely determined by sensory characteristics.  The main aim of this project is to measure the comfort of smart fabric using subjective & objective methods by measuring the tactile sensations arise through the triggering of sensory receptors in or near the skin surface by the contact of the fabric surface with the skin.

The objective data of fabric surface will be acquired by VHX patterns microscope & KES system. Analysis & modelling of mechanical properties smart textiles will be made to study the interaction of fabric with the wearer in terms of tactile properties.

An investigation on the psycho-sensorial comfort will be conducted using subjective methods; the result will be comprehensive list of descriptors for each sensation. By analysing the relation of design factors with the results of quality inspection & evaluation, different combinations of design factors on the requirement of end users will be provided.

Keywords: skin contact mechanics, smart textiles, KES, VHX, human perception

Conductive elastic fabrics are desirable in wearable electronics and related applications. Highly elastic conductive polyamide/lycra knitted fabric was prepared using intrinsically conductive polymer poly (3, 4-ethylenedioxythiophene) (PEDOT) blended with polyelectrolyte poly (styrene sulfonate) (PSS) using easily scalable coating and immersion methods. The effects of these two methods of treatments on uniformity, electromechanical property, stretchability, and durability were investigated. Different grades of waterborne polyurethanes (PU) were employed in different concentrations to improve the coating and adhesion of the PEDOT:PSS on the fabric. The immersion method gave better uniform treatment, high conductivity, and durability against stretching and cyclic tension than the coating process. The surface resistance increased from ~1.7 and ~6.4 Ω/square at 0% PU to ~3.7 and ~12.6 Ω/square at 50% PU for immersion and coating methods, respectively. The treatment methods as well as the acidic PEDOT:PSS did not affect the mechanical properties of the fabric and the fabric show high strain at break of ~650% and remain conductive until break. Finally, to assess the practical applicability of the treated fabric for wearable e-textiles, the change in surface resistance was assessed by cyclically stretching 10 times at 100% strain and washing in a domestic laundry for 10 cycles. The resistance increases only by a small amount when samples were stretched cyclically at 100% strain and the samples show good durability against washing.

Coating of textile fabrics with poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) is one of the methods used for obtaining functional or smart applications. In this work, we prepared PEDOT:PSS polymer with certain additives such as polyethylene glycol (PEG), methanol (MeOH), and ethylene glycol (EG) on polyester fabric substrates by a simple immersion process. Surface resistance was measured and analyzed with analysis of variance to determine the coating parameters at 95% confidence level. Fourier Transform Infrared (FTIR) analysis and Scanning Electron Microscopy (SEM) study of the samples were performed. Contact angle and washing fastness measurements were conducted, to observe the wettability and washing fastness of the samples, respectively. Surface resistance values were decreased by a factor of 100, due to conductive enhancers. As the immersion time and temperature condition varies, surface resistance showed no difference, statistically. FTIR analysis supports the idea that the mechanism responsible for the conductivity enhancement is the partial replacement of PSS from PEDOT chain by forming a hydrogen bond with hydroxyl ion (OH) of the conductive enhancers. A SEM images showed that PEDOT:PSS is well distributed to the surface of the fabrics. Contact angle measurements showed morphology change in the samples. The conductivity was reasonably stable after 10 washing cycles. Altogether, an effective simple immersion of coated polyester fabric is presented to achieve functional textiles that offer a broad range of possible applications.

Coating of textile fabrics with poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) is one of the methods used for obtaining functional or smart applications. In this work, we prepared PEDOT:PSS polymer with certain additives such as polyethylene glycol (PEG), methanol (MeOH), and ethylene glycol (EG) on polyester fabric substrates by a simple immersion process. Surface resistance was measured and analyzed with analysis of variance to determine the coating parameters at 95% confidence level. Fourier Transform Infrared (FTIR) analysis and Scanning Electron Microscopy (SEM) study of the samples were performed. Contact angle and washing fastness measurements were conducted, to observe the wettability and washing fastness of the samples, respectively. Surface resistance values were decreased by a factor of 100, due to conductive enhancers. As the immersion time and temperature condition varies, surface resistance showed no difference, statistically. FTIR analysis supports the idea that the mechanism responsible for the conductivity enhancement is the partial replacement of PSS from PEDOT chain by forming a hydrogen bond with hydroxyl ion (OH) of the conductive enhancers. A SEM images showed that PEDOT:PSS is well distributed to the surface of the fabrics. Contact angle measurements showed morphology change in the samples. The conductivity was reasonably stable after 10 washing cycles. Altogether, an effective simple immersion of coated polyester fabric is presented to achieve functional textiles that offer a broad range of possible applications.

The conductivity of a poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS) film can be enhanced by more than two orders of magnitude with two or more polar groups, such as ethylene glycol, methanol or DMSO [1, 2, 3], when added to an aqueous solution of PEDOT: PSS. The mechanism of this conductivity enhancement was studied. The aim of this paper is to investigate the effects of coating process on the electrical properties of coated polyester fabric substrates. For this paper surface resistance of PEDOT: PSS coated polyester fabric was investigated as a function of immersion time (5 and 15) and drying conditions (Vacuum and no vacuum) by simple treatment with methanol and ethylene glycol. For this, 24 coated fabrics designed with Minitab software (DOE), with three replicates and two levels, were produced by using polyester base fabric and PEDOT: PSS as a conductive polymer to study how after-treatment of PEDOT: PSS coated fabric by ethylene glycol and methanol as a conductive enhancer affects the electrical surface resistance of coated fabric. The electrical resistance of PEDOT: PSS coated fabric were measured before and after chemical treatments. The measured data were evaluated with the design of experiments and analysis of variance to determine the coating parameters at 95% confidence level.

The result of the experiment showed that it is possible to enhance the electrical conductivity of PEDOT: PSS coated textiles by simple after-treatment by using ethylene glycol and methanol as a conductive enhancer. The electrical surface resistance was decreased by a two orders of magnitude when using this method. Altogether, an effective simple treatment of coated polyester fabric was presented to achieve functional textiles that offer a broad range of possible applications.

Tactile comfort has a strong relation with low-stress mechanical properties of textilefabrics having close contact with the human skin. In this work, we attempt to analyse the lowstressmechanical properties of the functional knitted fabric obtained using Kawabata’s fabricevaluation system (KES-FB). The measured results were compared with those of the controlledpolyester fabric. The bending ability of the product increased from 0.2448 to 0.8010gf.cm2/cmand hence the rigidity influenced when copper yarn is introduced. However, thecompressibility increased from 0.173 to 0.449gf.cm/cm2 and hence the compressibility slightlyboosted. The surface roughness (SMD) highly increased from 7.196 to 14.258 μm. It wasobserved that the incorporation of conductive copper yarn during knitting brought an effect onthe tactile comfort of the fabrics and reduced by 69%. The overall comfort properties of theconductive textile fabric were reduced due to the introduction of copper yarn during knittingoperations. Focus should be given when functional fabric developed which has close contact tothe human skin.

One of the challenges in smart textiles is to develop suitable multifunctional materials that can address simultaneously several characteristics such as durability, stretchability, lightweight, and conductivity. Conductive polymers which showed success in different technological fields like polymer solar cells and light emitting diodes are promising in many smart textile applications. In this work, we treated a common polyamide/lycra knitted fabric with PEDOT:PSS for stretchable e-textiles. PEDOT:PSS, with DMSO as a conductivity enhancer and different ratios of water-based polyurethane dispersions as a binder, was applied to the fabric with simple immersion and coating applications. The effect of different application methods and binder ratio on the surface resistance of the fabric was monitored with four point probe electrical surface resistance measurement systems. Samples prepared by immersion technique are more uniform and have higher conductivity than those prepared by a coating technique. SEM images showed that PEDOT:PSS is incorporated into the structure in the immersion method while in the coating it is majorly present on the surface of the fabric. The tensile measurement showed that the acidic PEDOT:PSS and polyurethane dispersion coating has no adverse effect on the tensile strength of the fabric. The coated samples can be stretched up to 700% while still reasonably conductive. The resistance increases only by a small amount when samples were stretched cyclically by stretching 100%. Generally, samples prepared by the immersion method maintained better conductivity while stretching than those by a coating method. The washing fastness of the samples was also assessed.

Electroluminescence (EL) is the property of a semiconductor material pertaining to emitting light in response to an electrical current or a strong electric field. The purpose of this paper is to develop a flexible and lightweight EL device. Thermogravimetric analysis (TGA) measurement was taken to observe the thermal degradation behavior of NinjaFlex. Poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonic acid) (PEDOT:PSS) with ethylene glycol (EG) was coated onto polyester fabric where NinjaFlex was placed onto the coated fabric using three-dimensional (3D) printing and phosphor paste and BendLay filament were coated 3D-printed subsequently. Adhesion strength and flexibility of the 3D-printed NinjaFlex on textile fabrics were investigated. The TGA results of the NinjaFlex depicts that no weight loss was observed up to 150°C. Highly conductive with a surface resistance value of 8.5 ohms/sq., and uniform surface appearance of coated fabric were obtained as measured and observed by using four-probe and scanning electron microscopy (SEM), respectively at 60% PEDOT:PSS. The results of the adhesion test showed that peel strengths of 4160, 3840 N/m were recorded for polyester and cotton specimens, respectively. No weight loss was recorded following three washing cycles of NinjaFlex. The bending lengths were increased by only a factor of 0.082 and 0.577 for polyester and cotton samples at 0.1 mm thickness, respectively; which remains sufficiently flexible to be integrated into textiles. The prototype device emitted light with a 12 V alternating current (AC) power supply. 

Functional finishing brings an alteration on the mechanical and surface properties of textilematerials and henceforth influences the tactile properties. In this work, Kawabata evaluation systems(KES) for fabrics were utilized to notice the changes in the tactile properties of fabrics resultingfrom different finishing types such as inkjet printing, screen printing, and coating. The effects offunctional finishing on the fabric’s tactile property were inconsistent with reference to the courseof decrease or increase being dependent on the types of finishes. The findings showed that KEScan be employed as a promising tool to sort out the suitable functional finishing types in termsof tactile properties. Amongst the implemented finishing types, inkjet printing offered superiortactile properties with respect to tensile energy (softness), shear rigidity, compressional softness,bending stiffness (drapability), and surface properties. The KES results confirmed that low-stressmechanical properties are strongly associated with the tactile property and might assist as a qualityprofile data source for guaranteeing the production and development of a virtuous quality product.The result encourages further utilization of the KES for functional fabric tactile property evaluation.

Research in functional and smart textiles often focuses on technological and scientific challenges, or on the interaction with the wearer in a technological sense, but smaller extent on the interaction of these fabrics with the wearer in terms of tactile sensations. This research focuses on the subjective evaluation of the smart and functional textile fabrics as well as the objective evaluation using Kawabata Evaluation System (KES). A collection of the smart and functional textiles was developed and collected using various state of the art technologies such as 3D printing, inkjet printing, screen printing, and incorporation of smart fibers with knitting. The contact mechanics of these fabrics will be evaluated by subjective hand evaluation to study smart and functional textile fabric sensory properties such smoothness, roughness, softness, prickliness, stretchability, fluffy, sticky, sliding, and other behaviors of the smart fabric when touched with parts of the human finger. Equations will be developed to relate the subjective and objective measurements of the smart textile fabrics. The subjective hand values will be compared further with mechanical properties of the smart fabric such as tensile, bending, shear, compression, and surface friction which will be measured using KES.

Conductive elastic fabrics are desirable in wearable electronics and related applications. Here, we report a highly elastic conductive polyamide/lycra knitted fabric using intrinsically conductive polymer poly (3, 4-ethylenedioxythiophene) (PEDOT) blended with polyelectrolyte poly (styrene sulfonate) (PSS) by easily scalable coating and immersion methods. We investigated the effects of these two methods of treatments on uniformity, electromechanical property, stretchability, and durability. Different grades of waterborne polyurethanes (PU) were employed in different concentrations to improve the coating and adhesion of the PEDOT:PSS on the fabric. The immersion method gave better uniform treatment, higher conductivity, and durability against stretching and cyclic stretching than the coating method. The surface resistance increased from ~1.7 and ~6.4 Ω/sq at 0% PU to ~3.7 and ~12.6 Ω/sq at 50% PU for immersion and coating methods, respectively. The treatment methods as well as the acidic PEDOT:PSS did not affect the mechanical properties of the fabric and the fabric showed high strain at break of ~650% and remain conductive until break. The resistance increased only by a small amount when samples were stretched for 10 cycles at 100% strain and the samples show good durability against 10 domestic laundry washing cycles.

Viscosity and surface tension are the fundamental rheological property of an ink for inkjet printing. In this work, we optimized the viscosity and surface tension of inkjet inks by varying the concentration of glycerol with water, PEDOT-PSS with glycerol and water, finally by adding the surfactant. The surface resistance of the sample was characterized by four-probe measurement principle. The change in volume of PEDOT-PSS in water, as well as the change in weight of glycerol in water has got a great influence on the viscosity on both temperature dependence and shear dependence behaviour of the ink solution. The surface tension of the solution changed from 37 to 28mN/m due to the addition of Triton. Varying the volume of PEDOT-PSS and the volume of glycerol in water has a great influence on the viscosity of the ink solution for inkjet printing. Viscosity drops from 12.5 to 9.5 mPa s with the addition of Triton at 25 ^oC. The PEDOT-PSS solution was found to be temperature dependence but not shear dependence as it is a Newtonian fluid. The sample was used to connect the light emitting diode (LED), and hence the electrical conductivity, with a surface resistance of 0.158 KΩ/square, was sufficient enough to give transfer current for LED lamp. The rheology of the inkjet ink is very critical for the successful droplet formation of the inkjet printing.

This paper aims to predict the hand values (HVs) and total hand values (THVs) of functional fabrics by applying the fuzzy logic model (FLM) and artificial neural network (ANN) model. Functional fabrics were evaluated by trained panels employing subjective evaluation scenarios. Firstly, the FLM was applied to predict the HV from finishing parameters; then, the FLM and ANN model was applied to predict the THV from the HV. The estimation of the FLM on the HV was efficient, as demonstrated by the root mean square error (RMSE) and relative mean percentage error (RMPE); low values were recorded, except those bipolar descriptors whose values are within the lowermost extreme values on the fuzzy model. However, the prediction performance of the FLM and ANN model on THV was effective, where RMSE values of0.21 and 0.13 were obtained, respectively; both values were within the variations of the experiment. The RMPEvalues for both models were less than 10%, indicating that both models are robust, effective, and could be utilized in predicting the THVs of the functional fabrics with very good accuracy. These findings can be judiciously utilized for the selection of suitable engineering specifications and finishing parameters of functional fabrics to attain define tactile comfort properties, as both models were validated using real data obtained by the subjective evaluation of functional fabrics.