Compliant Electrodes

In this paper, a pressure sensing device for analysing pressure comfort on elastic garments was designed and developed. The device was calibrated and tested on different compression garments for its reliability. This pressure comfort measurement device is used to measure the pressure between the human body and garments. The fabric resistance due to each and every body movement is noted to evaluate the effect of fabric compression on body muscles in order to assess the pressure comfort for sports persons. The new device proved that elastic garments certainly improve stamina and speed through its quick recovery and lower stress with higher elongation. There is a good correlation found between the pressure values given by the new sensing device and the Instron tester.

The field of electronic textiles is still relatively new and extending due to technology miniaturisation. In this article, the integration of an ultrasonic sensor into a textile structure was realised and analysed in order to develop a system able to help visually impaired people. The performance of ultrasonic sensors was tested by means of five different conductive yarns used as transmission lines, in three different configurations for the purpose of detecting the eventual existing off disturbances and their values. Finally, the influence of the conductive yarn type on the performance of the ultrasonic sensor was discussed. The results highlighted that the linear resistance of conductive yarn has a strong influence on the sensor's signal quality.

Passive smart textiles are the textile structures that can sense stimuli, which may come from mechanical, thermal, electrical, or chemical sources. Textile strain sensors are smart textiles products in which the sensor's resistance changes with applied strain. This study consists in the development of a textile strain sensor and its application on a Multifunctional Intelligent Elbow Brace (MIEB). The hand-knitted sensor was developed using knitting needles. The material used for this sensor was conductive yarn and lycra. The sensor developed was subjected to a stretch recovery test using a universal testing machine,, and the electrical resistance was measured using an electrical multimeter. The sensor developed has good sensing ability against cyclic loading and unloading at a 5%, 20%, 35% strain level. After testing, the sensor was stitched on an elbow brace to develop an MIEB. This study involved the best economical method for measuring the bowling angle of the player using this MIEB without any need for a biomechanical test, which is very expensive. This MIEB can also be used for rehabilitation purposes and for monitoring joint movement.

This is to certify that the thesis entitled "SIMULTANEOUS IMAGE AND SIGNAL ACQUISITION FOR FOOT FORCE ANALYSIS" submitted by MR. ANUP PURI in partial fulfilment of the requirements for the degree of Bachelor of Technology in Biomedical Engineering embodies the bonafide work done by him in the final semester of his degree under the supervision of the undersigned. The thesis or any part of it has not been submitted earlier to any other University / Institute for the award of any Degree or Diploma.

The exposure to extreme temperatures in workplaces involves physical hazards for workers. A poorly acclimated worker may have lower performance and vigilance and therefore may be more exposed to accidents and injuries. Due to the incompatibility of the existing standards implemented in some workplaces and the lack of thermoregulation in many types of protective equipment that are commonly fabricated using various types of polymeric materials, thermal stress remains one of the most frequent physical hazards in many work sectors. However, many of these problems can be overcome with the use of smart textile technologies that enable intelligent thermoregulation in personal protective equipment. Being based on conductive and functional polymeric materials, smart textiles can detect many external stimuli and react to them. Interconnected sensors and actuators that interact and react to existing risks can provide the wearer with increased safety, protection, and comfort. Thus, the skills o...

Interviews from strength and conditioning coaches across all levels of athletic competition identified their two biggest concerns with the current state of wearable technology: (a) the lack of solutions that accurately capture data "from the ground up" and (b) the lack of trust due to inconsistent measurements. The purpose of this research is to investigate the use of liquid metal sensors, specifically Liquid Wire sensors, as a potential solution for accurately capturing ankle complex movements such as plantar flexion, dorsiflexion, inversion, and eversion. Sensor stretch linearity was validated using a Micro-Ohm Meter and a Wheatstone bridge circuit. Sensors made from different substrates were also tested and discovered to be linear at multiple temperatures. An ankle complex model and computing unit for measuring resistance values were developed to determine sensor output based on simulated plantar flexion movement. The sensors were found to have a significant relationshi...

Smart textiles have attracted huge attention due to their potential applications for ease of life. Recently, smart textiles have been produced by means of incorporation of electronic components onto/into conductive metallic yarns. The development, characterizations, and electro-mechanical testing of surface mounted electronic device (SMD) integrated E-yarns is still limited. There is a vulnerability to short circuits as non-filament conductive yarns have protruding fibers. It is important to determine the best construction method and study the factors that influence the textile properties of the base yarn. This paper investigated the effects of different external factors, namely, strain, solder pad size, temperature, abrasion, and washing on the electrical resistance of SMD integrated silver-coated Vectran (SCV) yarn. For this, a Vectran E-yarn was fabricated by integrating the SMD resistor into a SCV yarn by applying a vapor phase reflow soldering method. The results showed that th...

Textiles enhanced with thin-film flexible sensors are well-suited for unobtrusive monitoring of skin parameters due to the sensors’ high conformability. These sensors can be damaged if they are attached to the surface of the textile, also affecting the textiles’ aesthetics and feel. We investigate the effect of embedding flexible temperature sensors within textile yarns, which adds a layer of protection to the sensor. Industrial yarn manufacturing techniques including knit braiding, braiding, and double covering were utilised to identify an appropriate incorporation technique. The thermal time constants recorded by all three sensing yarns was <10 s. Simultaneously, effective sensitivity only decreased by a maximum of 14% compared to the uncovered sensor. This is due to the sensor being positioned within the yarn instead of being in direct contact with the measured surface. These sensor yarns were not affected by bending and produced repeatable measurements. The double covering me...

A variety of sensing technologies have been proposed to measure loading on the plantar surface of the human foot. The majority have a single measurement axis, and few are designed with multiple measurement axes capable of monitoring normal and shear stress. This paper proposes a low cost, biocompatible triaxial piezoresistive sensor that can be implemented with a simple fabrication using inexpensive equipment. The sensor can detect pressures from 0-800kPa with high response and recovery with minimum hysteresis and repeatable results for more than 100 cycles.

The creation of fabrics capable of dynamically communicating information would have a great impact on future smart fabric technologies for applications ranging from fashion and entertainment to biomedical monitoring. Typically, state-of-the-art displays are fabricated onto flexible substrates and then mounted onto textiles. However, recent progress in fabricating electroluminescent fiber shaped devices that can be directly integrated into knitted and woven structure has unlocked new opportunities for developing fabric-integrated displays. Here, a novel method of directly integrating an electroluminescent (EL) system into a network of fibers to create a dynamic knit display is presented. A 4-pixel prototype with individually controllable pixels disposed within a knitted fabric matrix is demonstrated. The control system and structure of isolated pixels in the knit fabric matrix are explained. Important display features based on the prototype performance that demonstrate the current and future potential of this structure are reported.

The creation of fabrics capable of dynamically communicating information would have a great impact on future smart fabric technologies for applications ranging from fashion and entertainment to biomedical monitoring. Typically, state-of-the-art displays are fabricated onto flexible substrates and then mounted onto textiles. However, recent progress in fabricating electroluminescent fiber shaped devices that can be directly integrated into knitted and woven structure has unlocked new opportunities for developing fabric-integrated displays. Here, a novel method of directly integrating an electroluminescent (EL) system into a network of fibers to create a dynamic knit display is presented. A 4-pixel prototype with individually controllable pixels disposed within a knitted fabric matrix is demonstrated. The control system and structure of isolated pixels in the knit fabric matrix are explained. Important display features based on the prototype performance that demonstrate the current and future potential of this structure are reported.

Knitting a thin insulated metal wire simultaneously with elastic yarn in the round creates a coil with a self-inductance close to a wound coil. This knit is flexible and can be stretched, allowing the diameter of the coil to change, resulting in a change of its self-inductance. It is found that rib stitch gives the highest inductance but stocking stitch gives the highest variation of self-inductance with changing diameter. The feasibility of using the knitted coil for inductive plethysmography is demonstrated by simulated breathing in a baby jumper with knitted coils.

I want to thank Professor Kari Halonen for the opportunity to work with interesting topics in his research group and providing me with an intriguing topic for my master's thesis. I also want to thank my two advisors, post doctoral researcher Elina Ilén for her insight in textiles and assistant professor Ivan Vujaklija for his expertise in electromyography and data classification. A big thank you to my colleague Samu Järvinen as well for collaborating with me in this project. I also had a great deal of help and support from my spouse Lauri who has an abundance of medical literature and knowledge and my sister Elsa who lent me a hand when mine was not working.

Over the past few years, alternative power supplies to either supplement or replace batteries for electronic textile and wearable applications have been sought, with the development of wearable solar energy harvesting systems gaining significant interest. In a previous publication the authors reported a novel concept to craft a yarn capable of harvesting solar energy by embedding miniature solar cells within the fibers of a yarn (solar electronic yarns). The aim of this publication is to report the development of a large-area textile solar panel. This study first characterized the solar electronic yarns, and then analyzed the solar electronic yarns once woven into double cloth woven textiles; as part of this study, the effect of different numbers of covering warp yarns on the performance of the embedded solar cells was explored. Finally, a larger woven textile solar panel (510 mm × 270 mm) was constructed and tested under different light intensities. It was observed that a PMAX = 33...

Electronic yarns (E-yarns) contain electronics fully incorporated into the yarn’s structure prior to textile or garment production. They consist of a conductive core made from a flexible, multi-strand copper wire onto which semiconductor dies or MEMS (microelectromechanical systems) are soldered. The device and solder joints are then encapsulated within a resin micro-pod, which is subsequently surrounded by a textile sheath, which also covers the copper wires. The encapsulation of semiconductor dies or MEMS devices within the resin polymer micro-pod is a critical component of the fabrication process, as the micro-pod protects the dies from mechanical and chemical stresses, and hermetically seals the device, which makes the E-yarn washable. The process of manufacturing E-yarns requires automation to increase production speeds and to ensure consistency of the micro-pod structure. The design and development of a semi-automated encapsulation unit used to fabricate the micro-pods is pres...

Fully printed primary zinc-manganese dioxide (Zn|MnO2) batteries in coplanar configuration were fabricated by sequential screen printing. While electrode dimensions and transferred active masses were kept at constant levels, electrode separating gaps were incrementally enlarged from 1 mm to 5 mm. Calendering of solely zinc anodes increased interparticle contact of active material within the electrodes while the porosity of manganese dioxide based electrodes was maintained by non-calendering. Chronopotentiometry revealed areal capacities for coplanar batteries up to 2.8 mAh cm-2. Galvanostatic electrochemical impedance spectroscopy (GEIS) measurements and short circuit measurements were used to comprehensively characterise the effect of gap width extension on bulk electrolyte resistance and charge transfer resistance values. Linear relationships between nominal gap widths, short circuit currents and internal resistances were evidenced, but showed only minor impact on actual discharge capacities. The findings contradict previous assumptions to minimise gap widths of printed coplanar batteries to a sub-millimetre range in order to retain useful discharge capacities. The results presented in this study may facilitate process transfer of printed batteries to an industrial environment.

This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by the Institutional Review Board under Protocol No. IRB-17-725, and performed in line with the Declaration of Helsinki.

The physical interaction of robots with its environment requires a touch sensory system to function effectively. This sensory system measures the robot-environment interactive force & pressure information that can be converted to electrical signals. We fabricated and compared a series of of electronic textile (e-textile) tactile sensors using flexible piezoresistive materials and two types of conductive textile materials with varying layer constructions. Compared with conventional rigid counterparts, the tactile sensors have advantages in terms of lightweight, flexible simple design, high sensitivity, low power consumption and stretchable, and thus is operable at varying curvy surfaces and dynamic forces.

In this paper a stain sensor to measure large strain (80%) in textiles is presented. It consists of a mixture of 50wt-% thermoplastic elastomer (TPE) and 50wt-% carbon black particles and is fiber-shaped with a diameter of 0.315mm. The attachment of the sensor to the textile is realized using a silicone film. This sensor configuration was characterized using a strain tester and measuring the resistance (extension-retraction cycles): It showed a linear resistance response to strain, a small hysteresis, no ageing effects and a small dependance on the strain velocity. The total mean error caused by all these effects was ±5.5% in strain. Washing several times in a conventional washing machine did not influence the sensor properties. The paper finishes by showing an example application where 21 strain sensors were integrated into a catsuit. With this garment, 27 upper body postures could be recognized with an accuracy of 97%.

Loctite photopatternable adhesives 3108, 3340, and 3525 are introduced for MEMS applications. These materials are patterned within minutes by exposure to UV light followed by rinsing with a solvent; no further processing is required. Because the uncured fluid is relatively insensitive to room light, this can be done on any lab bench without the requirement for a clean room. The materials can be spin-coated to obtain films, or cast between spacers for layers up to 1 cm thick, and the cured polymers Reduction in a Urethane Matrix," Smart Mater. Struct.

It remains important to maximize energy density of wearable batteries. In addition, such batteries should be compliant, safe, and environmentally sustainable. Intrinsically safe zinc-manganese dioxide (Zn/MnO 2) batteries are great candidates for powering wearables. However, achieving flexibility of these systems is hindered by the absence of a binder that ensures mechanical integrity of the MnO 2 electrode composite. Herein, a unique approach to fabricate a mechanically robust MnO 2 electrode is presented. Polyvinyl alcohol (PVA)/ polyacrylic acid (PAA) gel cross-linked in situ via thermal treatment is used as a binder for the electrode. Furthermore, energy density and rate capability of the printed battery electrodes are improved by replacing graphite with single-walled carbon nanotubes (CNTs). The batteries retain 93% capacity when the discharge rate is increased from C/10 to C/3, as well as 97% of their capacity after being flexed. In contrast, batteries based on conventional composition retain 60% and 23% of the capacity, respectively. Finally, the battery with the modified electrode has high areal energy density of 4.8 mWh cm À2 and volumetric energy density of 320 mWh cm À3. Fabricating electronics in a flexible wearable format has significant advantages for health monitoring and sensing. [1-5] High-fidelity sensor-skin interfaces improve signal-to-noise ratio through the intimate contact of the device and body. [1,6,7] In addition, ability to wear the devices directly on the skin can enable continuous monitoring of metabolites in bodily fluids like sweat. [8-11] Standalone operation of such electronic systems cannot be realized without power source, such as a battery. [12-15] If the battery is not equally compliant, it will negate the advantages of these flexible devices. Thus, flexible batteries play an important role in achieving the vision of wearable and conforming electronics. In addition to being compliant, such a battery has to meet the energy and power requirements of the wearable systems, to be safe and environmentally sustainable. Batteries based on zinc (Zn) are widely explored for powering wearable devices, due to high safety and environmental friendliness. Zn-air being one of the attractive options, due to its high theoretical energy density. [16,17] Innovations in materials' design were used to achieve good electrochemical and mechanical performance of these batteries. Up-to-date, growing catalyst nanomaterials onto the carbon cloths, [18-21] carbon fiber films, [22,23] nanowire arrays, [24] graphene materials, [25,26] and carbon nanotube (CNT) structures [27-29] have been demonstrated. These approaches enable freestanding flexible electrodes and also ensure high accessibility of catalytic sites and a low contact resistance. Among mainstream battery chemistries with low-cost and well-established material production routs, zinc-manganese dioxide (Zn/MnO 2) is well suited for the purpose. [16] Due to its characteristics such as low material costs, high energy density, and exceptional safety, it has been widely commercialized in the rigid cylindrical format by Duracell ® , for example. In a commercial system, Zn paste and MnO 2 paste are tightly packed in the can, which serves a dual function of casing and a current collector. Once removed from the rigid can, such paste-like electrodes disintegrate. Thus, achieving flexibility of Zn/MnO 2 system requires new engineering approaches. To date, there have been few demonstrations of flexible Zn/MnO 2 batteries. [15,30-42] Several used commercially available materials with innovative components revolving around device design, [15,30-33,37-39] whereas other relied on the novel materials' synthesis, where materials are intrinsically flexible. [34-36] Zhi et al. demonstrated innovative approaches to fabricate rechargeable Zn/MnO 2 batteries for wearables. [40-42] Batteries

It remains important to maximize energy density of wearable batteries. In addition, such batteries should be compliant, safe, and environmentally sustainable. Intrinsically safe zinc-manganese dioxide (Zn/MnO 2) batteries are great candidates for powering wearables. However, achieving flexibility of these systems is hindered by the absence of a binder that ensures mechanical integrity of the MnO 2 electrode composite. Herein, a unique approach to fabricate a mechanically robust MnO 2 electrode is presented. Polyvinyl alcohol (PVA)/ polyacrylic acid (PAA) gel cross-linked in situ via thermal treatment is used as a binder for the electrode. Furthermore, energy density and rate capability of the printed battery electrodes are improved by replacing graphite with single-walled carbon nanotubes (CNTs). The batteries retain 93% capacity when the discharge rate is increased from C/10 to C/3, as well as 97% of their capacity after being flexed. In contrast, batteries based on conventional composition retain 60% and 23% of the capacity, respectively. Finally, the battery with the modified electrode has high areal energy density of 4.8 mWh cm À2 and volumetric energy density of 320 mWh cm À3. Fabricating electronics in a flexible wearable format has significant advantages for health monitoring and sensing. [1-5] High-fidelity sensor-skin interfaces improve signal-to-noise ratio through the intimate contact of the device and body. [1,6,7] In addition, ability to wear the devices directly on the skin can enable continuous monitoring of metabolites in bodily fluids like sweat. [8-11] Standalone operation of such electronic systems cannot be realized without power source, such as a battery. [12-15] If the battery is not equally compliant, it will negate the advantages of these flexible devices. Thus, flexible batteries play an important role in achieving the vision of wearable and conforming electronics. In addition to being compliant, such a battery has to meet the energy and power requirements of the wearable systems, to be safe and environmentally sustainable. Batteries based on zinc (Zn) are widely explored for powering wearable devices, due to high safety and environmental friendliness. Zn-air being one of the attractive options, due to its high theoretical energy density. [16,17] Innovations in materials' design were used to achieve good electrochemical and mechanical performance of these batteries. Up-to-date, growing catalyst nanomaterials onto the carbon cloths, [18-21] carbon fiber films, [22,23] nanowire arrays, [24] graphene materials, [25,26] and carbon nanotube (CNT) structures [27-29] have been demonstrated. These approaches enable freestanding flexible electrodes and also ensure high accessibility of catalytic sites and a low contact resistance. Among mainstream battery chemistries with low-cost and well-established material production routs, zinc-manganese dioxide (Zn/MnO 2) is well suited for the purpose. [16] Due to its characteristics such as low material costs, high energy density, and exceptional safety, it has been widely commercialized in the rigid cylindrical format by Duracell ® , for example. In a commercial system, Zn paste and MnO 2 paste are tightly packed in the can, which serves a dual function of casing and a current collector. Once removed from the rigid can, such paste-like electrodes disintegrate. Thus, achieving flexibility of Zn/MnO 2 system requires new engineering approaches. To date, there have been few demonstrations of flexible Zn/MnO 2 batteries. [15,30-42] Several used commercially available materials with innovative components revolving around device design, [15,30-33,37-39] whereas other relied on the novel materials' synthesis, where materials are intrinsically flexible. [34-36] Zhi et al. demonstrated innovative approaches to fabricate rechargeable Zn/MnO 2 batteries for wearables. [40-42] Batteries

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

This research study investigates the impact of various insulating textile materials on the performance of smart textile pressure sensors made of conductive threads and piezo resistive material. We designed four sets of identical textile-based pressure sensors each of them integrating a different insulating textile substrate material. Each of these sensors underwent a series of tests that linearly increased and decreased a uniform pressure perpendicular to the surface of the sensors. The controlled change of the integration layer altered the characteristics of the pressure sensors including both the sensitivity and pressure ranges. Our experiments highlighted that the manufacturing design technique of textile material has a significant impact on the sensor; with evidence of reproducibility values directly relating to fabric dimensional stability and elasticity.

Highlights • Knitted coils in which a thin insulated Cu wire is knitted simultaneously with yarn gives supple, wearable garments for non-invasive inductive measurements of diameter changes. • The variation of the self-inductance with diameter of knitted coils is linear. • The sensitivity of a knitted wearable coil with thin insulated Cu wire and elastic viscose is ΔL/ΔD = 0.84 µH/cm (L: self-inductance and D: diameter). • Knitted coils in 1/1 rib stitch have the highest self-inductance for a given, supported, nonstretched diameter, independent of yarn type.

This paper presents a retrospective of the benchmark testing methodologies developed and accumulated into the stretch sensor tool kit (SSTK) by the research team during the Closing the Wearable Gap series of studies. The techniques developed to validate stretchable soft robotic sensors (SRS) as a means for collecting human kinetic and kinematic data at the foot-ankle complex and at the wrist are reviewed. Lessons learned from past experiments are addressed, as well as what comprises the current SSTK based on what the researchers learned over the course of multiple studies. Three core components of the SSTK are featured: (a) material testing tools, (b) data analysis software, and (c) data collection devices. Results collected indicate that the stretch sensors are a viable means for predicting kinematic data based on the most recent gait analysis study conducted by the researchers (average root mean squared error or RMSE = 3.63°). With the aid of SSTK defined in this study summary and...

Interviews from strength and conditioning coaches across all levels of athletic competition identified their two biggest concerns with the current state of wearable technology: (a) the lack of solutions that accurately capture data "from the ground up" and (b) the lack of trust due to inconsistent measurements. The purpose of this research is to investigate the use of liquid metal sensors, specifically Liquid Wire sensors, as a potential solution for accurately capturing ankle complex movements such as plantar flexion, dorsiflexion, inversion, and eversion. Sensor stretch linearity was validated using a Micro-Ohm Meter and a Wheatstone bridge circuit. Sensors made from different substrates were also tested and discovered to be linear at multiple temperatures. An ankle complex model and computing unit for measuring resistance values were developed to determine sensor output based on simulated plantar flexion movement. The sensors were found to have a significant relationshi...

The combination of flexible-printed substrates and conventional electronics leads to flexible hybrid electronics. When fabrics are used as flexible substrates, two kinds of problems arise. The first type is related to the printing of the tracks of the corresponding circuit. The second one concerns the incorporation of conventional electronic devices, such as integrated circuits, on the textile substrate. Regarding the printing of tracks, this work studies the optimal design parameters of screen-printed silver tracks on textiles focused on printing an electronic circuit on a textile substrate. Several patterns of different widths and gaps between tracks were tested in order to find the best design parameters for some footprint configurations. With respect to the incorporation of devices on textile substrates, the paper analyzes the soldering of surface mount devices on fabric substrates. Due to the substrate’s nature, low soldering temperatures must be used to avoid deformations or d...

Loctite photopatternable adhesives 3108, 3340, and 3525 are introduced for MEMS applications. These materials are patterned within minutes by exposure to UV light followed by rinsing with a solvent; no further processing is required. Because the uncured fluid is relatively insensitive to room light, this can be done on any lab bench without the requirement for a clean room. The materials can be spin-coated to obtain films, or cast between spacers for layers up to 1 cm thick, and the cured polymers Reduction in a Urethane Matrix," Smart Mater. Struct.

The integration of electronic components in/onto conductive textile yarns without compromising textile qualities such as flexibility, conformability, heat and moisture transfer, and wash resistance is essential to ensuring acceptance of electronic textiles. One solution is creating flexible and stretchable conductive yarns that contain tiny surface-mounted electronic elements embedded at the fiber level. The purpose of this work was to manufacture and subsequently evaluate the physical features and electromechanical properties of stainless steel yarn with light-emitting surface mounted devices (SMDs) embedded in it. The SMDs were successfully integrated into a conductive stainless steel yarn (SS) by inserting crimp beads and creating a bond through hot air soldering machines, resulting in what we call an E-yarn. The relationship curves between gauge length and electrical resistance, and the relationship curves between conductive yarn elongation and electrical resistance, were explor...

Smart textiles have attracted huge attention due to their potential applications for ease of life. Recently, smart textiles have been produced by means of incorporation of electronic components onto/into conductive metallic yarns. The development, characterizations, and electro-mechanical testing of surface mounted electronic device (SMD) integrated E-yarns is still limited. There is a vulnerability to short circuits as non-filament conductive yarns have protruding fibers. It is important to determine the best construction method and study the factors that influence the textile properties of the base yarn. This paper investigated the effects of different external factors, namely, strain, solder pad size, temperature, abrasion, and washing on the electrical resistance of SMD integrated silver-coated Vectran (SCV) yarn. For this, a Vectran E-yarn was fabricated by integrating the SMD resistor into a SCV yarn by applying a vapor phase reflow soldering method. The results showed that th...

With huge varieties of fabrics, the first challenge for any performance evaluation is to categorize the vast types of the products into fewer, more homogeneous and thus akin groups. Classification or sorting is arguably the first step of any scientific investigation, and comparison of product quality is meaningful only when conducted within a group of comparable products. A new criterion termed fabric linear density λ is first proposed in this paper so that fabrics can in general be divided into 4 groups. The derivation and validation of this parameter are provided.  The importance of fabric drape is almost self-evident, but there is still no effective ways to measure this fabric attribute. The Cusick Drapemeter suffers from its low repeatability and low sensitivity, and is hence not widely or frequently used. The PhabrOmeter, along with the fabric linear density λ, is proposed and demonstrated in this study as a much more efficient alternative for fabric drape te...

Smart textiles have attracted huge attention due to their potential applications for ease of life. Recently, smart textiles have been produced by means of incorporation of electronic components onto/into conductive metallic yarns. The development, characterizations, and electro-mechanical testing of surface mounted electronic device (SMD) integrated E-yarns is still limited. There is a vulnerability to short circuits as non-filament conductive yarns have protruding fibers. It is important to determine the best construction method and study the factors that influence the textile properties of the base yarn. This paper investigated the effects of different external factors, namely, strain, solder pad size, temperature, abrasion, and washing on the electrical resistance of SMD integrated silver-coated Vectran (SCV) yarn. For this, a Vectran E-yarn was fabricated by integrating the SMD resistor into a SCV yarn by applying a vapor phase reflow soldering method. The results showed that th...

This work involved human subjects or animals in its research. Approval of all ethical and experimental procedures and protocols was granted by the Institutional Review Board under Protocol No. IRB-17-725, and performed in line with the Declaration of Helsinki.

This paper presents a retrospective of the benchmark testing methodologies developed and accumulated into the stretch sensor tool kit (SSTK) by the research team during the Closing the Wearable Gap series of studies. The techniques developed to validate stretchable soft robotic sensors (SRS) as a means for collecting human kinetic and kinematic data at the foot-ankle complex and at the wrist are reviewed. Lessons learned from past experiments are addressed, as well as what comprises the current SSTK based on what the researchers learned over the course of multiple studies. Three core components of the SSTK are featured: (a) material testing tools, (b) data analysis software, and (c) data collection devices. Results collected indicate that the stretch sensors are a viable means for predicting kinematic data based on the most recent gait analysis study conducted by the researchers (average root mean squared error or RMSE = 3.63°). With the aid of SSTK defined in this study summary and...

Wearable sensors are beneficial for continuous health monitoring, movement analysis, rehabilitation, evaluation of human performance, and for fall detection. Wearable stretch sensors are increasingly being used for human movement monitoring. Additionally, falls are one of the leading causes of both fatal and nonfatal injuries in the workplace. The use of wearable technology in the workplace could be a successful solution for human movement monitoring and fall detection, especially for high fall-risk occupations. This paper provides an in-depth review of different wearable stretch sensors and summarizes the need for wearable technology in the field of ergonomics and the current wearable devices used for fall detection. Additionally, the paper proposes the use of soft-robotic-stretch (SRS) sensors for human movement monitoring and fall detection. This paper also recapitulates the findings of a series of five published manuscripts from ongoing research that are published as Parts I to ...

WEARPLEX is a multidisciplinary research and innovation action with the overall aim to integrate printed electronics with flexible and wearable textile-based biomedical multi-pad electrodes. It aims to answer the growing need for user-friendly electrodes for pervasive measurement of electrophysiological signals and application of electrical stimulation. It focuses on the development of the printable electronics and manufacturing processes for stretchable textile based multi-pad electrodes with integrated logic circuits that enable a significant increase in the number of electrode pads (channels) and facilitate the creation of new products in the sectors of medical electronics and life-style. The advanced printed electronics integrated in WEARPLEX electrodes will allow the individual pads to be connected in arbitrary configurations to the output leads of the electrode. Therefore, the pads will be flexibly organized into several virtual electrodes of arbitrary position, shape and size...

Novel textile temperature sensors based on strain-relieved braiding constructions offer attractive monitoring possibilities for numerous application fields involving e-textiles in general, and medical textiles in particular. Thus, the research work presented in this paper focused on theoretical foundations, manufacturing, and procedural, mechanical as well as thermal testing of these newly developed, textile-based sensors for temperature measurements. The median basic resistance of the scalable sensor yarns using a helical stainless steel wire is about 0.81 Ω/mm. Within the temperature range of 22 to 40℃, the developed sensor yarn has a mean linearity deviation of 0.028 K. The measured temperature coefficient is 0.68 × 10−3 K−1, which correlates with the properties of the stainless steel wire.

Herein, we have proposed a method that uses a highly stretchable and conductive fiber-based multi-angle fiber array, which precisely measures human joint motion in various degrees of freedom (flexion and rotation) at the shoulders, knees, and wrists in real time. By embedding conductive carbon nanotubes (CNTs) within spandex fibers of high elasticity and shape recovery ratio, we monitored joint motion stably without degrading the fiber’s conductivity even during repeated stretching and contraction of different lengths. The strain occurring in a specific direction was monitored using mapping images generated due to the change in resistance that occurred when 12 CNT-embedded spandex fibers arranged in radial lines at intervals of 15° were stretched or contracted by an external force. The proposed high-precision joint-monitoring technology measures human motion accurately and is applicable for use in wearable healthcare devices that require precise measurements.

Foot ulcers are very common in diabetics due to diabetic neuropathy. This is a condition in which the nerves throughout the body are damaged due to high blood glucose caused by diabetes. Diabetic patients that develop foot ulcers may not even know they have these wounds due to nerve damage in the feet. Because of this, these ulcers will go untreated, leading to infections, and eventually amputation. A specially designed sock lined with pressure sensors that diabetic patients can wear will help with ulcer detection. Using the pressure sensors, the sock will be able to detect changes in pressure given off by the ulcers and then relay a warning message to your smartphone.

We developed a human motion measurement system using textilebased motion sensors whose electrical resistance changes with textile length. Eight body locations were marked and used for measurement, based on previous studies investigating the relationship between human muscles and activities. Five male subjects participated to the experiment, walking and running while the electrical resistance of each sensor was measured. Measuring and analyzing the variations in the electrical resistances of our sensors allowed us to successfully evaluate body postures and motions.