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Knitted electrodes are a key component to many electronic textiles including sensing devices, such as pressure sensors and heart rate monitors; therefore, it is essential to assess the electrical performance of these knitted electrodes under different mechanical loads to understand their performance during use. The electrical properties of the electrodes could change while deforming, due to an applied load, which could occur in the uniaxial direction (while stretched) or multiaxial direction (while compressed). The properties and performance of the electrodes could also change over time when rubbed against another surface due to the frictional force and generated heat. This work investigates the behavior of a knitted electrode under different loading conditions and after multiple abrasion cycles.
Arash M. Shahidi; Theodore Hughes-Riley; Carlos Oliveira; Tilak Dias. An Investigation of the Physical and Electrical Properties of Knitted Electrodes When Subjected to Multi-Axial Compression and Abrasion. Proceedings 2021, 68, 2 .
AMA StyleArash M. Shahidi, Theodore Hughes-Riley, Carlos Oliveira, Tilak Dias. An Investigation of the Physical and Electrical Properties of Knitted Electrodes When Subjected to Multi-Axial Compression and Abrasion. Proceedings. 2021; 68 (1):2.
Chicago/Turabian StyleArash M. Shahidi; Theodore Hughes-Riley; Carlos Oliveira; Tilak Dias. 2021. "An Investigation of the Physical and Electrical Properties of Knitted Electrodes When Subjected to Multi-Axial Compression and Abrasion." Proceedings 68, no. 1: 2.
The aim of the publication is to report the accuracy, repeatability and the linearity of three commercially available interface pressure measurement systems employed in the treatment of venous disease. The advances in the treatment and management of chronic venous disease by compression therapy have led to considerable research interest in interface pressure measurement systems capable of measuring low-pressure ranges (10–60 mmHg). The application of a graduated pressure profile is key for the treatment of chronic venous disease which is achieved by using compression bandages or stockings; the required pressure profiles are defined in standards (BSI, RAL-GZ, or AFNOR) for different conditions. However, achieving the recommended pressure levels and its accuracy is still deemed to be a challenge. Thus, it is vital to choose a suitable pressure measurement system with high accuracy of interface pressure. The authors investigated the sensing performance of three commercially available different pressure sensors: two pneumatic based (AMI and PicoPress®) and one piezoresistive (FlexiForce®) pressure sensors, with extensive experimental work on their performance in terms of linearity, repeatability, and accuracy. Both pneumatic based pressure measurement systems have shown higher accuracy in comparison to the flexible piezoresistive pressure sensors.
Gayani K. Nandasiri; Arash M. Shahidi; Tilak Dias. Study of Three Interface Pressure Measurement Systems Used in the Treatment of Venous Disease. Sensors 2020, 20, 5777 .
AMA StyleGayani K. Nandasiri, Arash M. Shahidi, Tilak Dias. Study of Three Interface Pressure Measurement Systems Used in the Treatment of Venous Disease. Sensors. 2020; 20 (20):5777.
Chicago/Turabian StyleGayani K. Nandasiri; Arash M. Shahidi; Tilak Dias. 2020. "Study of Three Interface Pressure Measurement Systems Used in the Treatment of Venous Disease." Sensors 20, no. 20: 5777.
Electronically active yarn (E-yarn) pioneered by the Advanced Textiles Research Group of Nottingham Trent University contains a fine conductive copper wire soldered onto a package die, micro-electro-mechanical systems device or flexible circuit. The die or circuit is then held within a protective polymer packaging (micro-pod) and the ensemble is inserted into a textile sheath, forming a flexible yarn with electronic functionality such as sensing or illumination. It is vital to be able to wash E-yarns, so that the textiles into which they are incorporated can be treated as normal consumer products. The wash durability of E-yarns is summarized in this publication. Wash tests followed a modified version of BS EN ISO 6330:2012 procedure 4N. It was observed that E-yarns containing only a fine multi-strand copper wire survived 25 cycles of machine washing and line drying; and between 5 and 15 cycles of machine washing followed by tumble-drying. Four out of five temperature sensing E-yarns (crafted with thermistors) and single pairs of LEDs within E-yarns functioned correctly after 25 cycles of machine washing and line drying. E-yarns that required larger micro-pods (i.e., 4 mm diameter or 9 mm length) were less resilient to washing. Only one out of five acoustic sensing E-yarns (4 mm diameter micro-pod) operated correctly after 20 cycles of washing with either line drying or tumble-drying. Creating an E-yarn with an embedded flexible circuit populated with components also required a relatively large micro-pod (diameter 0.93 mm, length 9.23 mm). Only one embedded circuit functioned after 25 cycles of washing and line drying. The tests showed that E-yarns are suitable for inclusion in textiles that require washing, with some limitations when larger micro-pods were used. Reduction in the circuit’s size and therefore the size of the micro-pod, may increase wash resilience.
Dorothy Anne Hardy; Zahra Rahemtulla; Achala Satharasinghe; Arash Shahidi; Carlos Oliveira; Ioannis Anastasopoulos; Mohamad Nour Nashed; Matholo Kgatuke; Abiodun Komolafe; Russel Torah; John Tudor; Theodore Hughes-Riley; Steve Beeby; Tilak Dias. Wash Testing of Electronic Yarn. Materials 2020, 13, 1228 .
AMA StyleDorothy Anne Hardy, Zahra Rahemtulla, Achala Satharasinghe, Arash Shahidi, Carlos Oliveira, Ioannis Anastasopoulos, Mohamad Nour Nashed, Matholo Kgatuke, Abiodun Komolafe, Russel Torah, John Tudor, Theodore Hughes-Riley, Steve Beeby, Tilak Dias. Wash Testing of Electronic Yarn. Materials. 2020; 13 (5):1228.
Chicago/Turabian StyleDorothy Anne Hardy; Zahra Rahemtulla; Achala Satharasinghe; Arash Shahidi; Carlos Oliveira; Ioannis Anastasopoulos; Mohamad Nour Nashed; Matholo Kgatuke; Abiodun Komolafe; Russel Torah; John Tudor; Theodore Hughes-Riley; Steve Beeby; Tilak Dias. 2020. "Wash Testing of Electronic Yarn." Materials 13, no. 5: 1228.
Silicone-based elastomers saturated with embedded, short-strand fibres are used for their ability to mimic the aesthetic qualities of skin in clinical and theatrical maxillofacial appliance design. Well-known to prostheses fabricators and technicians, the mechanical impact of fibre addition on elastomeric behaviour endures as tacit, embodied knowledge of the craft, almost unknown in the literature. To examine mechanical changes caused by fibre addition, 100 modified polydimethylsiloxane (PDMS) elastomeric compounds containing incremental amounts of loose polyester fibres were prepared and examined in a variety of mechanical tests. It was found that elasticity and strain percentage at breaking point was reduced by increasing fibre content, but Young’s modulus and ultimate tensile strength (UTS) increased. As fibre content was increased, strain hardening was seen at low strain rates, but exaggerated plastic deformation at high strain rates. PDMS hardness increased by 5 degrees of hardness (Shore-00 scale) for every additional percentage of fibres added and a strong positive linear coefficient (0.993 and 0.995) was identified to reach the hardness values given in the literature for living human skin. The apparent reorienting of loose fibres in the PDMS interrupts and absorbs stress during the loading process similar to the organic response to soft tissue loading, except in extension.
Richard Arm; Arash Shahidi; Tilak Dias. Mechanical Behaviour of Silicone Membranes Saturated with Short Strand, Loose Polyester Fibres for Prosthetic and Rehabilitative Surrogate Skin Applications. Materials 2019, 12, 3647 .
AMA StyleRichard Arm, Arash Shahidi, Tilak Dias. Mechanical Behaviour of Silicone Membranes Saturated with Short Strand, Loose Polyester Fibres for Prosthetic and Rehabilitative Surrogate Skin Applications. Materials. 2019; 12 (22):3647.
Chicago/Turabian StyleRichard Arm; Arash Shahidi; Tilak Dias. 2019. "Mechanical Behaviour of Silicone Membranes Saturated with Short Strand, Loose Polyester Fibres for Prosthetic and Rehabilitative Surrogate Skin Applications." Materials 12, no. 22: 3647.
Background and Objectives: Nonintrusive heart rate (HR) monitoring can be a useful tool for health monitoring. By creating capacitively coupled textile electrodes, a comfortable monitoring system can be integrated into seating or bedding that can monitor HR through clothing. This work empirically studied two factors for a system of this type: the electrode size and the material worn by the subject. Materials and Methods: HR measurements were taken using six different sizes of the rectangular textile electrode with four subjects and the signal-to-noise ratio (SNR) of the signals were analyzed. A further set of experiments were conducted with a single subject and a fixed electrode size where different materials were worn. Results: Electrode size was seen to have a statistically insignificant effect on the collected signal quality. The SNR was also largely unaffected by the worn material type. Conclusion: This study provided empirical data relating to two important factors for nonintrusive, textile, and HR monitoring systems. This data will be helpful for designing a seat-based HR monitoring system or to understand the operational limitations of a system of this type.
Theodore Hughes-Riley; Fraser Hill-Casey; Carlos Oliveira; Arash Shahidi; William Hurley; Tilak Dias. Understanding the design rules for a nonintrusive, textile, heart rate monitoring system. Digital Medicine 2019, 5, 162 .
AMA StyleTheodore Hughes-Riley, Fraser Hill-Casey, Carlos Oliveira, Arash Shahidi, William Hurley, Tilak Dias. Understanding the design rules for a nonintrusive, textile, heart rate monitoring system. Digital Medicine. 2019; 5 (4):162.
Chicago/Turabian StyleTheodore Hughes-Riley; Fraser Hill-Casey; Carlos Oliveira; Arash Shahidi; William Hurley; Tilak Dias. 2019. "Understanding the design rules for a nonintrusive, textile, heart rate monitoring system." Digital Medicine 5, no. 4: 162.
A goal in the field of wearable technology is to blend electronics with textile fibers to create garments that drape and conform as normal, with additional functionality provided by the embedded electronics. This can be achieved with electronic yarns (E-yarns), in which electronics are integrated within the fibers of a yarn. A challenge is incorporating non-stretch E-yarns with stretch fabric that is desirable for some applications. To address this challenge, E-yarns containing LEDs were embroidered onto the stretch fabric of a unitard used as part of a carnival costume. A zig-zag pattern of attachment of E-yarns was developed. Tensile testing showed this pattern was successful in preventing breakages within the E-yarns. Use in performance demonstrated that a dancer was unimpeded by the presence of the E-yarns within the unitard, but also a weakness in the junctions between E-yarns was observed, requiring further design work and reinforcement. The level of visibility of the chosen red LEDs within black E-yarns was low. The project demonstrated the feasibility of using E-yarns with stretch fabrics. This will be particularly useful in applications where E-yarns containing sensors are required in close contact with skin to provide meaningful on-body readings, without impeding the wearer.
Dorothy Hardy; Andrea Moneta; Viktorija Sakalyte; Lauren Connolly; Arash Shahidi; Theodore Hughes-Riley. Engineering a Costume for Performance Using Illuminated LED-Yarns. Fibers 2018, 6, 35 .
AMA StyleDorothy Hardy, Andrea Moneta, Viktorija Sakalyte, Lauren Connolly, Arash Shahidi, Theodore Hughes-Riley. Engineering a Costume for Performance Using Illuminated LED-Yarns. Fibers. 2018; 6 (2):35.
Chicago/Turabian StyleDorothy Hardy; Andrea Moneta; Viktorija Sakalyte; Lauren Connolly; Arash Shahidi; Theodore Hughes-Riley. 2018. "Engineering a Costume for Performance Using Illuminated LED-Yarns." Fibers 6, no. 2: 35.