A Flexible Strain Sensor Based on a Conductive Polymer Composite for in situ Measurement of Parachute Canopy Deformation

A sensor based on a Conductive Polymer Composite (CPC), fully compatible with a textile substrate and its general properties, has been developed in our laboratory, and its electromechanical characterization is presented herein. In particular the effects of strain rate (from 10 to 1,000 mm/min) and of repeated elongation cycles on the sensor behaviour are investigated. The results show that strain rate seems to have little influence on sensor response. When submitted to repeated tensile cycles, the CPC sensor is able to detect accurately fabric deformations over each whole cycle, taking into account the mechanical behaviour of the textile substrate. Complementary information is given concerning the non-effect of aging on the global resistivity of the CPC sensor. Finally, our sensor was tested on a parachute canopy during a real drop test: the canopy fabric deformation during the critical inflation phase was successfully measured, and was found to be less than 9%

An e-learning course on smart textiles enabled by Tritex

In the framework of an interregional project TRITex between Flanders, Belgium and the North of France, an e-learning course on Smart Textiles was developed. The course comprises two modules: Functional and Smart Textile materials and Smart Textile Systems. Because of the cross-border cooperation it is available in two languages: English and French. The course gives the trainee a profound insight in the materials and working principle used to develop smart textiles. It is available 24/7 on the UGent Zephyr platform

Design and Development of a Flexible Strain Sensor for Textile Structures Based on a Conductive Polymer Composite

The aim of this work is to develop a smart flexible sensor adapted to textile structures, able to measure their strain deformations. The sensors are “smart” because of their capacity to adapt to the specific mechanical properties of textile structures that are lightweight, highly flexible, stretchable, elastic, etc. Because of these properties, textile structures are continuously in movement and easily deformed, even under very low stresses. It is therefore important that the integration of a sensor does not modify their general behavior. The material used for the sensor is based on a thermoplastic elastomer (Evoprene)/carbon black nanoparticle composite, and presents general mechanical properties strongly compatible with the textile substrate. Two preparation techniques are investigated: the conventional melt-mixing process, and the solvent process which is found to be more adapted for this particular application. The preparation procedure is fully described, namely the optimization of the process in terms of filler concentration in which the percolation theory aspects have to be considered. The sensor is then integrated on a thin, lightweight Nylon fabric, and the electromechanical characterization is performed to demonstrate the adaptability and the correct functioning of the sensor as a strain gauge on the fabric. A normalized relative resistance is defined in order to characterize the electrical response of the sensor. Finally, the influence of environmental factors, such as temperature and atmospheric humidity, on the sensor performance is investigated. The results show that the sensor’s electrical resistance is particularly affected by humidity. This behavior is discussed in terms of the sensitivity of the carbon black filler particles to the presence of water

Développement d'un système de mesure d'allongement pour voilure de parachute

LILLE1-BU (590092102) / SudocSudocFranceF

Development of a Flexible Strain Sensor Based on PEDOT:PSS for Thin Film Structures

The aim of this study was to develop and optimize a reproducible flexible sensor adapted to thin low-density polyethylene (LDPE) films and/or structures to enable their deformation measurements. As these deformations are suspected to be weak (less than 10%), the developed sensor needs to be particularly sensitive. Moreover, it is of prime importance that sensor integration and usability do not modify the mechanical behavior of its LDPE substrate. The literature review allowed several materials to be investigated and an elastomer/intrinsically conductive polymer PEDOT:PSS (CleviosTM) filled composite was selected to simultaneously combine mechanical properties and electrical conductivity. This composite (made of PEDOT:PSS and silicone Bluesil®) presented satisfying compatibilities with piezoresistive effects, negative temperature performances (in a range from −60 °C to 20 °C), as well as elongation properties (until the elastic limit of the substrate was reached). The method used for creating the sensor is fully described, as are the optimization of the sensor manufacture in terms of used materials, the used amount of materials where the percolation theory aspects must be considered, the adhesion to the substrate, and the manufacturing protocol. Electromechanical characterization was performed to assess the gauge factor (K) of the sensor on its substrate

Design and Development of a Flexible Strain Sensor for Textile Structures Based on a Conductive Polymer Composite

Abstract: The aim of this work is to develop a smart flexible sensor adapted to textile structures, able to measure their strain deformations. The sensors are “smart ” because of their capacity to adapt to the specific mechanical properties of textile structures that are lightweight, highly flexible, stretchable, elastic, etc. Because of these properties, textile structures are continuously in movement and easily deformed, even under very low stresses. It is therefore important that the integration of a sensor does not modify their general behavior. The material used for the sensor is based on a thermoplastic elastomer (Evoprene)/carbon black nanoparticle composite, and presents general mechanical properties strongly compatible with the textile substrate. Two preparation techniques are investigated: the conventional melt-mixing process, and the solvent process which is found to be more adapted for this particular application. The preparation procedure is fully described, namely the optimization of the process in terms of filler concentration in which the percolation theory aspects have to be considered. The sensor is then integrated on a thin, lightweight Nylon fabric, and the electromechanical characterization is performed to demonstrate the adaptability and the correct functioning of the sensor as a strain gauge on the fabric.

Wash Analyses of Flexible and Wearable Printed Circuits for E-Textiles and Their Prediction of Damages

The development of specific user-based wearable smart textiles is gaining interest. The reliability and washability of e-textiles, especially electronic-based components of e-textiles, are under particular investigation nowadays. This is because e-textiles cannot be washed like normal textile products and washing electronic products is not common practice in our daily life. To adopt the e-textile products in our daily life, new standards, based on product usage, should be developed especially for flexibility and washability. The wearable motherboards are the main component for e-textile systems. They should be washing reliable and flexible for better adoption in the system. In this manuscript, flexible wearable PCBs were prepared with different conductive track widths and protected with silicone coatings. The samples were washed for 50 washing cycles in the household washing machine, and provoked damages were investigated. The PCBs were also investigated for bending tests (simulating mechanical stresses in the washing machine), and resultant damages were discussed and co-related with washing damages. The bending test was performed by bending the FPCBs at 90° over the circular rod and under the known hanging load

E-Textile Systems Reliability Assessment—A Miniaturized Accelerometer Used to Investigate Damage during Their Washing

E-textiles reveal a new and hybrid sector of the industry that is created by the integration of electronic components or textile-based electronics in our daily life textile products. They are facing problems in terms of washability, reliability, and user acceptance. This manuscript explains the mechanical stresses acting during the washing process and their impact on e-textile systems. Different washing programs were investigated in terms of total process duration. This washing process duration is mainly divided into three diverse washing actions: low-speed rotation, high-speed rotation, and stop time. This investigation was performed to highlight the importance of the washing actions and their percentages in the total washing process. A piece of fabric with a flexible PCB (printed circuit board), equipped with an accelerometer with a Bluetooth communication device and a microcontroller, was placed in the washing machine to analyze the movement of fabric provoked by washing stresses. The PCB was used for fabric movements recording to determine the impact of mechanical stress on e-textile systems during the washing process. From the video analysis, it was concluded that the duration of the low-speed and high-speed rotation actions should be privileged comparing to the duration of the whole washing process. A power spectral density (PSD) analysis based on the accelerometer outputs was realized. Mechanical stresses at different frequencies were identified. Based on this analysis, it could be possible to improve the protocols of mechanical tests (Martindale and pilling box) used to simulate the mechanical stress applied to e-textile systems during the washing process

Flexible displays for smart clothing: Part II— Electrochromic displays

429-435Chromic materials have the ability to change their colour reversibly according to external environmental conditions. They are categorised by the stimulus that triggers the colour change. For example, thermochromic materials can be defined as those in which a colour change is induced by a change in temperature and electrochromic materials are those in which a colour change is induced when an electrical current is applied. Thermochromism is already a well-known application within the textile field, however electrochromism is not as common. In this paper, an overview of the field of electrochromic devices has been presented and the successful development of a first generation flexible textile electrochromic device, achieved by ourselves, is discussed. The flexible electrochromic textile display consists of a novel 4-layer sandwich structure containing a thin spacer fabric with electrochromic compound (Prussian blue), a conductive layer and two electrodes; bottom and upper (transparent). If powered with a low voltage battery, this structure is able to generate a reversible colour change. The switching times have been measured at ~ 5 s and 4.5 V. The colour changes are monitored via CIE L*, a*, b* values