A Transparent Strain Sensor Based on PDMS-Embedded Conductive Fabric for Wearable Sensing Applications
15 Nov 2018-IEEE Access (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 6, pp 71020-71027
TL;DR: A new approach to realize flexible transparent strain sensors through a simple and straightforward layer-by-layer assembly process that combines the use of transparent conductive fabric with polydimethylsiloxane (PDMS) is presented.
Abstract: In this paper, we present a new approach to realize flexible transparent strain sensors. It combines the use of transparent conductive fabric with polydimethylsiloxane (PDMS) through a simple and straightforward layer-by-layer assembly process. The conductive fabric is used to realize the transparent electrodes while the PDMS is utilized as both the substrate and encapsulation layers. As a concept demonstration, an interdigital capacitive sensor is designed and fabricated using the proposed approach. The fabricated sensor is then characterized in terms of its transparency and electro-mechanical nature. This is followed by the application of the sensor in several physiological sensing scenarios, including the sensing of various body-part movements and tactile sensing. Apart from a high optical transparency (~70%), the sensor shows promising sensing results which validate the applicability of the proposed approach for realization of flexible and transparent strain sensors for wearable sensing applications.
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Journal Article•
TL;DR: In this article, a new textile-based strain sensor design was presented and the effect of the base fabric parameters on its sensing properties was analyzed, showing that there is a strong relationship between these parameters and sensor properties.
Abstract: The design and development of textile-based strain sensors has been a focus of research and many investigators have studied this subject. This paper presents a new textile-based strain sensor design and shows the effect of base fabric parameters on its sensing properties. Sensing fabric could be used to measure articulations of the human body in the real environment. The strain sensing fabric was produced by using electronic flat-bed knitting technology; the base fabric was produced with elastomeric yarns in an interlock arrangement and a conductive yarn was embedded in this substrate to create a series of single loop structures. Experimental results show that there is a strong relationship between base fabric parameters and sensor properties.
97 citations
16 Dec 2020
TL;DR: A multifunctional soft sensor capable of decoupling combined deformation modes of stretching, bending, and compression, as well as detecting individual deformed modes, in a compact form factor is reported, which is able to estimate eight different deformation Modes with accuracies higher than 95%.
Abstract: Soft sensors have been playing a crucial role in detecting different types of physical stimuli to part or the entire body of a robot, analogous to mechanoreceptors or proprioceptors in biology. Most of the currently available soft sensors with compact form factors can detect only a single deformation mode at a time due to the limitation in combining multiple sensing mechanisms in a limited space. However, realizing multiple modalities in a soft sensor without increasing its original form factor is beneficial, because even a single input stimulus to a robot may induce a combination of multiple modes of deformation. Here, we report a multifunctional soft sensor capable of decoupling combined deformation modes of stretching, bending, and compression, as well as detecting individual deformation modes, in a compact form factor. The key enabling design feature of the proposed sensor is a combination of heterogeneous sensing mechanisms: optical, microfluidic, and piezoresistive sensing. We characterize the performance on both detection and decoupling of deformation modes, by implementing both a simple algorithm of threshold evaluation and a machine learning technique based on an artificial neural network. The proposed soft sensor is able to estimate eight different deformation modes with accuracies higher than 95%. We lastly demonstrate the potential of the proposed sensor as a method of human-robot interfaces with several application examples highlighting its multifunctionality.
83 citations
TL;DR: A substantial review on the different kinds of strain sensors that have been employed as wearable sensing prototypes and explanation related to the challenges of the current sensors and their futuristic possibilities are presented.
Abstract: The paper presents a substantial review on the different kinds of strain sensors that have been employed as wearable sensing prototypes. The importance of strain sensors lies in their low cost, high sensitivity and multifunctional applications. The flexible strain sensors have been developed with printing techniques that have generated prototypes with varied electrical, mechanical and thermal characteristics. These types of devices have been primarily used for biomedical applications, where a small amount of deflection holds a crucial worth to monitor acute and chronic anomalies in human beings. Among the major areas in healthcare applications where strain sensors have been utilized, wearable sensing holds a pivotal role due to their capability of ubiquitous monitoring. The wearable sensors have been designed and fabricated with a range of processing materials, based on their respective applications. Along with the significant research related to the fabrication and implementation of wearable strain sensors, explanation related to the challenges of the current sensors and their futuristic possibilities have also been showcased in the paper.
62 citations
TL;DR: In this article , a facile and novel fabrication method is proposed for flexible transparent electrodes (FTEs) with an embedded metal mesh via liquid substrateelectric field driven microscale 3D printing process.
Abstract: Flexible transparent electrodes (FTEs) with embedded metal meshes play an indispensable role in many optoelectronic devices due to their excellent mechanical stability and environmental adaptability. However, low‐cost, simple, efficient, and environmental friendly integrated manufacturing of high‐performance embedded metal meshes remains a huge challenge. Here, a facile and novel fabrication method is proposed for FTEs with an embedded metal mesh via liquid substrateelectric‐field‐driven microscale 3D printing process. This direct printing strategy avoids tedious processes and offers low‐cost and high‐volume production, enabling the fabrication of high‐resolution, high‐aspect ratio embedded metal meshes without sacrificing transparency. The final manufactured FTEs with 80 mm × 80 mm embedded metal mesh offers excellent optoelectronic performance with a sheet resistance (Rs) of 6 Ω sq−1 and a transmittance (T) of 85.79%. The embedded metal structure still has excellent mechanical stability and good environmental suitability under different harsh working conditions. The practical feasibility of the FTEs is successfully demonstrated with a thermally driven 4D printing structure and a resistive transparent strain sensor. This method can be used to manufacture large areas with facile, high‐efficiency, low‐cost, and high‐performance FTEs.
57 citations
TL;DR: The design and fabrication of a low-cost and easy-to-fabricate laser-induced graphene sensor together with its implementation for multi-sensing applications and promising sensing results validating the applicability of the fabricated sensor for multiple sensing purposes are presented.
Abstract: The paper presents the design and fabrication of a low-cost and easy-to-fabricate laser-induced graphene sensor together with its implementation for multi-sensing applications. Laser-irradiation of commercial polymer film was applied for photo-thermal generation of graphene. The graphene patterned in an interdigitated shape was transferred onto Kapton sticky tape to form the electrodes of a capacitive sensor. The functionality of the sensor was validated by employing them in electrochemical and strain-sensing scenarios. Impedance spectroscopy was applied to investigate the response of the sensor. For the electrochemical sensing, different concentrations of sodium sulfate were prepared, and the fabricated sensor was used to detect the concentration differences. For the strain sensing, the sensor was deployed for monitoring of human joint movements and tactile sensing. The promising sensing results validating the applicability of the fabricated sensor for multiple sensing purposes are presented.
56 citations
References
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TL;DR: The applicability of the high performance strain sensors based on the nanocomposite of silver nanowire network and PDMS elastomer in the form of the sandwich structure is demonstrated by fabricating a glove integrated with five strain sensors for the motion detection of fingers and control of an avatar in the virtual environment.
Abstract: The demand for flexible and wearable electronic devices is increasing due to their facile interaction with human body. Flexible, stretchable and wearable sensors can be easily mounted on clothing or directly attached onto the body. Especially, highly stretchable and sensitive strain sensors are needed for the human motion detection. Here, we report highly flexible, stretchable and sensitive strain sensors based on the nanocomposite of silver nanowire (AgNW) network and PDMS elastomer in the form of the sandwich structure (i.e., AgNW thin film embedded between two layers of PDMS). The AgNW network-elastomer nanocomposite based strain sensors show strong piezoresistivity with tunable gauge factors in the ranges of 2 to 14 and a high stretchability up to 70%. We demonstrate the applicability of our high performance strain sensors by fabricating a glove integrated with five strain sensors for the motion detection of fingers and control of an avatar in the virtual environment.
1,837 citations
TL;DR: In this article, the authors report an investigation of the variation in the mechanical properties of bulk polydimethylsiloxane (PDMS) elastomers with curing temperature, over the range 25 ◦ C to 200 ¼ C, over a range up to 40% strain and hardness of 44−54 ShA.
Abstract: Polydimethylsiloxane (PDMS) elastomers are extensively used for soft lithographic replication of microstructures in microfluidic and micro-engineering applications. Elastomeric microstructures are commonly required to fulfil an explicit mechanical role and accordingly their mechanical properties can critically affect device performance. The mechanical properties of elastomers are known to vary with both curing and operational temperatures. However, even for the elastomer most commonly employed in microfluidic applications, Sylgard 184, only a very limited range of data exists regarding the variation in mechanical properties of bulk PDMS with curing temperature. We report an investigation of the variation in the mechanical properties of bulk Sylgard 184 with curing temperature, over the range 25 ◦ C to 200 ◦ C. PDMS samples for tensile and compressive testing were fabricated according to ASTM standards. Data obtained indicates variation in mechanical properties due to curing temperature for Young’s modulus of 1.32‐2.97 MPa, ultimate tensile strength of 3.51‐7.65 MPa, compressive modulus of 117.8‐186.9 MPa and ultimate compressive strength of 28.4‐51.7 GPa in a range up to 40% strain and hardness of 44‐54 ShA.
1,218 citations
"A Transparent Strain Sensor Based o..." refers result in this paper
...12 MPa, which is slightly higher than that of the bare PDMS samples reported in [38], i....
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TL;DR: High stretchable multifunctional sensors that can detect strain, pressure, finger touch and finger touch with high sensitivity, fast response time and good pressure mapping function are developed.
Abstract: Considerable efforts have been made to achieve highly sensitive and wearable sensors that can simultaneously detect multiple stimuli such as stretch, pressure, temperature or touch. Here we develop highly stretchable multifunctional sensors that can detect strain (up to 50%), pressure (up to ∼1.2 MPa) and finger touch with high sensitivity, fast response time (∼40 ms) and good pressure mapping function. The reported sensors utilize the capacitive sensing mechanism, where silver nanowires are used as electrodes (conductors) and Ecoflex is used as a dielectric. The silver nanowire electrodes are screen printed. Our sensors have been demonstrated for several wearable applications including monitoring thumb movement, sensing the strain of the knee joint in patellar reflex (knee-jerk) and other human motions such as walking, running and jumping from squatting, illustrating the potential utilities of such sensors in robotic systems, prosthetics, healthcare and flexible touch panels.
896 citations
Additional excerpts
...7 to 1 [3], [4], [7], [9], [10], [29], [30]....
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TL;DR: Transparent strain sensors based on graphene were fabricated in a form of rosette on a flexible plastic or stretchable rubber substrate by using reactive ion etching and stamping techniques.
701 citations
"A Transparent Strain Sensor Based o..." refers background in this paper
...been explored to develop transparent strain sensors, including deposition of graphene [4], metal nanowires [5], [23], carbon nanotubes [7], [15], [21], indium tin oxide films [18], [19], and platinum nanobelts [22] onto stretchable substrates....
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...7 to 1 [3], [4], [7], [9], [10], [29], [30]....
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TL;DR: This paper aims to provide an overview of four emerging unobtrusive and wearable technologies, which are essential to the realization of pervasive health information acquisition, including: 1) unobTrusive sensing methods, 2) smart textile technology, 3) flexible-stretchable-printable electronics, and 4) sensor fusion.
Abstract: The aging population, prevalence of chronic diseases, and outbreaks of infectious diseases are some of the major challenges of our present-day society. To address these unmet healthcare needs, especially for the early prediction and treatment of major diseases, health informatics, which deals with the acquisition, transmission, processing, storage, retrieval, and use of health information, has emerged as an active area of interdisciplinary research. In particular, acquisition of health-related information by unobtrusive sensing and wearable technologies is considered as a cornerstone in health informatics. Sensors can be weaved or integrated into clothing, accessories, and the living environment, such that health information can be acquired seamlessly and pervasively in daily living. Sensors can even be designed as stick-on electronic tattoos or directly printed onto human skin to enable long-term health monitoring. This paper aims to provide an overview of four emerging unobtrusive and wearable technologies, which are essential to the realization of pervasive health information acquisition, including: 1) unobtrusive sensing methods, 2) smart textile technology, 3) flexible-stretchable-printable electronics, and 4) sensor fusion, and then to identify some future directions of research.
647 citations
"A Transparent Strain Sensor Based o..." refers background in this paper
...healthcare systems, where the accurate and efficient acquisition of the physiological parameters of a person in a real-time and unobtrusive manner plays such a pivotal role [1], [2]....
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...Another essential parameter to be considered when it comes to the usage of sensor in wearable application is the unobtrusiveness of the sensor [1], [31], [32]....
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