This paper presents design and batch manufacturing of a highly stretchable textile-silicone capacitive sensor to be used in human articulation detection, soft robotics and exoskeletons. The proposed sensor is made of conductive knit fabric as electrode and silicone elastomer as dielectric. The batch manufacturing technology enables production of large sensor mat and arbitrary shaping of sensors, which is precisely achieved via laser cutting of the sensor mat. Individual capacitive sensors exhibit high linearity, low hysteresis, and a gauge factor of 1.23. Compliant, low profile and robust electrical connections are established by fusing filaments of micro coaxial cable to conductive fabric electrodes of the sensor with thermoplastic film. The capacitive sensors are integrated on a reconstructed glove for monitoring finger motions.

parallel plate capacitive sensing technology is popular due to signal repeatability, temperature insensitivity, and relative simplicity of design and construction. [34,35] In this approach, when an external force is applied to the soft pressure sensor, the dielectric layer thickness of the sensor varies, which leads to a change in the capacitance of the sensor. However, due to relatively small changes in the capacitance of parallel plate sensors under loading, achievable sensitivities are typically very low. [21] Therefore, most studies focus on the modification of the dielectric layer to increase sensitivity. In this context, efforts toward increased sensitivity can be grouped into two main categories: surface modification of the elastomer layers and the creation of micropores within the dielectric layer. In the first approach, topographical features [36][37][38][39][40] (such as nanoscale pyramids, microstructured line patterns, or micrometer-scale circular pillars) are created on the elastomer surface via surface micromachining methods (such as photolithography and molding). However, It should be noted here that, even though high sensitivity can be achieved using surface micromachining, the working range is typically limited to <10 kPa that is undesirable for most wearable applications. The latter approach focuses on the creation of a porous dielectric layer [41][42][43][44] and a recent trend is to use solid particle leaching [44][45][46][47][48] to create micropores within the silicone elastomer. As commercially available sugar cubes and silicone elastomers can be used, manufacturing is quick, simple, and low cost. It has been shown that increased sensitivity over the tactile pressure range was achieved using this method due to the reduced stiffness of the dielectric material as well as increased effective dielectric constant due to the presence of air gaps within the microporous structure. Capacitance values are typically on the order of several femtofarads due to the dielectric layer thickness (height of the sugar cube templates is around 10 mm), but a higher baseline capacitance is needed for sufficient signal-to-noise in the presence of parasitic capacitances within the readout circuitry in these systems. Beside, carbon-based materials, [46] conductive thin films [48] are generally employed to construct electrode layers and are used in combination with the modified dielectric layer for the formation of the soft sensor. However, to integrate these sensors into the system for the creation of wearable electronic devices, the sensors themselves must be flexible, robust, and have mechanically In this paper, the design and manufacturing of a highly sensitive capacitivebased soft pressure sensor for wearable electronics applications are presented. Toward this aim, two types of soft conductive fabrics (knitted and woven), as well as two types of sacrificial particles (sugar granules and salt crystals) to create micropores within the dielectric layer of the capacitive sensor are evaluated, and the combined effec...

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.

This paper presents a study of the sensing properties exhibited by textile-based knitted strain sensors. Knitted sensors were manufactured using flat-bed knitting technology, and electro-mechanical tests were subsequently performed on the specimens using a tensile testing machine to apply strain whilst the sensor was incorporated into a Wheatstone bridge arrangement to allow electrical monitoring. The sensing fabrics were manufactured from silver-plated nylon and elastomeric yarns. The component yarns offered similar diameters, bending characteristics and surface friction, but their production parameters differed in respect of the required yarn input tension, the number of conductive courses in the sensing structure and the elastomeric yarn extension characteristics. Experimental results showed that these manufacturing controls significantly affected the sensing properties of the knitted structures such that the gauge factor values, the working range and the linearity of the sensors varied according to the knitted structure. These results confirm that production parameters play a fundamental role in determining the physical behavior and the sensing properties of knitted sensors. It is thus possible to manipulate the sensing properties of knitted sensors and the sensor response may be engineered by varying the production parameters applied to specific designs.

In this paper, a textile-based strain sensor has been developed to create a respiration belt. The constituent materials and the knitted structure of the textile sensor have been specifically selected and tailored for this application. Electromechanical modeling has been developed by exploiting Peirce's loop model in order to describe the fabric geometry under static and dynamic conditions. Kirchhoff's node and loop equations have been employed to create a generalized solution for the equivalent electrical resistance of the textile sensor for a given knitted loop geometry and for a specified number of loops. A laboratory test setup was built to characterize the prototype sensor and the resulting equivalent resistance under strain levels up to 40%, and consistent resistance response levels have been obtained from the sensor which correlate well with the modelled data. Production of the respiration belt was realized by bringing together knitted sensor and a relatively inelastic textile strap. Both machine simulations and real-time measurements on a human subject have been performed in order to calculate average breathing frequencies under different static and dynamic conditions. Also, different scenarios have been performed, such as slow breathing and rapid breathing. The sensory belt was located in either the chest area or in the abdominal area during the experimental measurements and the sensor yielded a good response under both static and dynamic conditions. However, body motion artefacts affected the signal quality under dynamic conditions and an additional signal-processing step was added to eliminate unwanted interference from the breathing signal.Index Terms-Breathing frequency, conductive yarn, knitted sensor, respiration belt, silver-coated nylon yarn, textile-based strain sensor, electro-mechanical modelling.

Wearable sensing technology is an emerging area and can be utilized for human motion monitoring, physiology monitoring, and human-machine interaction. In this paper, we present a new manufacturing approach to create highly stretchable and soft capacitance-based This article is protected by copyright. All rights reserved.2 strain sensors. This involves a rapid surface modification technique based on direct-write laser rastering to create micro-structured surfaces on pre-strained elastomeric sheets. Then, to

The electronic textile area has gained considerable attention due to its implementation of wearable devices, and soft sensors are the main components of these systems. In this paper, a new sensor design is presented to create stretchable, capacitance-based strain sensors for human motion tracking. This involves the use of stretchable, conductive-knit fabric within the silicone elastomer matrix, as interdigitated electrodes. While conductive fabric creates a secure conductive network for electrodes, a silicone-based matrix provides encapsulation and dimensional-stability to the structure. During the benchtop characterization, sensors show linear output, i.e., R2 = 0.997, with high response time, i.e., 50 ms, and high resolution, i.e., 1.36%. Finally, movement of the knee joint during the different scenarios was successfully recorded.

In this study, weft-knitted strain-sensing structures are described, along with the materials and manufacturing techniques required to produce the fabrics on a computerised flat-bed knitting machine. Knitted sensing fabrics with conductive yarns, i.e. silver-plated nylon yarn and polyester-blended stainless steel yarn have been created with different design possibilities. A laboratory test set-up was built to characterise the knitted sensors and the resulting equivalent resistance under the different level of strains. The most successful samples have been realised through a series of single conductive courses within the interlock base fabric structure using silver-plated nylon in terms of responsivity, repeatability and lower electrical signal drift. Deficiencies associated with strain-sensing structures realised through the intermeshing of conductive yarns have also been addressed.