Highly Sensitive Textile-Based Capacitive Pressure Sensors Using PVDF-HFP/Ionic Liquid Composite Films.

Textile-based pressure sensors have garnered considerable interest in electronic textiles due to their diverse applications, including human-machine interface and healthcare monitoring systems. We studied a textile-based capacitive pressure sensor array using a poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)/ionic liquid (IL) composite film. By constructing a capacitor structure with Ag-plated conductive fiber electrodes that are embedded in fabrics, a capacitive pressure sensor showing high sensitivity, good operation stability, and a wide sensing range could be created. By optimizing the PVDF-HFP:IL ratio (6.5:3.5), the fabricated textile pressure sensors showed sensitivity of 9.51 kPa-1 and 0.69 kPa-1 in the pressure ranges of 0-20 kPa and 20-100 kPa, respectively. The pressure-dependent capacitance variation in our device was explained based on the change in the contact-area formed between the multi-filament fiber electrodes and the PVDF-HFP/IL film. To demonstrate the applicability and scalability of the sensor device, a 3 × 3 pressure sensor array was fabricated. Due to its matrix-type array structure and capacitive sensing mechanism, multi-point detection was possible, and the different positions and the weights of the objects could be identified.

Recent Progress of Textile-Based Wearable Electronics: A Comprehensive Review of Materials, Devices, and Applications.

Wearable electronics are emerging as a platform for next-generation, human-friendly, electronic devices. A new class of devices with various functionality and amenability for the human body is essential. These new conceptual devices are likely to be a set of various functional devices such as displays, sensors, batteries, etc., which have quite different working conditions, on or in the human body. In these aspects, electronic textiles seem to be a highly suitable possibility, due to the unique characteristics of textiles such as being light weight and flexible and their inherent warmth and the property to conform. Therefore, e-textiles have evolved into fiber-based electronic apparel or body attachable types in order to foster significant industrialization of the key components with adaptable formats. Although the advances are noteworthy, their electrical performance and device features are still unsatisfactory for consumer level e-textile systems. To solve these issues, innovative structural and material designs, and novel processing technologies have been introduced into e-textile systems. Recently reported and significantly developed functional materials and devices are summarized, including their enhanced optoelectrical and mechanical properties. Furthermore, the remaining challenges are discussed, and effective strategies to facilitate the full realization of e-textile systems are suggested.

A Behavior-Learned Cross-Reactive Sensor Matrix for Intelligent Skin Perception.

Mimicking human skin sensation such as spontaneous multimodal perception and identification/discrimination of intermixed stimuli is severely hindered by the difficulty of efficient integration of complex cutaneous receptor-emulating circuitry and the lack of an appropriate protocol to discern the intermixed signals. Here, a highly stretchable cross-reactive sensor matrix is demonstrated, which can detect, classify, and discriminate various intermixed tactile and thermal stimuli using a machine-learning approach. Particularly, the multimodal perception ability is achieved by utilizing a learning algorithm based on the bag-of-words (BoW) model, where, by learning and recognizing the stimulus-dependent 2D output image patterns, the discrimination of each stimulus in various multimodal stimuli environments is possible. In addition, the single sensor device integrated in the cross-reactive sensor matrix exhibits multimodal detection of strain, flexion, pressure, and temperature. It is hoped that his proof-of-concept device with machine-learning-based approach will provide a versatile route to simplify the electronic skin systems with reduced architecture complexity and adaptability to various environments beyond the limitation of conventional "lock and key" approaches.

Highly Sensitive Textile Strain Sensors and Wireless User-Interface Devices Using All-Polymeric Conducting Fibers.

Emulation of diverse electronic devices on textile platform is considered as a promising approach for implementing wearable smart electronics. Of particular, the development of multifunctional polymeric fibers and their integration in common fabrics have been extensively researched for human friendly wearable platforms. Here we report a successful emulation of multifunctional body-motion sensors and user-interface (UI) devices in textile platform by using in situ polymerized poly(3,4-ethylenedioxythiophene) (PEDOT)-coated fibers. With the integration of PEDOT fibers in a fabric, via an optimization of the fiber pattern design, multifunctional textile sensors such as highly sensitive and reliable strain sensors (with maximum gauge factor of ∼1), body-motion monitoring sensors, touch sensors, and multilevel strain recognition UI devices were successfully emulated. We demonstrate the facile utilization of the textile-based multifunctional sensors and UI devices by implementing in a wireless system that is capable of expressing American Sign Language through predefined hand gestures.