Fiber-based structures are highly desirable for wearable electronics that are expected to be light-weight, long-lasting, flexible, and conformable Many fibrous structures have been manufactured by well-established lost-effective textile processing technologies, normally at ambient conditions The advancement of nanotechnology has made it feasible to build electronic devices directly on the surface or inside of single fibers, which have typical thickness of several to tens microns However, imparting electronic functions to porous, highly deformable and three-dimensional fiber assemblies and maintaining them during wear represent great challenges from both views of fundamental understanding and practical implementation This article attempts to critically review the current state-of-arts with respect to materials, fabrication techniques, and structural design of devices as well as applications of the fiber-based wearable electronic products In addition, this review elaborates the performance requirements of the fiber-based wearable electronic products, especially regarding the correlation among materials, fiber/textile structures and electronic as well as mechanical functionalities of fiber-based electronic devices Finally, discussions will be presented regarding to limitations of current materials, fabrication techniques, devices concerning manufacturability and performance as well as scientific understanding that must be improved prior to their wide adoption

Fiber‐Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications

Electronic Textiles (e-textiles) are fabrics that feature electronics and interconnections woven into them, presenting physical flexibility and typical size that cannot be achieved with other existing electronic manufacturing techniques. Components and interconnections are intrinsic to the fabric and thus are less visible and not susceptible of becoming tangled or snagged by surrounding objects. E-textiles can also more easily adapt to fast changes in the computational and sensing requirements of any specific application, this one representing a useful feature for power management and context awareness. The vision behind wearable computing foresees future electronic systems to be an integral part of our everyday outfits. Such electronic devices have to meet special requirements concerning wearability. Wearable systems will be characterized by their ability to automatically recognize the activity and the behavioral status of their own user as well as of the situation around her/him, and to use this information to adjust the systems' configuration and functionality. This review focuses on recent advances in the field of Smart Textiles and pays particular attention to the materials and their manufacturing process. Each technique shows advantages and disadvantages and our aim is to highlight a possible trade-off between flexibility, ergonomics, low power consumption, integration and eventually autonomy.

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Wearable Electronics and Smart Textiles: A Critical Review

The process of acquiring the energy surround- ing a system and converting it into usable electrical energy is termed power harvesting. In the last few years, there has been a surge of research in the area of power harvesting. This increase in research has been brought on by the mod- ern advances in wireless technology and low-power electron- ics such as microelectromechanical systems. The advances have allowed numerous doors to open for power harvesting systems in practical real-world applications. The use of pie- zoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramat- ic rise in use for power harvesting. Piezoelectric materials have a crystalline structure that provides them with the ability to transform mechanical strain energy into electrical charge and, vice versa, to convert an applied electrical potential into mechanical strain. This property provides these materials with the ability to absorb mechanical energy from their surround- ings, usually ambient vibration, and transform it into electrical energy that can be used to power other devices. While piezo- electric materials are the major method of harvesting energy, other methods do exist; for example, one of the conventional methods is the use of electromagnetic devices. In this paper we discuss the research that has been performed in the area of power harvesting and the future goals that must be achieved for power harvesting systems to find their way into everyday use. and replacement of the battery can become a tedious task. In the case of wireless sensors, these devices can be placed in very remote locations such as structural sensors on a bridge or global positioning system (GPS) tracking devices on ani- mals in the wild. When the battery is extinguished of all its power, the sensor must be retrieved and the battery re- placed. Because of the remote placement of these devices, obtaining the sensor simply to replace the battery can be- come a very expensive task or even impossible. For in- stance, in civil infrastructure applications it is often desirable to embed the sensor, making battery replacement unfeasible. If ambient energy in the surrounding medium could be ob- tained, then it could be used to replace or charge the battery. One method is to use piezoelectric materials to obtain ener- gy lost due to vibrations of the host structure. This captured energy could then be used to prolong the life of the power supply or in the ideal case provide endless energy for the electronic devices lifespan. For these reasons, the amount of research devoted to power harvesting has been rapidly in- creasing. In this paper we review and detail some of the top- ics in power harvesting that have been receiving the most research, including energy harvesting from mechanical vi- bration, biological systems, and the effects of power har- vesting on the vibration of a structure.

A Review of Power Harvesting from Vibration using

The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, there has been a surge of research in the area of power harvesting. This increase in research has been brought on by the modern advances in wireless technology and low-power electronics such as microelectromechanical systems. The advances have allowed numerous doors to open for power harvesting systems in practical real-world applications. The use of piezoelectric materials to capitalize on the ambient vibrations surrounding a system is one method that has seen a dramatic rise in use for power harvesting. Piezoelectric materials have a crystalline structure that provides them with the ability to transform mechanical strain energy into electrical charge and, vice versa, to convert an applied electrical potential into mechanical strain. This property provides these materials with the ability to absorb mechanical energy from their surroundings, usually ambient vibration, and transform it into electrical energy that can be used to power other devices. While piezoelectric materials are the major method of harvesting energy, other methods do exist; for example, one of the conventional methods is the use of electromagnetic devices. In this paper we discuss the research that has been performed in the area of power harvesting, and the future goals that must be achieved for power harvesting systems to find their way into everyday use.

A Review of Power Harvesting from Vibration using Piezoelectric Materials

The present invention teaches a variety of methods and systems for providing computer/human interfaces. According to one method, the user interfaces with an electronic device such as a computer system by engaging a sensor with desired regions of an encoded physical medium. The encoded physical medium is preferably chosen to provide intuitive meaning to the user, and is thus an improved metaphor for interfacing with the computer system. Suitable examples of the encoded physical medium include a data-linked book, magazine, globe, or article of clothing. Some or all of the selected regions have had certain information encoded therein, information suitable for interfacing and controlling the computer system. When the user engages the sensor with a region having certain encoded information, the certain encoded information is interpreted and an appropriate action taken. For example, the sensor or the computer system may provide suitable feedback to the user. The encoded physical medium may have text and/or graphic illustrations that draw the user in or provide meaningful clues or instructions perhaps related to the encoded information. The sensor may have at least one identification number (ID) providing information such as user identity, sensor type, access type, or language type. The sensor can transmit the certain decoded information together with the at least one ID to the computer system.

Methods and systems for providing human/computer interfaces

Highly durable, flexible, and even washable multilayer electronic circuitry can be constructed on textile substrates, using conductive yarns and suitably packaged components. In this paper we describe the development of e-broidery (electronic embroidery, i.e., the patterning of conductive textiles by numerically controlled sewing or weaving processes) as a means of creating computationally active textiles. We compare textiles to existing flexible circuit substrates with regard to durability, conformability, and wearability. We also report on: some unique applications enabled by our work; the construction of sensors and user interface elements in textiles; and a complete process for creating flexible multilayer circuits on fabric substrates. This process maintains close compatibility with existing electronic components and design tools, while optimizing design techniques and component packages for use in textiles.

E-broidery: design and fabrication of textile-based computing

This paper presents a system for interacting with digital information, called Triangles. The Triangles system is a physical/digital construction kit, which allows users to use two hands to grasp and manipulate complex digital information. The kit consists of a set of identical flat, plastic triangles, each with a microprocessor inside and magnetic edge connectors. The connectors enable the Triangles to be physically connected to each other and provide tactile feedback of these connections. The connectors also pass electricity, allowing the Triangles to communicate digital information to each other and to a desktop computer. When the pieces contact one another, specific connection information is sent back to a computer that keeps track of the configuration of the system. Specific two and three-dimensional configurations of the pieces can trigger application events. The Triangles system provides a physical embodiment of digital information topography. The individual tiles have a simple geometric form which does not inherit the semantics of everyday physical objects. Their shape, size, and connectors encourage rapid rearrangement and exploration of groups of Triangles. The infinitely reconfigurable 2D and 3D topographies of the Triangles system create a new language for tangible interface.

Triangles: tangible interface for manipulation and exploration of digital information topography

Fabrics are used as integral elements of electrical circuitry—to facilitate control over the operation of external components connected thereto, to serve as substrates onto which electrical components are connected, or as the electrical components themselves. In one aspect, selective, anisotropic electrical conductivity is achieved using conductive fibers running along one weave direction and non-conductive fibers running along the opposite direction. The conductive fibers, which may be continuous or arranged in lanes, serve as electrical conduits capable of carrying data signals and/or power, and may be connected, for example, to electrical components soldered directly onto the fabric. In a second aspect, passive electrical components are integrated directly textiles using threads having selected electrical properties.

Electrically active textiles and articles made therefrom

Wearable computers can now merge seamlessly into ordinary clothing. Using various conductive textiles, data and power distribution as well as sensing circuitry can be incorporated directly into wash-and-wear clothing. This paper describes some of the techniques used to build circuits from commercially available fabrics, yarns, fasteners, and components.

Smart fabric, or "wearable clothing"

Apparatus for continuous sensing of hand and arm gestures comprises hand-held means for continuously sensing at least tempo and emphasis. These sensed parameters are represented quantitatively, and transduced by appropriate circuitry into electrical signals indicative of the parameter quantities. The signals may be used to control the performance of a musical composition (or the evolution of some other dynamic system), or may instead convey information. The signals may, for example, be provided to an interpreter that dynamically infers control commands from the gestures on a real-time basis in accordance with the generally accepted canon of musical conducting, directing the controlled system in accordance therewith. The invention may also sense one or more additional conducting parameters such as the speed and/or velocity, direction (i.e., trajectory) in three dimensions, absolute three-dimensional position, the "size" of a gesture in terms of the spatial distance between successive beats, and the "placement" of a beat pattern in space.

Maggie Orth

Papers

E-broidery: design and fabrication of textile-based computing

Triangles: tangible interface for manipulation and exploration of digital information topography

Electrically active textiles and articles made therefrom

Smart fabric, or "wearable clothing"

Apparatus for controlling continuous behavior through hand and arm gestures