Flexible and Highly Sensitive Strain Sensors Fabricated by Pencil Drawn for Wearable Monitor

Abstract

1wileyonlinelibrary.com schemes, the fl exible functional sensors are competitive and attractive candidates for promoting the advancement of sensing system. Recently, for the achievement of sensing devices, the printing technique has attracted widespread attention and been pursued to deposit various materials, like carbon materials, [ 13,23,24 ] polymers, [ 25,26 ] metals, [ 12,27 ] and semiconductors, [ 28,29 ] because the process is low energy consumption while maintaining the unique properties of the materials. By this way, the fl exible devices can be cheaper and easily produced.Graphite, one of carbon allotropes, has been increasing wide and keen interests of researchers, due to a wonder material of graphene. [ 9,[30][31][32] Pencil, a day-to-day material, is a nanocomposite of graphite and intercalated clay. [33][34][35] Being layered or pelleted, pencil lead can be exfoliated by using a gentle force. The drawing process can easily deposit graphite onto a rough paper, which contains massive amounts of cellulose fi bers and offer a naturally porous structure. [ 13,36 ] Pencil-trace drawn on printing papers is perhaps the simplest and easiest way of constructing graphite-based devices. The pen-on-paper (PoP) approach, a basic printing technique, offers a unique method to fabricate fl exible devices, such as strain sensors, [ 35 ] biosensors, [ 19,37 ] microfl uidic chips, [ 38 ] electronic devices, [ 34,39 ] photoconductive sensors, [ 29,40 ] and energy-storage devices. [ 33,41,42 ] Most of these devices have a response to force-induce changes in capacitance [ 33 ] and resistivity. [ 35 ] The microcontact-reversible sensing can effectively translate the microstructural deformations into electrical signals on active fl exible substrates. [ 6,9,43,44 ] As the potential to make fl exible, lightweight, portable, biocompatible, economical, and environment-friendly products, the PoP approach has an important role on the breakthroughs toward fl exible and wearable sensing devices.Herein, we demonstrate that the application of PoP approach can be expanded further to crucial fl exible sensing devices. We evaluated the repeatability of bending-unbending and the robustness of the strain sensors applied by loading. The strain sensors have a rapid respond to microdeformation changes and can be used to monitor various structural change and even human motion through facilitative and effective installing designs. Typically, the microdeformation of <0.13% strain can be detected. Compared with the recently reported fl exible sensing devices, the strain sensors behave signifi cant Flexible and Highly Sensitive Strain Sensors Fabricated by Pencil Drawn for Wearable MonitorXinqin Liao , Qingliang Liao , Xiaoqin Yan , Qijie Liang , Haonan Si , Minghua Li , Hualin Wu , Shiyao Cao , and Yue Zhang * Functional electrical devices have promising potentials in structural health monitoring system, human-friendly wearable interactive system, smart robotics, and even future multifunctional intelligent room. Here, a low-cost fabrication s...

A Highly Stretchable ZnO@Fiber‐Based Multifunctional Nanosensor for Strain/Temperature/UV Detection

“…Second, the PU fi bers were heated at low temperature of 50 °C within 5 min. Subsequently, the pretreated PU fi bers can be immersed into an aqueous solution of zinc acetate dihydrate [Zn(CH 3 COO) 2 •2H 2 O] (0.01 M ). Then, an aqueous solution of potassium hydroxide (KOH, 0.03 M ) was dropped into the reaction solution with stirring and ultrasonic processing for 15 min.…”

“…[ 1 ] Much effort has been devoted to enhancing sensing properties for better signal detection, including but not limited to pressure/strain, [2][3][4][5][6] photo, [7][8][9] and temperature. [ 10,11 ] In general, each of these sensors is utilized to detect a single signal.…”

High-throughput shadow mask printing of passive electrical components on paper by supersonic cluster beam deposition

“…7 The printing of passive circuital elements on plain paper, such as resistors and capacitors, is less demanding; however, chip-on-flex and soft robotics technologies require the production of large batches of components to be subsequently assembled in 2D or 3D configurations, with different electrical and geometrical characteristics. 1,6,10 Among different approaches, ink-jet printing is considered a technique of choice for the printing of simple electronic circuits on paper with the use of conductive inks and for the fabrication of passive and active elements. 11 The use of ink-jet printing is limited by the availability of conducting inks with suitable properties (surface tension, viscosity) able to match the roughness, porosity, and wettability of the paper substrates; moreover, the post-printing ink drying process is difficult to control, and it can lead to unwanted variations of the electrical properties of the components.…”

Tailoring force sensitivity and selectivity by microstructure engineering of multidirectional electronic skins

“…Recently, a large number of electronic skins with capabilities of detecting physical/chemical stimuli have been reported for applications in robotics, wearable electronics, and healthcare monitoring devices [1][2][3][4][5][6][7][8] . Owing to their wearable or body-attachable features, many types of electronic skins (e-skins) have been actively utilized as innovative tools for monitoring radial and carotid blood pressure 1,2 , and electrophysiological signals 3,4 and for oximetry 5 , as well as drug delivery 6 .…”