A Pressure-Insensitive Self-Attachable Flexible Strain Sensor with Bioinspired Adhesive and Active CNT Layers

Flexible tactile sensors are required to maintain conformal contact with target objects and to differentiate different tactile stimuli such as strain and pressure to achieve high sensing performance. However, many existing tactile sensors do not have the ability to distinguish strain from pressure. Moreover, because they lack intrinsic adhesion capability, they require additional adhesive tapes for surface attachment. Herein, we present a self-attachable, pressure-insensitive strain sensor that can firmly adhere to target objects and selectively perceive tensile strain with high sensitivity. The proposed strain sensor is mainly composed of a bioinspired micropillar adhesive layer and a selectively coated active carbon nanotube (CNT) layer. We show that the bioinspired adhesive layer enables strong self-attachment of the sensor to diverse planar and nonplanar surfaces with a maximum adhesion strength of 257 kPa, while the thin film configuration of the patterned CNT layer enables high strain sensitivity (gauge factor (GF) of 2.26) and pressure insensitivity.

[1]  Kinam Kim,et al.  Highly stretchable electric circuits from a composite material of silver nanoparticles and elastomeric fibres. , 2012, Nature nanotechnology.

[2]  Seung Hwan Ko,et al.  Highly Stretchable and Transparent Supercapacitor by Ag-Au Core-Shell Nanowire Network with High Electrochemical Stability. , 2016, ACS applied materials & interfaces.

[3]  Nam Ki Min,et al.  Novel resistive-type humidity sensor based on multiwall carbon nanotube/polyimide composite films , 2010 .

[4]  Gang Liu,et al.  A skin-inspired tactile sensor for smart prosthetics , 2018, Science Robotics.

[5]  K. Suh,et al.  25th Anniversary Article: Scalable Multiscale Patterned Structures Inspired by Nature: the Role of Hierarchy , 2014, Advanced materials.

[6]  J. Xu,et al.  Highly Conductive Stretchable Electrodes Prepared by In Situ Reduction of Wavy Graphene Oxide Films Coated on Elastic Tapes , 2016 .

[7]  Yei Hwan Jung,et al.  Stretchable silicon nanoribbon electronics for skin prosthesis , 2014, Nature Communications.

[8]  Lili Wang,et al.  An ultra-sensitive and rapid response speed graphene pressure sensors for electronic skin and health monitoring , 2016 .

[9]  Ang Li,et al.  Aligned carbon nanotube sheet piezoresistive strain sensors , 2015 .

[10]  Inkyu Park,et al.  Low-temperature large-area fabrication of ZnO nanowires on flexible plastic substrates by solution-processible metal-seeded hydrothermal growth , 2020, Nano Convergence.

[11]  Hyung Jin Sung,et al.  Undulatory topographical waves for flow-induced foulant sweeping , 2019, Science Advances.

[12]  Huajian Gao,et al.  Shape insensitive optimal adhesion of nanoscale fibrillar structures. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[13]  Shinjae Kwon,et al.  Skin-conformal, soft material-enabled bioelectronic system with minimized motion artifacts for reliable health and performance monitoring of athletes. , 2020, Biosensors & bioelectronics.

[14]  Naveen Verma,et al.  Large-Area Resistive Strain Sensing Sheet for Structural Health Monitoring , 2020, Sensors.

[15]  Yu Pang,et al.  Flexible, Highly Sensitive, and Wearable Pressure and Strain Sensors with Graphene Porous Network Structure. , 2016, ACS applied materials & interfaces.

[16]  Min Zhao,et al.  A Dual‐Mode Wearable Sensor Based on Bacterial Cellulose Reinforced Hydrogels for Highly Sensitive Strain/Pressure Sensing , 2019, Advanced Electronic Materials.

[17]  Xiaofeng Zhou,et al.  Toward large-scale fabrication of triboelectric nanogenerator (TENG) with silk-fibroin patches film via spray-coating process , 2017 .

[18]  L. Guo,et al.  Simple hydrothermal synthesis of very-long and thin silver nanowires and their application in high quality transparent electrodes , 2016 .

[19]  Minsu Kang,et al.  Multifunctional Smart Skin Adhesive Patches for Advanced Health Care , 2018, Advanced healthcare materials.

[20]  Zhong Lin Wang,et al.  Taxel-Addressable Matrix of Vertical-Nanowire Piezotronic Transistors for Active and Adaptive Tactile Imaging , 2013, Science.

[21]  P. Lamberti,et al.  Piezoresistive properties of resin reinforced with carbon nanotubes for health-monitoring of aircraft primary structures , 2016 .

[22]  S. Sonkusale,et al.  Washable Smart Threads for Strain Sensing Fabrics , 2018, IEEE Sensors Journal.

[23]  Eduard Arzt,et al.  Gecko‐Inspired Surfaces: A Path to Strong and Reversible Dry Adhesives , 2010, Advanced materials.

[24]  Young Hee Lee,et al.  Effect of acid treatment on carbon nanotube-based flexible transparent conducting films. , 2007, Journal of the American Chemical Society.

[25]  B. Hu,et al.  Ultrasensitive cellular fluorocarbon piezoelectret pressure sensor for self-powered human physiological monitoring , 2017 .

[26]  J. Y. Sim,et al.  Microstructured Porous Pyramid-Based Ultrahigh Sensitive Pressure Sensor Insensitive to Strain and Temperature. , 2019, ACS applied materials & interfaces.

[27]  M. C. Tracey,et al.  Mechanical characterization of bulk Sylgard 184 for microfluidics and microengineering , 2014 .

[28]  M. Sitti,et al.  Bioinspired Composite Microfibers for Skin Adhesion and Signal Amplification of Wearable Sensors , 2017, Advanced materials.

[29]  R. Full,et al.  Adhesive force of a single gecko foot-hair , 2000, Nature.

[30]  Jianyong Ouyang,et al.  Wearable Stretchable Dry and Self‐Adhesive Strain Sensors with Conformal Contact to Skin for High‐Quality Motion Monitoring , 2020, Advanced Functional Materials.

[31]  Peyman Servati,et al.  Effects of inter-tube distance and alignment on tunnelling resistance and strain sensitivity of nanotube/polymer composite films , 2012, Nanotechnology.

[32]  James J. S. Norton,et al.  Materials and Optimized Designs for Human‐Machine Interfaces Via Epidermal Electronics , 2013, Advanced materials.

[33]  K Melzer,et al.  Back-gated spray-deposited carbon nanotube thin film transistors operated in electrolytic solutions: an assessment towards future biosensing applications. , 2013, Journal of materials chemistry. B.

[34]  Minsu Kang,et al.  Simple and Reliable Fabrication of Bioinspired Mushroom-Shaped Micropillars with Precisely Controlled Tip Geometries. , 2016, ACS applied materials & interfaces.

[35]  Xing Yi Ling,et al.  Hierarchical 3D SERS substrates fabricated by integrating photolithographic microstructures and self-assembly of silver nanoparticles. , 2014, Small.

[36]  Cunjiang Yu,et al.  Metal oxide semiconductor nanomembrane–based soft unnoticeable multifunctional electronics for wearable human-machine interfaces , 2019, Science Advances.

[37]  Hyung Wook Park,et al.  Hybrid Architectures of Heterogeneous Carbon Nanotube Composite Microstructures Enable Multiaxial Strain Perception with High Sensitivity and Ultrabroad Sensing Range. , 2018, Small.

[38]  Dae-Hyeong Kim,et al.  Multifunctional wearable devices for diagnosis and therapy of movement disorders. , 2014, Nature nanotechnology.

[39]  Deji Akinwande,et al.  Graphene Electronic Tattoo Sensors. , 2017, ACS nano.

[40]  Zhenan Bao,et al.  Rational Design of Capacitive Pressure Sensors Based on Pyramidal Microstructures for Specialized Monitoring of Biosignals , 2019, Advanced Functional Materials.

[41]  Sanggeun Lee,et al.  Conductive Hierarchical Hairy Fibers for Highly Sensitive, Stretchable, and Water‐Resistant Multimodal Gesture‐Distinguishable Sensor, VR Applications , 2019, Advanced Functional Materials.

[42]  K. Suh,et al.  A nontransferring dry adhesive with hierarchical polymer nanohairs , 2009, Proceedings of the National Academy of Sciences.

[43]  Metin Sitti,et al.  Biologically inspired polymer microfibers with spatulate tips as repeatable fibrillar adhesives , 2006 .

[44]  Ji-Beom Yoo,et al.  The production of a flexible electroluminescent device on polyethylene terephthalate films using transparent conducting carbon nanotube electrode , 2009 .

[45]  Ozgur Atalay,et al.  Weft-Knitted Strain Sensor for Monitoring Respiratory Rate and Its Electro-Mechanical Modeling , 2015, IEEE Sensors Journal.

[46]  Sangwoo Jin,et al.  Stretchable Array of Highly Sensitive Pressure Sensors Consisting of Polyaniline Nanofibers and Au-Coated Polydimethylsiloxane Micropillars. , 2015, ACS nano.

[47]  Bongkyun Jang,et al.  Graphene-Based Three-Dimensional Capacitive Touch Sensor for Wearable Electronics. , 2017, ACS nano.

[48]  Junyeob Yeo,et al.  Low‐Resistant Electrical and Robust Mechanical Contacts of Self‐Attachable Flexible Transparent Electrodes with Patternable Circuits , 2020, Advanced Functional Materials.

[49]  Jinliang Xie,et al.  An Antibacterial, Self-adhesive, Recyclable and Tough Conductive Composite Hydrogel for Ultrasensitive Strain Sensing. , 2020, ACS applied materials & interfaces.

[50]  Zhenan Bao,et al.  A chameleon-inspired stretchable electronic skin with interactive colour changing controlled by tactile sensing , 2015, Nature Communications.

[51]  Inkyu Park,et al.  Transparent, Flexible Strain Sensor Based on a Solution-Processed Carbon Nanotube Network. , 2017, ACS applied materials & interfaces.

[52]  Yu Song,et al.  Fingertip-inspired electronic skin based on triboelectric sliding sensing and porous piezoresistive pressure detection , 2017 .

[53]  P. Yang,et al.  Solution-Processed Copper/Reduced-Graphene-Oxide Core/Shell Nanowire Transparent Conductors. , 2016, ACS nano.

[54]  Jin-Woo Park,et al.  Wearable and Transparent Capacitive Strain Sensor with High Sensitivity Based on Patterned Ag Nanowire Networks. , 2017, ACS applied materials & interfaces.

[55]  Shu Yang,et al.  Orthogonal Control of Stability and Tunable Dry Adhesion by Tailoring the Shape of Tapered Nanopillar Arrays , 2015, Advanced materials.

[56]  Mehmet R. Yuce,et al.  Self-powered gold nanowire tattoo triboelectric sensors for soft wearable human-machine interface , 2020 .

[57]  Hyunkyu Park,et al.  Pressure Insensitive Strain Sensor with Facile Solution-Based Process for Tactile Sensing Applications. , 2018, ACS nano.

[58]  Ronan Sauleau,et al.  Multifunctional Flexible Sensor Based on Laser-Induced Graphene , 2019, Sensors.

[59]  Ning Hu,et al.  Piezoresistive Strain Sensors Made from Carbon Nanotubes Based Polymer Nanocomposites , 2011, Sensors.

[60]  Dae-Eun Kim,et al.  A highly flexible transparent conductive electrode based on nanomaterials , 2017 .

[61]  Z. Suo,et al.  A transparent bending-insensitive pressure sensor. , 2016, Nature nanotechnology.

[62]  Wei Gao,et al.  Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring , 2017, Advanced materials.

[63]  Min Han,et al.  An ultrahigh resolution pressure sensor based on percolative metal nanoparticle arrays , 2019, Nature Communications.

[64]  C. Grigoropoulos,et al.  Laser-induced direct graphene patterning and simultaneous transferring method for graphene sensor platform. , 2013, Small.

[65]  Hyun Kuk Kim,et al.  Nature-inspired rollable electronics , 2019, NPG Asia Materials.

[66]  Sanlin S. Robinson,et al.  Highly stretchable electroluminescent skin for optical signaling and tactile sensing , 2016, Science.

[67]  Insol Hwang,et al.  Wet‐Responsive, Reconfigurable, and Biocompatible Hydrogel Adhesive Films for Transfer Printing of Nanomembranes , 2018 .

[68]  J. Rho,et al.  Accordion-like plasmonic silver nanorod array exhibiting multiple electromagnetic responses , 2018, NPG Asia Materials.

[69]  Sung Youb Kim,et al.  Giant tunneling piezoresistance of composite elastomers with interlocked microdome arrays for ultrasensitive and multimodal electronic skins. , 2014, ACS nano.