A bionic tactile plastic hydrogel-based electronic skin constructed by a nerve-like nanonetwork combining stretchable, compliant, and self-healing properties

Abstract To completely mimic the tactile sensing of natural skin, flexible conductive hydrogels (CHs) have been assembled into bionic skin. However, most CHs cannot perfectly rebuild the feeling of human skin due to their highly linear structure. In addition, CHs are difficult to meet the super-stretchable, rapid self-healing properties at the same time. Here, we innovatively incorporated a proanthocyanins/reduced graphene oxide (PC/rGO) composite with a nerve-like nanonetwork into a glycerol-plasticized polyvinyl alcohol-borax (PVA-borax) hydrogel system to obtain a bionic tactile PC/rGO/PVA hydrogel-based electronic skin, which perfectly simulates the tactual sensation of human skin and integrates excellent stretchability (>5000%), compliance (1 mm), self-healing (3 s, 95.73%) ability for the first time. Due to its unique structure and mechanical properties, this electronic skin has remarkable wearable and strain-sensitive (GF = 14.14) properties, which can mimic and detect some real skin epidermis movements such as finger bending, facial expression changes, and throat vocalization. Interestingly, the hydrogel can also be used as an adhesive electrode for the accurate detection of electrocardiograph (ECG) and electromyography (EMG) signals. More importantly, this work provides a new route in mimicking the natural skin’s tactile ability through a hierarchical design of hydrogel networks.

[1]  Zhenan Bao,et al.  Pursuing prosthetic electronic skin. , 2016, Nature materials.

[2]  Peiyi Wu,et al.  Adaptable polyionic elastomers with multiple sensations and entropy-driven actuations for prosthetic skins and neuromuscular systems , 2019, Materials Horizons.

[3]  Yue Tan,et al.  Mussel-Inspired Nanocomposite Hydrogel-Based Electrodes with Reusable and Injectable Properties for Human Electrophysiological Signals Detection , 2019, ACS Sustainable Chemistry & Engineering.

[4]  Quankang Wang,et al.  A Bioinspired Mineral Hydrogel as a Self‐Healable, Mechanically Adaptable Ionic Skin for Highly Sensitive Pressure Sensing , 2017, Advanced materials.

[5]  Francisco Molina-Lopez,et al.  An integrated self-healable electronic skin system fabricated via dynamic reconstruction of a nanostructured conducting network , 2018, Nature Nanotechnology.

[6]  Xian Huang,et al.  Capacitive Epidermal Electronics for Electrically Safe, Long‐Term Electrophysiological Measurements , 2014, Advanced healthcare materials.

[7]  Boris Murmann,et al.  Skin electronics from scalable fabrication of an intrinsically stretchable transistor array , 2018, Nature.

[8]  Bo Wang,et al.  Mimicking Dynamic Adhesiveness and Strain-Stiffening Behavior of Biological Tissues in Tough and Self-Healable Cellulose Nanocomposite Hydrogels. , 2019, ACS applied materials & interfaces.

[9]  B. Sreedhar,et al.  Thermal, mechanical, and surface characterization of starch–poly(vinyl alcohol) blends and borax‐crosslinked films , 2005 .

[10]  Liqun Zhang,et al.  Wearable, Healable, and Adhesive Epidermal Sensors Assembled from Mussel‐Inspired Conductive Hybrid Hydrogel Framework , 2017 .

[11]  Guofa Cai,et al.  Extremely Stretchable Strain Sensors Based on Conductive Self‐Healing Dynamic Cross‐Links Hydrogels for Human‐Motion Detection , 2016, Advanced science.

[12]  Lina Zhang,et al.  Ultra‐Stretchable and Force‐Sensitive Hydrogels Reinforced with Chitosan Microspheres Embedded in Polymer Networks , 2016, Advanced materials.

[13]  Jianhua Zhang,et al.  Facile Access to Multisensitive and Self-Healing Hydrogels with Reversible and Dynamic Boronic Ester and Disulfide Linkages. , 2017, Biomacromolecules.

[14]  C. Zheng,et al.  Highly stretchable and fatigue resistant hydrogels with low Young's modulus as transparent and flexible strain sensors , 2018 .

[15]  Lih-Sheng Turng,et al.  Highly Stretchable and Biocompatible Strain Sensors Based on Mussel-Inspired Super-Adhesive Self-Healing Hydrogels for Human Motion Monitoring. , 2018, ACS applied materials & interfaces.

[16]  Zhigang Suo,et al.  Ionic skin , 2014, Advanced materials.

[17]  Y. Ni,et al.  Ultraflexible Self-Healing Guar Gum-Glycerol Hydrogel with Injectable, Antifreeze, and Strain-Sensitive Properties. , 2018, ACS biomaterials science & engineering.

[18]  Zhouyue Lei,et al.  A supramolecular biomimetic skin combining a wide spectrum of mechanical properties and multiple sensory capabilities , 2018, Nature Communications.

[19]  Qiu Jiang,et al.  MXenes stretch hydrogel sensor performance to new limits , 2018, Science Advances.

[20]  Menghao Wang,et al.  Transparent, Adhesive, and Conductive Hydrogel for Soft Bioelectronics Based on Light-Transmitting Polydopamine-Doped Polypyrrole Nanofibrils , 2018, Chemistry of Materials.

[21]  Zhouyue Lei,et al.  Zwitterionic Skins with a Wide Scope of Customizable Functionalities. , 2018, ACS nano.

[22]  Z. Suo,et al.  Hydrogel ionotronics , 2018, Nature Reviews Materials.

[23]  N. Tai,et al.  Green reduction of graphene oxide by Hibiscus sabdariffa L. to fabricate flexible graphene electrode , 2014 .

[24]  Pei Huang,et al.  A biomimetic multifunctional electronic hair sensor , 2019, Journal of Materials Chemistry A.

[25]  Qinglin Wu,et al.  Nanocellulose-Mediated Electroconductive Self-Healing Hydrogels with High Strength, Plasticity, Viscoelasticity, Stretchability, and Biocompatibility toward Multifunctional Applications. , 2018, ACS applied materials & interfaces.

[26]  Xuewen Wang,et al.  Silk‐Molded Flexible, Ultrasensitive, and Highly Stable Electronic Skin for Monitoring Human Physiological Signals , 2014, Advanced materials.

[27]  Zhong Lin Wang,et al.  Skin-inspired highly stretchable and conformable matrix networks for multifunctional sensing , 2018, Nature Communications.

[28]  Biao Huang,et al.  One-Pot Assembly of Microfibrillated Cellulose Reinforced PVA–Borax Hydrogels with Self-Healing and pH-Responsive Properties , 2017 .

[29]  Wen Cheng,et al.  Advanced electronic skin devices for healthcare applications. , 2019, Journal of materials chemistry. B.

[30]  Bo Wang,et al.  Mussel-Inspired Cellulose Nanocomposite Tough Hydrogels with Synergistic Self-Healing, Adhesive, and Strain-Sensitive Properties , 2018 .

[31]  Yan-Jun Liu,et al.  Ultrasensitive Wearable Soft Strain Sensors of Conductive, Self-healing, and Elastic Hydrogels with Synergistic "Soft and Hard" Hybrid Networks. , 2017, ACS applied materials & interfaces.

[32]  P. Messersmith,et al.  pH responsive self-healing hydrogels formed by boronate-catechol complexation. , 2011, Chemical communications.

[33]  Yong Zhu,et al.  Wearable silver nanowire dry electrodes for electrophysiological sensing , 2015 .

[34]  G. Shi,et al.  Self-assembled graphene hydrogel via a one-step hydrothermal process. , 2010, ACS nano.

[35]  Y. Ni,et al.  Ultrasoft Self-Healing Nanoparticle-Hydrogel Composites with Conductive and Magnetic Properties , 2018 .

[36]  Lih-Sheng Turng,et al.  Biocompatible, self-healing, highly stretchable polyacrylic acid/reduced graphene oxide nanocomposite hydrogel sensors via mussel-inspired chemistry , 2018, Carbon.

[37]  Lei Jiang,et al.  Hydrogel with Ultrafast Self-Healing Property Both in Air and Underwater. , 2018, ACS applied materials & interfaces.

[38]  Huipin Yuan,et al.  A Mussel-Inspired Conductive, Self-Adhesive, and Self-Healable Tough Hydrogel as Cell Stimulators and Implantable Bioelectronics. , 2017, Small.

[39]  Lihui Chen,et al.  Biocompatible, self-wrinkled, antifreezing and stretchable hydrogel-based wearable sensor with PEDOT:sulfonated lignin as conductive materials , 2019, Chemical Engineering Journal.

[40]  Florian J. Stadler,et al.  Rapid self-healing and triple stimuli responsiveness of a supramolecular polymer gel based on boron–catechol interactions in a novel water-soluble mussel-inspired copolymer , 2014 .

[41]  T. Someya,et al.  A Highly Sensitive Capacitive-type Strain Sensor Using Wrinkled Ultrathin Gold Films. , 2018, Nano letters (Print).

[42]  Pingping Wang,et al.  A compliant, self-adhesive and self-healing wearable hydrogel as epidermal strain sensor , 2018 .

[43]  Guanghui Gao,et al.  Ultra-stretchable wearable strain sensors based on skin-inspired adhesive, tough and conductive hydrogels , 2019, Chemical Engineering Journal.

[44]  Qinglin Wu,et al.  A self-healable and highly flexible supercapacitor integrated by dynamically cross-linked electro-conductive hydrogels based on nanocellulose-templated carbon nanotubes embedded in a viscoelastic polymer network , 2019, Carbon.

[45]  Zhenan Bao,et al.  A bioinspired flexible organic artificial afferent nerve , 2018, Science.

[46]  Benjamin C. K. Tee,et al.  25th Anniversary Article: The Evolution of Electronic Skin (E‐Skin): A Brief History, Design Considerations, and Recent Progress , 2013, Advanced materials.

[47]  Lihui Chen,et al.  An integrated transparent, UV-filtering organohydrogel sensor via molecular-level ion conductive channels , 2019, Journal of Materials Chemistry A.

[48]  Jingquan Han,et al.  High-water-content mouldable polyvinyl alcohol-borax hydrogels reinforced by well-dispersed cellulose nanoparticles: dynamic rheological properties and hydrogel formation mechanism. , 2014, Carbohydrate polymers.

[49]  Hua Li,et al.  A fast self-healing and conductive nanocomposite hydrogel as soft strain sensor , 2019, Colloids and Surfaces A: Physicochemical and Engineering Aspects.

[50]  Yeqiang Tan,et al.  Supramolecular nanofibrillar hydrogels as highly stretchable, elastic and sensitive ionic sensors , 2019, Materials Horizons.

[51]  Xuanhe Zhao,et al.  Hydrogel bioelectronics. , 2019, Chemical Society reviews.

[52]  Kyungtaek Min,et al.  Protein-Based Electronic Skin Akin to Biological Tissues. , 2018, ACS nano.