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Zhu J, Li J, Tong Y, Hu T, Chen Z, Xiao Y, Zhang S, Yang H, Gao M, Pan T, Cheng H, Lin Y. Recent progress in multifunctional, reconfigurable, integrated liquid metal-based stretchable sensors and standalone systems. Prog Mater Sci 2024; 142:101228. [PMID: 38745676 PMCID: PMC11090487 DOI: 10.1016/j.pmatsci.2023.101228] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Possessing a unique combination of properties that are traditionally contradictory in other natural or synthetical materials, Ga-based liquid metals (LMs) exhibit low mechanical stiffness and flowability like a liquid, with good electrical and thermal conductivity like metal, as well as good biocompatibility and room-temperature phase transformation. These remarkable properties have paved the way for the development of novel reconfigurable or stretchable electronics and devices. Despite these outstanding properties, the easy oxidation, high surface tension, and low rheological viscosity of LMs have presented formidable challenges in high-resolution patterning. To address this challenge, various surface modifications or additives have been employed to tailor the oxidation state, viscosity, and patterning capability of LMs. One effective approach for LM patterning is breaking down LMs into microparticles known as liquid metal particles (LMPs). This facilitates LM patterning using conventional techniques such as stencil, screening, or inkjet printing. Judiciously formulated photo-curable LMP inks or the introduction of an adhesive seed layer combined with a modified lift-off process further provide the micrometer-level LM patterns. Incorporating porous and adhesive substrates in LM-based electronics allows direct interfacing with the skin for robust and long-term monitoring of physiological signals. Combined with self-healing polymers in the form of substrates or composites, LM-based electronics can provide mechanical-robust devices to heal after damage for working in harsh environments. This review provides the latest advances in LM-based composites, fabrication methods, and their novel and unique applications in stretchable or reconfigurable sensors and resulting integrated systems. It is believed that the advancements in LM-based material preparation and high-resolution techniques have opened up opportunities for customized designs of LM-based stretchable sensors, as well as multifunctional, reconfigurable, highly integrated, and even standalone systems.
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Affiliation(s)
- Jia Zhu
- School of Material and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Jiaying Li
- School of Material and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yao Tong
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science, Suzhou 215011, PR China
| | - Taiqi Hu
- School of Electrical Engineering and Automation, Jiangxi University of Science and Technology, Ganzhou 341000, P. R. China
| | - Ziqi Chen
- School of Physical Sciences, University of Science and Technology of China, Hefei 230026, PR China
| | - Yang Xiao
- School of Material and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Senhao Zhang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science, Suzhou 215011, PR China
| | - Hongbo Yang
- Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Science, Suzhou 215011, PR China
| | - Min Gao
- School of Material and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Taisong Pan
- School of Material and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Huanyu Cheng
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yuan Lin
- School of Material and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China
- Medico-Engineering Cooperation on Applied Medicine Research Center, University of Electronics Science and Technology of China, Chengdu 610054, China
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Wu D, Wu S, Narongdej P, Duan S, Chen C, Yan Y, Liu Z, Hong W, Frenkel I, He X. Fast and Facile Liquid Metal Printing via Projection Lithography for Highly Stretchable Electronic Circuits. Adv Mater 2023:e2307632. [PMID: 38126914 DOI: 10.1002/adma.202307632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/19/2023] [Indexed: 12/23/2023]
Abstract
Soft electronic circuits are crucial for wearable electronics, biomedical technologies, and soft robotics, requiring soft conductive materials with high conductivity, high strain limit, and stable electrical performance under deformation. Liquid metals (LMs) have become attractive candidates with high conductivity and fluidic compliance, while effective manufacturing methods are demanded. Digital light processing (DLP)-based projection lithography is a high-resolution and high-throughput printing technique for primarily polymers and some metals. If LMs can be printed with DLP as well, the entire soft devices can be fabricated by one printer in a streamlined and highly efficient process. Herein, fast and facile DLP-based LM printing is achieved. Simply with 5-10 s of patterned ultraviolet (UV)-light exposure, a highly conductive and stretchable pattern can be printed using a photo-crosslinkable LM particle ink. The printed eutectic gallium indium traces feature high resolution (≈20 µm), conductivity (3 × 106 S m-1 ), stretchability (≈2500%), and excellent stability (consistent performance at different deformation). Various patterns are printed in diverse material systems for broad applications including stretchable displays, epidermal strain sensors, heaters, humidity sensors, conformal electrodes for electrography, and multi-layer actuators. The facile and scalable process, excellent performance, and diverse applications ensure its broad impact on soft electronic manufacturing.
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Affiliation(s)
- Dong Wu
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Shuwang Wu
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Poom Narongdej
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Sidi Duan
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Chi Chen
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Yichen Yan
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Zixiao Liu
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Wen Hong
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Imri Frenkel
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
| | - Ximin He
- Department of Materials Science and Engineering, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
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Hu F, Huang Z, Luo C, Yue K. High-sensitivity and ultralow-hysteresis fluorine-rich ionogel strain sensors for multi-environment contact and contactless sensing. Mater Horiz 2023; 10:5907-5919. [PMID: 37870851 DOI: 10.1039/d3mh01138k] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Information transduction via soft strain sensors under harsh conditions such as marine, oily liquid, vacuum, and extreme temperatures without excess encapsulation facilitates modern scientific and military exploration. However, most reported soft strain sensors struggle to meet these requirements, especially in complex environments. Herein, a class of fluorine-rich ionogels with tunable ultimate strain, high conductivity, and multi-environment tolerance are designed. Abundant ion-dipole and dipole-dipole interactions lead to excellent miscibility between the hydrophobic ionic liquid and the fluorinated polyacrylate matrix, as well as adhesion to diverse substrates in amphibious environments. The ionogel-based sensors, even in encapsulation-free form, exhibit stable operation with a negligible hysteresis (as low as 0.119%) and high sensitivity (gauge factor of up to 6.54) under amphibious conditions. Multi-environment sensing instances in contact and even contactless forms are also demonstrated. This study opens the door for the artificial syntheses of multi-environment tolerance ionic skins with robust sensing applications in soft electronics and robotics.
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Affiliation(s)
- Faqi Hu
- South China Advanced Institute for Soft Matter Science and Technology and School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Zhenkai Huang
- School of Materials Science and Hydrogen Energy, Foshan University, Foshan 528000, China
| | - Chuan Luo
- South China Advanced Institute for Soft Matter Science and Technology and School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
| | - Kan Yue
- South China Advanced Institute for Soft Matter Science and Technology and School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
- Jiangsu Key Laboratory of Advanced Functional Polymers Design and Application, Soochow University, Suzhou 215000, China
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Liu Y, Zhang C, Chen Y, Yin R, He P, Zhao W. Rational Design of Conductive Pathways in Flexible Tactile Sensors via Indirect 3D-Printing of Liquid Metal for High-Precision Monitoring and Recognition. ACS Appl Mater Interfaces 2023; 15:38572-38580. [PMID: 37526636 DOI: 10.1021/acsami.3c07237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Highly sensitive and conformal sensors are essential for the implementation of human-machine interfaces, health monitoring, and rehabilitation prostheses. The proper adjustment of conductive pathways in the sensing materials is essential for their sensitive transduction of mechanical stimuli into electrical signals. However, the rational, precise, and wide-range control of electrical networks within traditional conductive composites is difficult due to the randomly distributed fillers. Herein, we adopt an indirect 3D-printing method to fabricate pressure sensors with various microchannels for liquid metal (LM) to form consistent and tunable conductive pathways. LM is highly conductive, fluidic, and incompressible at ambient conditions, which guarantees the reliable regulation and function of our pressure sensor. Additive manufacturing provides a facile way to construct complicated microchannels with different lengths, different orientations, cross-sectional sizes, depth-width ratios, and shapes, which can effectively modulate the sensitivity and the sensing range. Under the optimized structural configurations, our sensor achieves a high sensitivity of 1.139 kPa-1, a detection range of 0-68 kPa (loading process), and stability of over 5000 cycles, whose sensing performance is better than most microchannel-filled LM sensors. It can achieve high-accuracy monitoring of pulse, speaking and gestures, and exhibit a full recognition of objects under the assistance of machine learning. This work can provide new ideas on the design of conductive pathways in flexible electronics and expand the application of recyclable LM in human-machine interfaces.
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Affiliation(s)
- Yaming Liu
- Sauvage Laboratory for Smart Materials, The School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001, People's Republic of China
| | - Chen Zhang
- Sauvage Laboratory for Smart Materials, The School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
| | - Youyou Chen
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001, People's Republic of China
- Laboratory for Smart Materials, The School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
| | - Rui Yin
- Sauvage Laboratory for Smart Materials, The School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
| | - Peng He
- State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001, People's Republic of China
| | - Weiwei Zhao
- Sauvage Laboratory for Smart Materials, The School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- Shenzhen Key Laboratory of Flexible Printed Electronics Technology, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, People's Republic of China
- State Key Laboratory of Advanced Welding & Joining, Harbin Institute of Technology, Harbin 150001, People's Republic of China
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Abstract
The application of three-dimensional common electronics that can be directly pasted on arbitrary surfaces in the fields of human health monitoring, intelligent robots and wearable electronic devices has aroused people's interest, especially in achieving stable adhesion of electronic devices on biological dynamic three-dimensional interfaces and high-quality signal acquisition. In recent years, liquid metal (LM) materials have been widely used in the manufacture of flexible sensors and wearable electronic devices because of their excellent tensile properties and electrical conductivity at room temperature. In addition, LM has good biocompatibility and can be used in a variety of biomedical applications. Here, the recent development of LM flexible electronic printing methods for the fabrication of three-dimensional conformal electronic devices on the surface of human tissue is discussed. These printing methods attach LM to the deformable substrate in the form of bulk or micro-nano particles, so that electronic devices can adapt to the deformation of human tissue and other three-dimensional surfaces, and maintain stable electrical properties. Representative examples of applications such as self-healing devices, degradable devices, flexible hybrid electronic devices, variable stiffness devices and multi-layer large area circuits are reviewed. The current challenges and prospects for further development are also discussed.
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Kim M, Lim H, Ko SH. Liquid Metal Patterning and Unique Properties for Next-Generation Soft Electronics. Adv Sci (Weinh) 2023; 10:e2205795. [PMID: 36642850 PMCID: PMC9951389 DOI: 10.1002/advs.202205795] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/27/2022] [Indexed: 05/28/2023]
Abstract
Room-temperature liquid metal (LM)-based electronics is expected to bring advancements in future soft electronics owing to its conductivity, conformability, stretchability, and biocompatibility. However, various difficulties arise when patterning LM because of its rheological features such as fluidity and surface tension. Numerous attempts are made to overcome these difficulties, resulting in various LM-patterning methods. An appropriate choice of patterning method based on comprehensive understanding is necessary to fully utilize the unique properties. Therefore, the authors aim to provide thorough knowledge about patterning methods and unique properties for LM-based future soft electronics. First, essential considerations for LM-patterning are investigated. Then, LM-patterning methods-serial-patterning, parallel-patterning, intermetallic bond-assisted patterning, and molding/microfluidic injection-are categorized and investigated. Finally, perspectives on LM-based soft electronics with unique properties are provided. They include outstanding features of LM such as conformability, biocompatibility, permeability, restorability, and recyclability. Also, they include perspectives on future LM-based soft electronics in various areas such as radio frequency electronics, soft robots, and heterogeneous catalyst. LM-based soft devices are expected to permeate the daily lives if patterning methods and the aforementioned features are analyzed and utilized.
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Affiliation(s)
- Minwoo Kim
- Applied Nano and Thermal Science LabDepartment of Mechanical EngineeringSeoul National University1 Gwanak‐ro, Gwanak‐guSeoul08826South Korea
| | - Hyungjun Lim
- Applied Nano and Thermal Science LabDepartment of Mechanical EngineeringSeoul National University1 Gwanak‐ro, Gwanak‐guSeoul08826South Korea
- Department of Mechanical EngineeringPohang University of Science and Technology77 Chungam‐ro, Nam‐guPohang37673South Korea
| | - Seung Hwan Ko
- Applied Nano and Thermal Science LabDepartment of Mechanical EngineeringSeoul National University1 Gwanak‐ro, Gwanak‐guSeoul08826South Korea
- Institute of Advanced Machinery and Design/Institute of Engineering ResearchSeoul National University1 Gwanak‐ro, Gwanak‐guSeoul08826South Korea
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Cao J, Li X, Liu Y, Zhu G, Li RW. Liquid Metal-Based Electronics for On-Skin Healthcare. Biosensors (Basel) 2023; 13:bios13010084. [PMID: 36671919 PMCID: PMC9856137 DOI: 10.3390/bios13010084] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 05/28/2023]
Abstract
Wearable devices are receiving growing interest in modern technologies for realizing multiple on-skin purposes, including flexible display, flexible e-textiles, and, most importantly, flexible epidermal healthcare. A 'BEER' requirement, i.e., biocompatibility, electrical elasticity, and robustness, is first proposed here for all the on-skin healthcare electronics for epidermal applications. This requirement would guide the designing of the next-generation on-skin healthcare electronics. For conventional stretchable electronics, the rigid conductive materials, e.g., gold nanoparticles and silver nanofibers, would suffer from an easy-to-fail interface with elastic substrates due to a Young's modulus mismatch. Liquid metal (LM) with high conductivity and stretchability has emerged as a promising solution for robust stretchable epidermal electronics. In addition, the fundamental physical, chemical, and biocompatible properties of LM are illustrated. Furthermore, the fabrication strategies of LM are outlined for pure LM, LM composites, and LM circuits based on the surface tension control. Five dominant epidermal healthcare applications of LM are illustrated, including electrodes, interconnectors, mechanical sensors, thermal management, and biomedical and sustainable applications. Finally, the key challenges and perspectives of LM are identified for the future research vision.
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Affiliation(s)
- Jinwei Cao
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
| | - Xin Li
- School of Integrated Circuits and Beijing National Research Centre for Information Science and Technology (BNRist), Tsinghua University, Beijing 100084, China
| | - Yiwei Liu
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
| | - Guang Zhu
- Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham Ningbo China, Ningbo 315100, China
| | - Run-Wei Li
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
- Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China
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Yang B, Yang Z, Tang L. Recent progress in fiber-based soft electronics enabled by liquid metal. Front Bioeng Biotechnol 2023; 11:1178995. [PMID: 37187888 PMCID: PMC10175636 DOI: 10.3389/fbioe.2023.1178995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/20/2023] [Indexed: 05/17/2023] Open
Abstract
Soft electronics can seamlessly integrate with the human skin which will greatly improve the quality of life in the fields of healthcare monitoring, disease treatment, virtual reality, and human-machine interfaces. Currently, the stretchability of most soft electronics is achieved by incorporating stretchable conductors with elastic substrates. Among stretchable conductors, liquid metals stand out for their metal-grade conductivity, liquid-grade deformability, and relatively low cost. However, the elastic substrates usually composed of silicone rubber, polyurethane, and hydrogels have poor air permeability, and long-term exposure can cause skin redness and irritation. The substrates composed of fibers usually have excellent air permeability due to their high porosity, making them ideal substrates for soft electronics in long-term applications. Fibers can be woven directly into various shapes, or formed into various shapes on the mold by spinning techniques such as electrospinning. Here, we provide an overview of fiber-based soft electronics enabled by liquid metals. An introduction to the spinning technology is provided. Typical applications and patterning strategies of liquid metal are presented. We review the latest progress in the design and fabrication of representative liquid metal fibers and their application in soft electronics such as conductors, sensors, and energy harvesting. Finally, we discuss the challenges of fiber-based soft electronics and provide an outlook on future prospects.
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Affiliation(s)
- Bowen Yang
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, School of Biomedical Engineering, Capital Medical University, Beijing, China
| | - Zihan Yang
- Fashion Accessory Art and Engineering College, Beijing Institute of Fashion Technology, Beijing, China
- *Correspondence: Zihan Yang, ; Lixue Tang,
| | - Lixue Tang
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, School of Biomedical Engineering, Capital Medical University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Capital Medical University, Beijing, China
- *Correspondence: Zihan Yang, ; Lixue Tang,
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