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Jeon J, Park JW. Stretchable Electrodes for Interconnects in Soft Electronics. NANO LETTERS 2024. [PMID: 39041723 DOI: 10.1021/acs.nanolett.4c02107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Soft electronics have significantly enhanced user convenience and data accuracy in wearable devices, implantable devices, and human-machine interfaces. However, a persistent challenge in their development has been the disconnection between the rigid and soft components of devices due to the substantial difference in modulus and stretchability. To address this issue, establishing a durable and flexible connection that smoothly links components of varying stiffness to signal-capturing sections with a lower stiffness is essential. In this study, we developed a novel stretchable interconnect that strongly adheres to various materials, facilitating electrical connections effortlessly by applying minimal finger pressure. Capable of stretching up to 1000% while maintaining electrical integrity, this interconnect proves its applicability across multiple domains, including electrocardiogram (ECG), electromyography (EMG), and stretchable light-emitting diode (LED) circuits. Its versatility is further demonstrated through its compatibility with various manufacturing techniques such as 3D printing, painting, and spin coating, highlighting its adaptability in soft electronics.
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Affiliation(s)
- Jiwan Jeon
- Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jin-Woo Park
- Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
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Nam S, Cha GD, Sunwoo SH, Jeong JH, Kang H, Park OK, Lee KY, Oh S, Hyeon T, Choi SH, Lee SP, Kim DH. Needle-Like Multifunctional Biphasic Microfiber for Minimally Invasive Implantable Bioelectronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2404101. [PMID: 38842504 DOI: 10.1002/adma.202404101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 05/14/2024] [Indexed: 06/07/2024]
Abstract
Implantable bioelectronics has attracted significant attention in electroceuticals and clinical medicine for precise diagnosis and efficient treatment of target diseases. However, conventional rigid implantable devices face challenges such as poor tissue-device interface and unavoidable tissue damage during surgical implantation. Despite continuous efforts to utilize various soft materials to address such issues, their practical applications remain limited. Here, a needle-like stretchable microfiber composed of a phase-convertible liquid metal (LM) core and a multifunctional nanocomposite shell for minimally invasive soft bioelectronics is reported. The sharp tapered microfiber can be stiffened by freezing akin to a conventional needle to penetrate soft tissue with minimal incision. Once implanted in vivo where the LM melts, unlike conventional stiff needles, it regains soft mechanical properties, which facilitate a seamless tissue-device interface. The nanocomposite incorporating with functional nanomaterials exhibits both low impedance and the ability to detect physiological pH, providing biosensing and stimulation capabilities. The fluidic LM embedded in the nanocomposite shell enables high stretchability and strain-insensitive electrical properties. This multifunctional biphasic microfiber conforms to the surfaces of the stomach, muscle, and heart, offering a promising approach for electrophysiological recording, pH sensing, electrical stimulation, and radiofrequency ablation in vivo.
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Affiliation(s)
- Seonghyeon Nam
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Gi Doo Cha
- Department of Systems Biotechnology, Chung-Ang University, Ansung, 17546, Republic of Korea
| | - Sung-Hyuk Sunwoo
- Department of Chemical Engineering, Kumoh National Institute of Technology, Gumi, 39177, Republic of Korea
| | - Jae Hwan Jeong
- Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Hyejeong Kang
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
| | - Ok Kyu Park
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Radiology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Kyeong-Yeon Lee
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Seil Oh
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, 03080, Republic of Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Seung Hong Choi
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Radiology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Seung-Pyo Lee
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, 03080, Republic of Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
| | - Dae-Hyeong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
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Han SI, Sunwoo SH, Park CS, Lee SP, Hyeon T, Kim DH. Next-Generation Cardiac Interfacing Technologies Using Nanomaterial-Based Soft Bioelectronics. ACS NANO 2024; 18:12025-12048. [PMID: 38706306 DOI: 10.1021/acsnano.4c02171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Cardiac interfacing devices are essential components for the management of cardiovascular diseases, particularly in terms of electrophysiological monitoring and implementation of therapies. However, conventional cardiac devices are typically composed of rigid and bulky materials and thus pose significant challenges for effective long-term interfacing with the curvilinear surface of a dynamically beating heart. In this regard, the recent development of intrinsically soft bioelectronic devices using nanocomposites, which are fabricated by blending conductive nanofillers in polymeric and elastomeric matrices, has shown great promise. The intrinsically soft bioelectronics not only endure the dynamic beating motion of the heart and maintain stable performance but also enable conformal, reliable, and large-area interfacing with the target cardiac tissue, allowing for high-quality electrophysiological mapping, feedback electrical stimulations, and even mechanical assistance. Here, we explore next-generation cardiac interfacing strategies based on soft bioelectronic devices that utilize elastic conductive nanocomposites. We first discuss the conventional cardiac devices used to manage cardiovascular diseases and explain their undesired limitations. Then, we introduce intrinsically soft polymeric materials and mechanical restraint devices utilizing soft polymeric materials. After the discussion of the fabrication and functionalization of conductive nanomaterials, the introduction of intrinsically soft bioelectronics using nanocomposites and their application to cardiac monitoring and feedback therapy follow. Finally, comments on the future prospects of soft bioelectronics for cardiac interfacing technologies are discussed.
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Affiliation(s)
- Sang Ihn Han
- Biomaterials Research Center, Biomedical Research Division, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Sung-Hyuk Sunwoo
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
- Department of Chemical Engineering, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Chan Soon Park
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
| | - Seung-Pyo Lee
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul 03080, Republic of Korea
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul 03080, Republic of Korea
| | - Taeghwan Hyeon
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Dae-Hyeong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering, and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
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Li H, Tan P, Rao Y, Bhattacharya S, Wang Z, Kim S, Gangopadhyay S, Shi H, Jankovic M, Huh H, Li Z, Maharjan P, Wells J, Jeong H, Jia Y, Lu N. E-Tattoos: Toward Functional but Imperceptible Interfacing with Human Skin. Chem Rev 2024; 124:3220-3283. [PMID: 38465831 DOI: 10.1021/acs.chemrev.3c00626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The human body continuously emits physiological and psychological information from head to toe. Wearable electronics capable of noninvasively and accurately digitizing this information without compromising user comfort or mobility have the potential to revolutionize telemedicine, mobile health, and both human-machine or human-metaverse interactions. However, state-of-the-art wearable electronics face limitations regarding wearability and functionality due to the mechanical incompatibility between conventional rigid, planar electronics and soft, curvy human skin surfaces. E-Tattoos, a unique type of wearable electronics, are defined by their ultrathin and skin-soft characteristics, which enable noninvasive and comfortable lamination on human skin surfaces without causing obstruction or even mechanical perception. This review article offers an exhaustive exploration of e-tattoos, accounting for their materials, structures, manufacturing processes, properties, functionalities, applications, and remaining challenges. We begin by summarizing the properties of human skin and their effects on signal transmission across the e-tattoo-skin interface. Following this is a discussion of the materials, structural designs, manufacturing, and skin attachment processes of e-tattoos. We classify e-tattoo functionalities into electrical, mechanical, optical, thermal, and chemical sensing, as well as wound healing and other treatments. After discussing energy harvesting and storage capabilities, we outline strategies for the system integration of wireless e-tattoos. In the end, we offer personal perspectives on the remaining challenges and future opportunities in the field.
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Affiliation(s)
- Hongbian Li
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Philip Tan
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yifan Rao
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Sarnab Bhattacharya
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zheliang Wang
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Sangjun Kim
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Susmita Gangopadhyay
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Hongyang Shi
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Matija Jankovic
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Heeyong Huh
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zhengjie Li
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Pukar Maharjan
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jonathan Wells
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Hyoyoung Jeong
- Department of Electrical and Computer Engineering, University of California Davis, Davis, California 95616, United States
| | - Yaoyao Jia
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Nanshu Lu
- Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
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Lee H, Kim HJ, Shin Y, Kim DH. Phase-separated stretchable conductive nanocomposite to reduce contact resistance of skin electronics. Sci Rep 2024; 14:1393. [PMID: 38228674 PMCID: PMC10791646 DOI: 10.1038/s41598-024-51980-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 01/11/2024] [Indexed: 01/18/2024] Open
Abstract
Skin electronics, facilitating a high-quality interface between external devices and human skin for recording physiological and/or electrophysiological signals as well as delivering external electrical and/or mechanical energy into the human body, has shown significant progress. However, achieving mechanically conformal contact and electrically low contact resistance at the device-skin interface remains challenging. Here, we propose a material strategy to potentially address such an issue by using phase separation of silver nanowires and silver nanoparticles (Ag NWs and Ag NPs) within a stretchable conductive nanocomposite (NC). This phase-separated NC ensures low contact resistance and high conductivity, which are key requirements in skin electronics, while maintaining excellent mechanical contact with the skin. To achieve phase separation, we hydrophobically treated the surfaces of Ag NWs and Ag NPs. Then, as the NC solidified, the solvent contained in the NC was slowly evaporated to sufficiently precipitate Ag NPs within the NC. As a result, the phase-separated NC exhibited high conductivity (~ 18,535 S cm-1), excellent stretchability (~ 80%), and low contact resistance on both the top and bottom NC surfaces (average ~ 0.132 Ω). The phase-separated NC has enabled implementation of high performance skin-mounted devices, including strain sensors, electrophysiological sensors, and a wearable heater.
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Affiliation(s)
- Hyunjin Lee
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hye Jin Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yoonsoo Shin
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea
| | - Dae-Hyeong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea.
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, 08826, Republic of Korea.
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
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Park H, Kim DC. Structural and Material-Based Approaches for the Fabrication of Stretchable Light-Emitting Diodes. MICROMACHINES 2023; 15:66. [PMID: 38258185 PMCID: PMC10821428 DOI: 10.3390/mi15010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 12/22/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024]
Abstract
Stretchable displays, capable of freely transforming their shapes, have received significant attention as alternatives to conventional rigid displays, and they are anticipated to provide new opportunities in various human-friendly electronics applications. As a core component of stretchable displays, high-performance stretchable light-emitting diodes (LEDs) have recently emerged. The approaches to fabricate stretchable LEDs are broadly categorized into two groups, namely "structural" and "material-based" approaches, based on the mechanisms to tolerate strain. While structural approaches rely on specially designed geometries to dissipate applied strain, material-based approaches mainly focus on replacing conventional rigid components of LEDs to soft and stretchable materials. Here, we review the latest studies on the fabrication of stretchable LEDs, which is accomplished through these distinctive strategies. First, we introduce representative device designs for efficient strain distribution, encompassing island-bridge structures, wavy buckling, and kirigami-/origami-based structures. For the material-based approaches, we discuss the latest studies for intrinsically stretchable (is-) electronic/optoelectronic materials, including the formation of conductive nanocomposite and polymeric blending with various additives. The review also provides examples of is-LEDs, focusing on their luminous performance and stretchability. We conclude this review with a brief outlook on future technologies.
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Affiliation(s)
- Hamin Park
- Department of Electronic Engineering, Kwangwoon University, 20, Gwangun-ro, Nowon-gu, Seoul 01897, Republic of Korea
| | - Dong Chan Kim
- Department of Chemical and Biological Engineering, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si 13120, Republic of Korea
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Zhu T, Wu K, Wang Y, Zhang J, Liu G, Sun J. Highly stable and strain-insensitive metal film conductors via manipulating strain distribution. MATERIALS HORIZONS 2023; 10:5920-5930. [PMID: 37873924 DOI: 10.1039/d3mh01399e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Metal film-based stretchable conductors are essential elements of flexible electronics for wearable, biomedical, and robotic applications, which require strain-insensitive high conductivity over a wide strain range and excellent cyclic stability. However, they suffer from serious electrical failure under monotonic and cyclic tensile loading at a small strain due to the uncontrolled film cracking behavior. Here, we propose a novel in-plane crack control strategy of engineering hierarchical microstructures to achieve outstanding electromechanical performance via harnessing the strain distribution in metal films. The wrinkles delay the crack initiation at undercuts which should be the most vulnerable sites during the stretching process. The surface protrusions/grooves/undercuts inhibit the crack propagation because of the effective strain redistribution. In addition, hierarchical microstructures significantly improve cyclic stability due to the strong interfacial adhesion and stable crack patterns. The metal film-based conductors exhibit ultrahigh strain-insensitive conductivity (1.7 × 107 S m-1), negligible resistance change (ΔR/R0 = 0.007) over an ultra-wide strain range (>200%), and excellent cyclic strain durability (>15 000 cycles at 100% strain). A range of metal films was explored to establish the universality of this strategy, including ductile copper and silver, as well as brittle molybdenum and high entropy alloy. We demonstrate the strain-insensitive electrical functionality of a metal film-based conductor in a flexible light-emitting diode circuit.
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Affiliation(s)
- Ting Zhu
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Kai Wu
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Yaqiang Wang
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Jinyu Zhang
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Gang Liu
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
| | - Jun Sun
- State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
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