Jeong-Yun Sun's research while affiliated with Seoul National University and other places
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Publications (94)
Soft systems that respond to external stimuli, such as heat, magnetic field, and light, find applications in a range of fields including soft robotics, energy harvesting, and biomedicine. However, most of the existing systems exhibit nondirectional, nastic movement as they can neither grow nor sense the direction of stimuli. In this regard, artific...
Repositioning is a common guideline for the prevention of pressure injuries of bedridden or wheelchair patients. However, frequent repositioning could deteriorate the quality of patient's life and induce secondary injuries. This paper introduces a method for continuous multi-site monitoring of pressure and temperature distribution from strategicall...
Mechanism of Stretchable Mechanochromic Color-Tuning
In article number 2202897, Su Seok Choi and co-workers reveal the color changing mechanism of electrically stretchable mechanochromic system. The hexagonally close-packed (HCP) nanostructure of organogels should experience lattice deformations during mechanochromic process. Using their in situ el...
Background
Although several studies on the Mg-Zn-Ca system have focused on alloy compositions that are restricted to solid solutions, the influence of the solid solution component of Ca on Mg-Zn alloys is unknown. Therefore, to broaden its utility in orthopedic applications, studies on the influence of the addition of Ca on the microstructural, mec...
Nitric oxide (NO) has been shown to promote revascularization and nerve regeneration after peripheral nerve injury. However, in vivo application of NO remains challenging due to the lack of stable carrier materials capable of storing large amounts of NO molecules and releasing them on a clinically meaningful time scale. Recently, a silica nanoparti...
Stretchable iontronics have recently been developed as an ideal interface to promote the interaction between humans and devices. Since the materials that use ions as charge carriers are typically transparent and stretchable, they have been used to fabricate devices with diverse functions with intrinsic transparency and stretchability. With the deve...
In contrast to nano‐processed rigid photonic crystals with fixed structures, soft photonic organic hydrogel beads with dielectric nanostructures possess advanced capabilities, such as stimuli‐responsive deformation and photonic wavelength color changes. Recenlty, advanced from well‐investigated mechanochromic method, an electromechanical stress app...
During the past decade, there has been extensive research toward the possibility of exploring magnesium and its alloys as biocompatible and biodegradable materials for implantable applications. Its practical medical application, however, has been limited to specific areas owing to rapid corrosion in the initial stage and the consequent complication...
Despite innovative advances in stent technology, restenosis remains a crucial issue for the clinical implantation of stents. Reactive oxygen species (ROS) are known to potentially accelerate re-endothelialization and lower the risk of restenosis by selectively controlling endothelial cells and smooth muscle cells. Recently, several studies have bee...
Structure changes mediated by anisotropic volume changes of stimuli‐responsive hydrogels are useful for many research fields, yet relatively simple structured objects have been mostly used due to limitation in fabrication methods. To fabricate complex 3D structures that undergo structure changes in response to external stimuli, we developed jammed...
In the semiconductor manufacturing process, the inner walls of the equipment are coated with yttrium-based oxides for etch resistance against plasma exposure. Yttrium oxyfluoride (YOF) particle synthesis and coating methods have been actively studied owing to their high erosion resistance compared to Y2O3 and Al2O3. Owing to the formation of a roug...
In the field of actuator materials, hydrogels that undergo large volume changes in response to external stimuli have been developed for a variety of promising applications. However, most conventional hydrogels are brittle and therefore rupture when they are stretched to moderate strains (~50%). Thus, gels to be used for actuators still require impr...
![Figure 1. Phase transition of the [EMIM] + [NO 3 ] − /PAAm ionogel. (a)...](publication/360565188/figure/fig1/AS:1179219983904794@1658159361932/Phase-transition-of-the-EMIM-NO-3-PAAm-ionogel-a-Schematic-illustration-of_Q320.jpg)
As the demand for energy storage devices increases, the importance of electrolytes for supercapacitors (SCs) is further emphasized. However, since ions in electrolytes are always in an active state, it is difficult to store energy for a long time due to ion diffusion. Here, we have synthesized a phase-transitional ionogel and fabricated an SC based...
Recent growing pursuit of skin-mountable devices has been impeded by complicated structures of most sensing systems, containing electrode grids, stacked multi-layers, and even external power sources. Here, we introduce a type of touch sensing, termed triboresistive touch sensing, for gridless touch recognition based on monolayered ionic power gener...
Triboresistive Touch Sensing In article number 2108586, Jeong‐Yun Sun and co‐workers report a novel type of touch sensing, termed triboresistive touch sensing, which is developed for self‐powered gridless touch recognition. An ionic poly(dimethylsiloxane) exhibiting high transmittance (96.5%), stretchability (539.1%), resilience (99.0%), and ionic...
Hydrogels are promising as materials for soft actuators because of qualities such as softness, transparency, and responsiveness to stimuli. However, weak and slow actuations remain challenging as a result of low modulus and osmosis-driven slow water diffusion, respectively. We used turgor pressure and electroosmosis to realize a strong and fast hyd...
In this paper, a helical fiber was fabricated through electrospinning by increasing the vapor pressure of the solvent, increasing the conductivity of the polymer solution and forming an uneven electrical field distribution around the jet. Fiber morphology during electrospinning of a dielectric polymer solution was observed to dramatically change fr...
This paper reports in-situ synthesis of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate silver nanoparticle (PEDOT:PSS-AgNP) composites without an acid catalyst via a spontaneous redox reaction between silver nitrate (AgNO3) and 3,4-ethylenedioxythiophene (EDOT). To investigate the effect of solvent on the formation of PEDOT:PSS and AgNP, ni...
Addressing osteochondral defects, the objective of current study was to synthesize bilayered hydrogel, where the cartilage layer was formed by alginate (Alg)-polyacrylamide (PAAm) with and without the addition of TGF-β3 and bone layer by laponite XLS/Alg-PAAm and characterize by in vitro and in vivo experiments. Exceeding the mechanical strength of...
Noncovalent hydrogels, compared to covalent hydrogels, have distinctive advantages including biocompatibility and self-healing property but tend to have poor mechanical robustness, thus restricting their application spectrum. A clue to increase utility of such soft hydrogels without chemical bulk modification can be witnessed in biological organ wa...
The importance of chitosan has been strongly emphasized in literature because this natural polymer could not only remove heavy metal ions in water but also have the potential for recyclability. However, reversible phase transition and its dynamics, which are highlighting areas of a recycle process, have not been studied sufficiently. Here, we prese...
Elasmobranch fishes, such as sharks, skates, and rays, use a network of electroreceptors distributed on their skin to locate adjacent prey. The receptors can detect the electric field generated by the biomechanical activity of the prey. By comparing the intensity of the electric fields sensed by each receptor in the network, the animals can perceiv...
Materials that transform shapes responding to external stimuli can bring unprecedented innovations to soft matter physics, soft robotics, wearable electronics, and architecture. As most conventional soft actuation technologies induce large deformations only in a preprogrammed manner at designated locations, the material systems capable of agile rev...
A numerical simulation for a radio frequency (RF) thermal plasma torch was carried out to identify the temperature and velocity distributions and determine the optimal design of a plasma system based on the coil turn and torch inner diameter parameters. Then, the optimized conditions of five coil turns and a torch inner diameter of 64 mm were appli...
Biodegradable electronics are disposable green devices whose constituents decompose into harmless byproducts, leaving no residual waste and minimally invasive medical implants requiring no removal surgery. Stretchable and flexible form factors are essential in biointegrated electronic applications for conformal integration with soft and expandable...
Organic neuromorphic computing/sensing platforms are a promising concept for local monitoring and processing of biological signals in real time. Neuromorphic devices and sensors with low conductance for low power consumption and high conductance for low‐impedance sensing are desired. However, it has been a struggle to find materials and fabrication...
Mg has received much attention as a next-generation implantable material owing to its biocompatibility, bone-like mechanical properties, and biodegradability in physiological environments. The application of various polymer coatings has been conducted in the past to reduce the rapid formation of hydrogen gas and the local change in pH during the in...
In response to the extensive utilization of ionic circuits, including in iontronics and wearable devices, a new method for fabricating a hydrogel-based ionic circuit on a polydimethylsiloxane (PDMS) microchip is reported. Prolonged UV/ozone oxidation combined with proper surface functionalizations and a novel microchip bonding method using thiol-ep...
Graphene is an optimal material to be employed as an ionic diffusion barrier because of its outstanding impermeability and chemical robustness. Indium tin oxide (ITO) is often used in perovskite light-emitting diodes (PeLEDs), and it can release indium easily upon exposure to the acidic hole-injection layer so that luminescence can be quenched sign...
Power generation through the thermoelectric (TE) effect in small-sized devices requires a submillimeter-thick film that is beneficial to effectively maintain ΔT compared with a micron-scale thin film. However, most TE thick films, which are fabricated using printing technologies, suffer from low electrical conductivity due to the porous structures...
Current implantable materials are limited in terms of function as native tissue, and there is still no effective clinical treatment to restore articular impairments. Hereby, a functionalized polyacrylamide (PAAm)-alginate (Alg) Double Network (DN) hydrogel acting as an articular-like tissue is developed. These hydrogels sustain their mechanical sta...
Electrical stimulation therapy has recently been suggested as a therapeutic modality to accelerate wound healing. Despite advancements in the development of flexible electronic devices for rapid wound recovery, current systems, which are fabricated from various metals, have mechanical discontinuities that have not been fully resolved, making them u...
With the growing risk of radiation exposure, there are growing interests in radiation shielding. Because most radiation shields are made from heavy metals, a need to develop a soft shield is raised to protect human body. However, because the shield can easily undergo a mechanical damage by an impact, it would be better to have self-repairing system...
Conventional organic light‐emitting devices without an encapsulation layer are susceptible to degradation when exposed to air, so realization of air‐stable intrinsically‐stretchable display is a great challenge because the protection of the devices against penetration of moisture and oxygen is even more difficult under stretching. An air‐stable int...
Existing gels are mostly polar, whose nature limits their role in soft devices. The intermolecular interactions of nonpolar polymer-liquid system are typically weak, which makes the gel brittle. Here we report highly soft and transparent nonpolar organogels. Even though their elements are only carbon and hydrogen, their elastic modulus, transparenc...
A number of implantable biomedical devices have been developed and wireless power transfer (WPT) systems are emerging as a way to provide power to these devices without requiring a hardwired connection. Most of WPT have been based on conventional conductive materials, such as metals, which tend to be less biocompatible and stiff. Herein, we describ...
With the rapidly growing attention to human-robot interfaces, soft robotics has attracted a great deal of interest. Soft robots have diverse advantages, including compliancy and safety, which contribute to seamless interactions with humans. To boost progress in the field, there is a need for compliant materials. Hydrogels are promising as compliant...
Spiders use adhesive, stretchable, and translucent webs to capture their prey. However, sustaining the capturing capability of these webs can be challenging because the webs inevitably invite contamination, thus reducing its adhesion force. To overcome these challenges, spiders have developed strategies of using webs to sense prey and clean contami...
Transparent and stretchable electrodes (TSEs) are a key technology for the next generation of stretchable electronics and optoelectronics. Metallic nanofibers are widely used because of their good optoelectrical properties, but they demonstrate low stretchability. To enhance stretchability, fabricating in‐plane buckled nanofibers with the aid of a...
Displays play a significant role in delivering information and providing visual data across all media platforms. Among displays, the prominence of reflective displays is increasing, in the form of E-paper, which has features distinct from emissive displays. These unique features include high visibility under daylight conditions, reduced eye strain...
Sonication of gallium or gallium-based liquid metals in an aqueous solution of vinyl monomers leads to rapid free radical polymerization (FRP), without the need for conventional molecular initiators. Under ambient conditions, a passivating native oxide separates these metals from solution and renders the metal effectively inert. However, sonication...
A hydrogel of covalently crosslinked chains and ionically crosslinked chains has exhibited high toughness. Under deformation, the covalently crosslinked network remains intact, and the ionically crosslinked network dissipates energy by breaking the ionic bonds. Because the broken ionic bonds can reform spontaneously, the damaged hydrogel can recove...
How can we modulate the inherent Poisson’s ratio value of soft elastomeric materials? The theoretical limit value of the Poisson’s ratio of isotropic materials can be defined from −1 to 0.5 but elastomers generally take the Poisson’s ratio of 0.5. Herein, we introduce and establish the concept of a mechanical meta elastomer called “auxetic elastome...
Significance
For intimate communication between electrical devices and biological areas, signal transfer in human–machine interfaces has become an issue due to differences in signal carriers. Furthermore, as the amount of ions acquired from biological systems is very small, amplification of weak ionic signals is required for effective signal proces...
According to the recent growth in interest of human-friendly devices, soft conductors, which are conductive materials with an inherent compliance, must have a low electrical strain sensitivity under large deformation conditions, environmental stability in water, and reliability even for complex and repeated deformation, as well as non-toxic charact...
As the demand for soft and flexible devices steadily increases, the ionic applications demonstrated with gel materials have come under the spotlight. Here, stretchable and wearable ionic diodes (SIDs) made from polyelectrolyte hydrogels are introduced. Polyelectrolyte hydrogels are mechanically modified using methacrylated polysaccharides while pre...
Color, as perceived through the eye, transcends mere information in the visible range of electromagnetism and serves as an agent for communication and entertainment. Mechanochromic systems have thus far only aimed at satisfying the sense of vision and have overlooked the possibility of generating acoustic vibrations in concert with their visual col...
In article number 1804080, Hyesung Cho, Jeong‐Yun Sun, and co‐workers demonstrate a pseudo‐synesthetic device that can generate color and sound simultaneously via a single input control. A soft photonic organogel is stretched by a dielectric elastomer actuator, allowing the synesthetic perception of sound and color to satisfy both senses of hearing...
Human skin exhibits high stiffness of up to 100 MPa and high toughness of up to 3600 J m⁻² despite its high water content of 40–70 wt%. Engineering hydrogels have rarely possessed both high stiffness and toughness, because compliant hydrogels usually become brittle when excess crosslinker is added to make the gel stiff. Furthermore, conventional hy...
As many devices for human utility aim for fast and convenient communication with users, superb electronic devices are demonstrated to serve as hardware for human–machine interfaces in wearable forms. Wearable devices for daily healthcare and self‐diagnosis offer more human‐like properties unconstrained by deformation. In this sense, stretchable ion...
Human–machine interfaces have benefited from the advent of wireless sensor networks and the internet of things, but rely on wearable/attachable electronics exhibiting stretchability, biocompatibility, and transmittance. Limited by weight and volume, wearable devices should be energy efficient and even self-powered. Here, we report practical approac...
Objective:
Susceptibility artifacts from metal clips in magnetic resonance (MR) imaging present an obstacle to evaluating the status of clipped aneurysms, parent arteries and adjacent brain parenchyma. We aimed to develop MR-compatible aneurysm clips.
Methods:
Considering the mechanical and biological properties, and MR compatibility of candidat...
Soft shields are required to protect the human body during a radioactive accident. However, the modulus of most soft shields, such as HDPE and epoxy, is high, thereby making it difficult to process them in wearable forms like gloves and clothes. We synthesized a soft shield based on a hydrogel that is very compliant, stretchable, and biocompatible....
A lithium (Li) metal anode is required to achieve a high-energy-density battery, but because of an undesirable growth of Li dendrites, it still has safety and cyclability issues. In this study, we have developed a microsphere-protected (MSP) Li metal anode to suppress the growth of Li dendrites. Microspheres could guide Li ions to selective areas a...
Herein, a facile approach for synthesizing mechanically enhanced nanocomposite hydrogels via a dual-crosslinking process is described. Additional ionic crosslinking using various cations is introduced after an in situ precipitation process for hydroxyapatite immobilization in hyaluronic acid hydrogels (HAc–CaP). Ca2+, Ba2+, and Sr2+ ions exhibit th...
Protein-based hydrogels have received attention for biomedical applications and tissue engineering because they are biocompatible and abundant. However, the poor mechanical properties of these hydrogels remain a hurdle for practical use. We have developed a highly stretchable and notch-insensitive hydrogel by integrating casein micelles into polyac...
Soft and still responsive
Transparent touch screens, from large-panel interactive information maps to advanced cell phones, have become a part of daily life. However, such devices all use hard materials. Kim et al. have developed a soft touch panel based on polyacrylamide hydrogels (cross-linked polymers swollen with water) that are highly transpar...
Unlabelled:
Organogel-based stretchable electronic conductors exhibit electrical conduction even under a large stretching deformation of 300% without electrochemical reactions at DC voltages. The resistance change with stretching is almost strain-insensitive up to 50% strain and it remains at each deformation up to 1000 fatigue cycle. The polymeri...
Alginates can be crosslinked with multivalent cations, leading eventually to hydrogel formation. The properties of alginate gel depend on its lock structure, monomeric composition, concentration of polymer and cross linker. Among these, the properties of ionically crosslinked alginate gel can be greatly affected by multivalent cations as cross-link...
Many flexible electronic devices contain metal films on polymer substrates to satisfy requirements for both electrical conductivity and mechanical durability. Despite numerous trials to date, the stretchability of metal interconnects remains an issue. In this paper, we have demonstrated a stretchable metal interconnect through control of the textur...
A highly elastic hybrid hydrogel of methacryloyl-substituted recombinant human tropoelastin (MeTro) and graphene oxide (GO) nanoparticles are developed. The synergistic effect of these two materials significantly enhances both ultimate strain (250%), reversible rotation (9700°), and the fracture energy (38.8 ± 0.8 J m(-2) ) in the hybrid network. F...
A strong isotropic material that is both biocompatible and biodegradable is desired for many biomedical applications, including rotator cuff repair, tendon and ligament repair, vascular grafting, among others. Recently, we developed a technique, called "bioskiving" to create novel 2D and 3D constructs from decellularized tendon, using a combination...
Using strong fibers to reinforce a hydrogel is highly desirable but difficult. Such a composite would combine the attributes of a solid that provides strength and a liquid that transports matter. Most hydrogels, however, are brittle, allowing the fibers to cut through the hydrogel when the composite is loaded. Here we circumvent this problem by usi...
Electronic skins (i.e., stretchable sheets of distributed sensors) report signals using electrons, whereas natural skins report signals using ions. Here, ionic conductors are used to create a new type of sensory sheet, called "ionic skin". Ionic skins are highly stretchable, transparent, and biocompatible. They readily measure strains from 1% to 50...
