Multimode interactive displays utilizing more than two stimulus-responsive light manipulation schemes have attracted considerable attention. However, sensing displays with asynchronous light control—where two responsive optical phenomena are complementary, thereby minimizing interference between two optical modes—have seldom been demonstrated. Here we report a novel self-assembled material exhibiting asynchronous fluorescence (FL) and structural color (SC), which enables multilevel optical sensing and encryption. Asynchronous FL and SC was achieved by chemically doping aggregation-induced emission luminogens (AIEgens) into one-dimensional block copolymer (BCP) photonic crystals (PCs) comprising alternating lamellae of two dielectric components. The AIEgen-derived FL of a nonswollen BCP PC with no visible SC was deactivated when it was swollen in a solvent, consequently exhibiting fully visible SC. The complementary FL and SC manipulation through reversible molecular (aggregation vs. separation) and structural (nonswollen vs. swollen) alteration aided in developing a multimode sensing display, which could detect temperature and/or nitroaromatic gas in FL mode as well as the pH of a solution in SC mode. The AIEgen-doped BCP PC exhibiting asynchronous FL and SC assisted in constructing a novel write-once-read-many optical encryption system with multilevel security where three levels of quaternary code-type passwords were encrypted with SC, FL, and pH-matched SC.

This comprehensive review explores the emerging field of bioinspired hydrovoltaic electricity generators from elementary bioinspired materials to smart bioinspired structures and living bioinspired devices.

Tactile skin with artificial mechanoreceptors can perceive static pressure and dynamic vibrations. However, the complexity of these tactile sensing systems has challenges in power consumption and recyclability. We present a dual-mode energy-generating skin (EG skin) capable of self-powered haptic sensing using a biodegradable hygroscopic film based on silk fibroin and phytic acid. At 85% relative humidity (RH), this EG skin generates an open-circuit voltage of 1 V and a maximum short-circuit current density of 110 mA cm-2 via moist-electric generators (MEGs). At ambient 35% RH, it produces a dual-mode energy output of 8.4 mW cm-2 by combining a triboelectric nanogenerator (TENG) with a MEG. Static pressure and dynamic vibration sensing are demonstrated through the coupling of the TENG and MEG.

Tactile visual synapses combine the functionality of tactile artificial synapses with the ability to visualize their activity in real time and provide a direct and intuitive visualization of the activity, offering an efficient route for in situ health monitoring. Herein we present a tactile visual synapse that enables in situ monitoring of finger rehabilitation and electrocardiogram analysis. Repetitive finger flexion and various arrhythmias are monitored and visually guided using the developed tactile visual synapse combined with an electrical and optical output feedback algorithm. The tactile visual synapse has the structure of an electrochemical transistor comprising an elastomeric top gate as a tactile receptor and an electrochemiluminescent ion gel as a light-emitting layer stacked on a polymeric semiconductor layer, forming an electrical synaptic channel between source and drain electrodes. The low-power (~34 μW) visualization of the tactile synaptic activity associated with the repetitive motions of fingers and heartbeats enables the development of a convenient and efficient personalized healthcare system.

Despite the remarkable progress in the development of sweat sensors, self-powered sweat-responsive sensing displays that detect sweat in electric signals with simultaneous and direct visualization of the sweat is rarely demonstrated. Here, a self-powered sweat-responsive structural color (SC) display enabled by ionomer-doped block copolymer (BCP) photonic crystals (PCs) is presented. The sweat-responsive BCP PC is developed by employing a cross-linking single-mobile ionomer (SMI) with mobile anions anchored to immobile polycations to a 1-D BCP PC. The hydrophobic SMI-doped BCP PC is mechanically robust as well as water and temperature-resistive, exhibiting ionomer concentration-dependent full visible SCs. Moreover, the mobile anions periodically confined in the SMI-doped BCP PC harvest triboelectric energy, giving rise to a high-power density of approximate to 0.774 Mw cm-2. Cation-sensitive SC variation is observed in the SMI-doped BCP PC, allowing the visualization of sweat containing various cations. A skin-patchable self-powered sweat-responsive display is demonstrated in which kirigami-patterned SMI-doped BCP PC incorporated in the display can withstand up to 50% strain during exercise. Sweat from the exercise is visualized via SC display and measured using both ionic resistance changes and triboelectric signals. In addition, the integration of sweat sensing membrane into SMI-doped BCP PC enables the quantification of sweat. A self-powered sweat-responsive sensing display enabling ionic as well as triboelectric detection of sweat with its simultaneous and direct structural color visualization is demonstrated, based on sweat-responsive block copolymer photonic crystals doped with single-mobile ionomer. Furthermore, by employing cation-selective membranes to the sensing display, the sweat is quantified in addition to the visualization of sweat. image

Optical encryption using coloration and photoluminescent (PL) materials can provide highly secure data protection with direct and intuitive identification of encrypted information. Encryption capable of independently controlling wavelength-tunable coloration as well as variable light intensity PL is not adequately demonstrated yet. Herein, a rewritable PL and structural color (SC) display suitable for dual-responsive optical encryption developed with a stimuli-responsive SC of a block copolymer (BCP) photonic crystal (PC) with alternating in-plane lamellae, of which a variety of 3D and 2D perovskite nanocrystals is preferentially self-assembled with characteristic PL, is presented. The SC of a BCP PC is controlled in the visible range with different perovskite precursor doping times. The perovskite nanocrystals developed in the BCP PC are highly luminescent, with a PL quantum yield of ≈33.7%, yielding environmentally stable SC and PL dual-mode displays. The independently programmed SC and PL information is erasable and rewritable. Dual-responsive optical encryption is demonstrated, in which true Morse code information is deciphered only when the information encoded by SCs is properly combined with PL information. Numerous combinations of SC and PL realize high security level of data anticounterfeiting. This dual-mode encryption display offers novel optical encryption with high information security and anti-counterfeiting.

Moisture-driven electricity generators (MEGs) have been extensively researched; however, high-performance flexible variants have seldom been demonstrated. Here we present a novel complex coacervation with built-in potential strategy for developing a high-performance uniaxial MEG, featuring a core of poly(3,4-ethylenedioxythiophene) (PEDOT) with a built-in charge potential and a gel shell composed of poly(diallyldimethylammonium chloride) (PDDA) and sodium alginate (NaAlg) coacervate. The complex coacervation of two oppositely charged polyelectrolytes produces extra mobile carriers and free volume in the device; meanwhile, the PEDOT core's surface charge significantly accelerates carrier diffusion. Consequently, the uniaxial fiber-based MEG demonstrates breakthrough performance, achieving an output voltage of up to 0.8 V, a maximum current density of 1.05 mA/cm2, and a power density of 184 mu W/cm2 at 20% relative humidity. Moreover, the mechanical robustness is ensured for the PEDOT nanoribbon substrate without performance degradation even after 100,000 folding cycles, making it suitable for self-powered human interactive sensor and synapse. Notably, we have constructed the inaugural MEG-synapse self-powered device, with a fiber-based MEG successfully operating a synaptic memristor, thereby emulating autonomous human synapses linked with fibrous neurons. Overall, this work pioneers innovative design strategies and application scenarios for high-performance MEGs. The authors present a core-shell fiber moisture-driven electric generator by a synergetic complex coacervation and built-in potential strategy, enabling self-powered human interactive sensors and synaptic devices.

A deformable complementary energy harvester combining moisture-induced and triboelectric energy in a single cell is developed, offering mechanical resilience, high energy output, rapid capacitor charging, and potential in emergency guidance systems.

Despite significant progress in developing artificial synapses to emulate the human nervous system for bio-signal transmission, synapses with thermo-adaptive coloration and soft actuators driven by temperature change have seldom been reported. Herein, a photonic neuro-actuating synaptic skin is presented enabling thermoresponsive synaptic signal transmission, color variation, and actuation. First, a thermoresponsive display synapse is developed based on a 3-terminal ion-gel transistor with a poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) semiconducting channel mixed with 2D titanium carbide (Ti3C2Tx) MXene and a thermo-adaptive 1D block copolymer (BCP) photonic crystal (PC) gate insulator. Temperature-dependent synaptic behavior is successfully observed in the ion-gel transistor with the corresponding structural colors, leading to a thermo-adaptive display synapse. The 3 × 3 arrays of thermo-adaptive display synapses with Joule heaters show that each pixel is controlled by the thermoresponsive structural color and synaptic output. The synaptic output current from the MXene ion-gel transistor can be converted and amplified to a voltage signal, which powers a soft actuator connected to the ion-gel display synapse and triggers temperature-dependent actuation related to the thermoresponsive synaptic performance. This study showcases a thermo-adaptive photonic neuro-actuating artificial skin that emulates muscle-combined neuronal human skin with visualization capability.

An additive, 1,4‐butadiene sulfone (BDS), which generates H 2 SO 3 by in situ thermal retro‐Diels‐Alder decompositions, is used for preparing high β‐phase polyvinylidene fluoride (PVDF) films. Because of preferential multiple non‐covalent interactions of H 2 SO 3 with all‐trans configuration of PVDF, β‐phase PVDF is spontaneously induced without mechanical drawing and/or extensive thermal annealing process. PVDF films cast from PVDF/BDS/water solutions exhibit high β‐phase content ( f β = 95%) when the BDS concentration is only c BDS = 1.0 wt%, which is confirmed by polarized optical microscopy (POM), SEM, Fourier transform infrared spectroscopy (FT‐IR), differential scan calorimetry (DSC), and 2D grazing incidence wide‐angle X‐ray scattering (GIWAXS). Because of the high β‐phase content, PVDF films prepared by using BDS exhibit excellent ferroelectric and piezoelectric properties ( E c = 50 MV/m, P r = 5 µC/cm 2 , and d 33 = ≈‐25 pm/V). Furthermore, a triboelectric nanogenerator (TENG) developed with high β‐phase PVDF film exhibits enhanced performance as 2.5 times higher than neat PVDF film in output charge density, allowing reliable operation of conventional electronic devices.

Free-standing and film-type moisture-driven energy generators (MEGs) that harness the preferential interaction of ionized moisture with hydrophilic materials are interesting because of their wearability and portability without needing a water container. However, most such MEGs work in limited humidity conditions, which provide a substantial moisture gradient. Herein, we present a high-performance MEG with sustainable power-production capability in a wide range of environments. The bilayer-based device comprises a negatively surface-charged, hydrophilic MXene (Ti3C2Tx) aerogel and polyacrylamide (PAM) ionic hydrogel. The preferential selection on the MXene aerogel of positive charges supplied from the salts and water in the hydrogel is predicted by the first-principle simulation, which results in a high electric output in a wide relative humidity range from 20% to 95%. Furthermore, by replacing the hydrogel with an organohydrogel of PAM that has excellent water retention and structural stability, a device with long-term electricity generation is realized for more than 15 days in a broad temperature range (from -20 to 80 °C). Our MXene aerogel MEGs connected in series supply sufficient power for commercial electronic components in various outdoor environments. Moreover, an MXene aerogel MEG works as a self-powered sensor for recognizing finger bending and facial expression.

Ionic thermoelectric supercapacitors (ITESCs) produce orders of magnitude higher voltages than those of con-ventional thermoelectrics (TEs) based on the thermo-diffusion of electrons/holes and are therefore attractive for converting low-grade heat into electricity. The stretchability and stability of the whole ITESC are important for wearable heat harvesting applications. Recent studies on ITESC have focused on stretchable ionic TE electrolytes with a giant Seebeck coefficient, but there are no reports of fully stretchable ITESCs for wearable heat harvesting devices due to the lack of stretchable electrodes and stretchable ionic TE electrolytes with stability. Herein, we present a fully stretchable ITESC composed of stable high-performance ionic thermoelectric elastomer (ITE) electrolyte and stretchable gold nanowire (AuNW) electrodes. The ITE shows excellent air stability (> 60 d) in comparison to hydrogel-based electrolytes that are susceptible to dehydration in ambient conditions. Further-more, the ITE exhibits an apparent thermopower up to 38.9 mV K-1 and ionic conductivity of 3.76 x 10-1 mS cm-1, which both are maintained up to a tensile strain of 250%. Finally, a fully stretchable ITESC with AuNW electrodes is developed which can harvest energy from thermal gradients during deformations.

Dual-mode optical encryption based on holographic metasurfaces and color components is of great attraction because of their enhanced information security and storage; however, the realization of independently as well as reversibly encodable holographic metasurfaces and color components remains unreported. Herein, we present reconfigurable dual-mode encryptions of structural colors (SC) and holograms, achieved through stimuli-responsive block copolymer (BCP) photonic crystals (PCs) with micro-imprinted holographic metasurfaces. Holographic images appear when the micro-imprinted BCP PCs, consisting of self-assembled alternating lamellae of two dielectrics, are exposed to an incident laser. A characteristic SC develops in the visible range when the imprinted film is immersed in a liquid agent that can swell one of the dielectrics, allowing for dual-mode holographic and SC encodings in the solid and liquid states, respectively. The dual-mode optical encoding is reconfigured. The holographic image can be erased and replaced with another micropattern, while preserving the SC. Moreover, an SC, set by crosslinking of the swellable lamellae, is reset by chemical de-crosslinking and subsequent transient re-crosslinking, enabling the SC reconfigurability of the BCP PC film. A prototype of a high-security reconfigurable dual encryption has been developed, wherein true information is decrypted when holographic passwords are confirmed with full-color visible SC passwords.

Self-powered user-interactive displays that facilitate the visualization of human information acquired by sensors are of great interest in emerging human–machine interface technology with efficient energy consumption. Herein, a self-powered motion-sensing display capable of simultaneously detecting and visualizing finger motions is presented. Our device is based on a one-dimensional photonic crystal of an interpenetrated hydrogel network block copolymer (IHN-BCP) consisting of alternating water-absorbable and non-absorbable lamellae. Triboelectrification is achieved as a function of relative humidity from 30% to 80%. The direct visualization of the humidity is also achieved through the humidity-dependent structural color of the photonic crystal in the full visible range. Furthermore, the humidity-responsive triboelectrification and structural color of our IHN-BCP photonic crystal facilitates the development of a self-powered finger motion-sensing display where diverse gestures of a finger with natural humidity are quantitatively recognized, such as vertical and sliding motion of the finger with simultaneous visualization of the motions in both contact and non-contact modes.

Liquid-free ionic conductors, known as ionoelastomers, are of great interest because of their potential for developing reliable and resilient ionic devices with elastic mechanical properties. This study presents an intrinsically stretchable diode consisting of a highly stretchable ionoelastomer bilayer vertically stacked with liquid metal electrodes. The bilayer contains two types of ionoelastomer networks: one containing fixed anions with mobile cations and one containing fixed cations with mobile anions. Both ionoelastomers use 2-hydroxyethyl acrylate to provide high stretchability. The junction between the two ionoelastomers creates a diode with excellent non-Faradaic ionic current rectification. The voltage-dependent modulation of the ionic double layer at the interface between the two ionoelastomers provides the rectification. The elastic diode works under cyclic loading to a uniaxial stretch ratio of 6 (strain of 500%), allowing the development of a highly stretchable ionic OR logic gate.

Advanced Energy MaterialsVolume 11, Issue 6 2170024 Cover PictureFree Access Li-Ion Batteries: Conductor-Free Anode of Transition Metal Dichalcogenide Nanosheets Self-Assembled with Graft Polymer Li-Ion Channels (Adv. Energy Mater. 6/2021) Chanho Park, Chanho Park Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorYoung Hwan Kim, Young Hwan Kim Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorHyeokjung Lee, Hyeokjung Lee Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorHan Sol Kang, Han Sol Kang Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorTaebin Kim, Taebin Kim Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorSeung Won Lee, Seung Won Lee Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorKyuho Lee, Kyuho Lee Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorKwang-Bum Kim, Kwang-Bum Kim Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorCheolmin Park, Cheolmin Park Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this author Chanho Park, Chanho Park Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorYoung Hwan Kim, Young Hwan Kim Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorHyeokjung Lee, Hyeokjung Lee Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorHan Sol Kang, Han Sol Kang Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorTaebin Kim, Taebin Kim Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorSeung Won Lee, Seung Won Lee Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorKyuho Lee, Kyuho Lee Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorKwang-Bum Kim, Kwang-Bum Kim Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this authorCheolmin Park, Cheolmin Park Department of Materials Science and Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul, 03722 Republic of KoreaSearch for more papers by this author First published: 11 February 2021 https://doi.org/10.1002/aenm.202170024AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract In article number 2003243, Cheolmin Park and co-workers develop a novel transition metal dichalcogenide nanosheet anode that features self-assembled ionic nanochannels of a graft ionomer binder. The ionic channels on the dispersed nanosheets induce the stable operation of a lithium-ion battery with high capacity and rate capability, which does not need conductor additives and expensive accessory processes. Volume11, Issue6February 11, 20212170024 RelatedInformation

The development of anodes for lithium‐ion batteries (LIBs) based on liquid‐phase‐exfoliated 2D transition metal dichalcogenide (TMD) nanosheets has been studied extensively because their intrinsic capacity is higher than graphite. Since most semiconducting TMDs possess low electrical conductivity and lithium‐ion diffusivity, expensive processes are necessary such as the addition of conductive fillers, chemically converted metallic phase transformation, and topological nano‐fabrication. Here, a novel conductor‐free TMD nanosheet anode with graft‐polymer ionic channels that ensures high stability and rate capability of the LIB is presented. The fluorinated polymer binder grafted with ionomers allows not only the efficient exfoliation of TMD nanosheets in the liquid phase to guarantee stable sheet‐to‐sheet separation but also provides self‐assembled ionic channels through which lithium ions in the electrolyte readily arrive close to the surface of the nanosheets. Efficient electrochemical reduction of lithium ions occurs on the surface of the binary anode of MoS 2 nanosheets, self‐assembled with graft polymer ionic channels, resulting in a high‐performance LIB with stability (90% retention rate after 1,000 cycles), rate capability (50% at 5 A g −1 ), and high cell capacity (933.1 mAh g −1 at 0.1 A g −1 ). These TMD anodes that do not require additional processes, and offer a novel strategy for developing high performance large‐scale TMD‐based LIBs.

Artificial photonic synapses with morphologically controlled photoreception, allowing for area‐dependent tunable light reception as well as information storage and learning, have potential for application in emerging photo‐interactive neuro‐computing technologies. Herein, an artificially intelligent (AI) photonic synapse with area‐density‐tunable perovskite nano‐cone arrays templated in a self‐assembled block copolymer (BCP) is presented, which is based on a field effect transistor with a floating gate of photoreceptive perovskite crystal arrays preferentially synthesized in a micro‐phase‐segregated BCP film. These arrays are capable of electric charge (de)trapping and photo‐excited charge generation, and they exhibit versatile synaptic functions of the nervous system, including paired‐pulse facilitation and long‐term potentiation, with excellent reliability. The area‐density variable perovskite floating gate developed by off‐centered spin coating process allows for emulating the human retina with a position‐dependent spatial distribution of cones. 60 × 12 arrays of the developed synapse devices exhibit position‐dependent dual functions of receptor and synapse. They are AI and exhibit a pattern recognition accuracy up to ≈90% when examined using the Modified National Institute of Standards and Technology handwritten digit pattern recognition test.