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Dynamically responsive materials with chromotropic properties have received increasing attention in flexible pressure sensing due to their intuitive nature in the information transfer process. Here, inspired by the biological dynamic regulation of structural color in nature, a robust biomimetic mechanochromic photonic ionogel is ingeniously constructed. The photonic ionogel undergoes continuous and regular structural color changes under compression and outputs stable optical signals, possessing excellent linear pressure responsiveness and stability. The photonic ionogel exhibits sensitive changes in structural color and reflection wavelength via adjusting the lattice spacing of the 3D photonic crystal (mechanochromic sensitivity: 2.21 nm per %, Δλ > 150 nm). Furthermore, the good compatibility between ionogel and PC microspheres endows photonic ionogel with good linear pressure responsiveness (R2 ≈ 0.984). Meanwhile, ionic liquid (IL) and the covalent cross-linking network of robust polyurethane elastomer provide photonic ionogel with a wide temperature tolerance range (Tg ≈ −49.5 °C, initial decomposition temperature of 301 °C) and mechanical durability (5000 cycles of compression). This work demonstrates promising applications not only in flexible pressure sensing but also in advanced visual interaction devices. [ABSTRACT FROM AUTHOR]

The growing interest in mimicry of biological skins greatly promotes the birth of high‐performance artificial skins. Chameleon skins can actively transform environmental information into bioelectrical and color‐change signals simultaneously through manipulating ion transduction and photonic nanostructures. Here, inspired by chameleon skins, a novel biomimetic chromotropic photonic‐ionic skin (PI‐skin) capable of outputting synergistic electrical and optical signals under strain with robust adhesion, stability, and resilience is ingeniously constructed. The PI‐skin exhibits sensitive structural color change synchronized with electrical response via adjusting the lattice spacing of the photonic crystal (mechanochromic sensitivity: 1.89 nm per %, Δλ > 150 nm). Notably, the polyzwitterionic network provides abundant electrostatic interactions, endowing the PI‐skin with excellent adhesion, environmental tolerance, and outstanding mechanical stability (>10 000 continuous cycles). Meanwhile, the high loading of ionic liquid (IL) weakens the electrostatic interaction between the polyzwitterionic molecular chains, leading to high resilience. The PI‐skin is finally applied to construct a visually interactive wearable device, realizing precise human motion monitoring, remote communication, and visual localization of pressure distribution. This work not only expands design ideas for the construction of advanced biomimetic I‐skins but also provides a general optical platform for high‐level visual interactive devices and smart wearable electronics. [ABSTRACT FROM AUTHOR]

The integration of invisible photonic patterns into specific micro/nanostructures provides a new way to construct stimuli‐responsive optical anti‐counterfeiting devices. Herein, an innovative strategy for constructing highly invisible patterns in the solvent‐responsive double‐inverse‐opal (DIO) films by the thermal treatment is proposed. The masked area retains the responsive DIO structure, but the exposed area loses the periodic ordered array, which results in different optical responses of the pattern and background to the solvent. Due to the special structure, the scattering effect derived from the randomly distributed polystyrene microspheres within the pores of the inverse‐opal backbone in both the masked area and the exposed area makes the resultant film sample present a pale color, and the encrypted pattern is highly invisible in normal conditions. Interestingly, the hidden pattern can be quickly revealed by ethanol response, showing a large color contrast. Furthermore, reversible bilayer DIO films with multiple hidden patterns for advanced anti‐counterfeiting materials are prepared. Importantly, the as‐prepared film sample can reveal different patterns on the front and back sides in decryption, and simultaneously the overlapping part of the patterns can achieve color mixing based on the bilayer structure, thereby showing great potential in information encryption and anti‐counterfeiting fields. [ABSTRACT FROM AUTHOR]

Janus structure offers materials unique functionalities which are difficult to achieve otherwise with isotropic counterpart, opening up new avenues in diverse application fields. Here, a series of novel photonic Janus carbon fibers (PJCFs) with structural color gradient and excellent mechanical stability are reported by introducing 1D photonic layers with a gradient of periodicity. By virtue of the unique photonic architecture, the PJCFs exhibit a multiple and continuous variation of structural color (i.e., structural color gradient) in a full spectrum. By controlling the thickness of periodic layer, a series of PJCFs with vivid and tunable structural colors ranging from blue, green, orange, to violet‐red can be obtained. Furthermore, their gradient structural colors remain constant after reciprocating rubbing and laundering, showing outstanding mechanical robustness. Notably, benefiting from the inherent electrothermal property and flexibility of CFs, the PJCFs display stable Joule heating performance even under deformation. As proof‐of‐concept, the PJCFs are further integrated with wireless transmission system to construct a multicolored, wirelessly controlled thermal management device, realizing remote and precise temperature manipulation via Bluetooth. This work provides not only a new platform for achieving distinct structural color gradient of CFs, but also a promising strategy toward next‐generation multicolored personal healthcare devices. [ABSTRACT FROM AUTHOR]

Smart interactive electronic devices can dynamically respond to and visualize environmental stimuli. Inspired by the rapid color changes of natural creatures, an interactive electronic fiber sensor with high stretchability and tunable coloration is presented. It is based on an ingenious multi‐sheath design on a piezoresistive electronic fiber coupled with a mechanochromic photonic crystal microtubule. It has the unique capabilities of sensing and visualizing its deformation simultaneously, by reconstructing conductive paths and regulating the lattice spacing of the photonic sheath. In particular, it exhibits dynamic color switching spanning the full visible region (from red to blue), fast optical/electrical response (≈80 ms), and a large working range (0–200%), allowing its application as a user‐interactive sensor for dynamically monitoring large joint movements and muscle microvibrations of the human body in real time. This investigation provides a general platform for emerging interactive devices, which are promising for applications in wearable electronics, human–machine interactions, and intelligent robots. [ABSTRACT FROM AUTHOR]

Photonic‐ionic skins (PI‐skins) featuring multi‐signal synergistic outputs exhibit fascinating interactive sensing potential in flexible iononics. However, the existing ones are susceptible to irreversible damage in usage due to their poor toughness and deficiency in self‐healing. Herein, a novel tough mechanochromic PI‐skin is ingeniously constructed, from both molecular engineering and nanostructural engineering perspectives, via integrating the ordered photonic array and robust metal‐imidazole cross‐linked network. The PI‐skin displays synchronous structural color variation and sensitive electrical response under strain. Notably, the synergy of dense physical cross‐linking network and microphase‐separation structure achieved by strong metal‐imidazole coordination greatly promotes energy dissipation. PI‐skin possesses a combination of exceptional properties, including high fracture strength (8.22 MPa), remarkable toughness (10.23 MJ m−3), and robust adhesion behavior (2.30 MPa). Furthermore, favorable self‐healing capability at room temperature is realized thanks to the dynamic topological rearrangement of metal‐imidazole coordination. The PI‐skin demonstrates promising uses as a visually interactive wearable device for human motion monitoring and remote communication. This work not only broadens design considerations for the development of high‐performance artificial skins but also offers a general optical platform for high‐level interactive wearable devices. [ABSTRACT FROM AUTHOR]

• Photonic-ionic skin (PI-skin) is constructed with the fluorine-rich ionogel crosslinked by hindered urea bonds. • PI-skin exhibits strain-induced electrical/optical dual response synchronously. • PI-skin displays underwater stabilization, self-healing performance, and high resilience. • PI-skin demonstrates applications for dual-signal underwater sensing and wireless dual-encrypted information transmission. Bioinspired photonic-ionic skins (PI-skins) possessing multiple signals considerably promote the development of soft ionoelectronics owing to the fascinating interactive sensing capabilities. Unfortunately, swelling and leakage in aqueous environments are significantly detrimental to the stability and durability of underwater sensing. Herein, a novel PI-skin with waterproof, self-healing, and highly resilient properties is ingeniously fabricated via integrating the photonic array and dynamically covalently crosslinking fluorine-rich ionogel. Benefiting from the strain-modulated nanostructure and ionic conduction, the PI-skin achieves unique dual-signal sensing capability with sensitive mechanochromic performance and synchronous electrical response. Furthermore, the synergistic water repellency of the trifluoromethyl on the skeleton and the long alkyl chain modified hydrophobic ionic liquid (IL) inhibit swelling and leakage, significantly enhancing underwater stability. Notably, the exchangeable hindered urea bonds (HUBs) were judiciously introduced to construct a stable dynamically covalently crosslinking network, achieving efficient self-healing and high resilience simultaneously. The PI-skin with excellent adhesion and durability demonstrates the application potential in dual-signal underwater sensing and wireless information transmission. This work offers innovative design inspirations for the advancement of multifunctional artificial skins, intelligent interactive devices, and high-performance wearable iontronics. [ABSTRACT FROM AUTHOR]

• Photonic-ionic skin (PI-skin) is constructed by dynamic covalent crosslinked ionogel. • PI-skin exhibits electro-optical dual response under stretched/compressed. • PI-skin demonstrates robust resilience and high-efficiency self-healing. • A novel interactive human–machine interface is demonstrated based on the PI-skin. Advanced skin systems realize perception and interaction with the environment through synergistic electrical and color signals generated by transmitting ions and manipulating photonic structures. Here, inspired by chameleon skins, a novel self-healing and resilient photonic-ionic skin (PI-skin) with electro-optical dual response is ingeniously constructed integrating the ordered micro-nano array and the dynamically covalently cross-linked ionogel. The elaborately designed polycation network with weak inter-chain interactions can promote the uniform distribution of high-content low-viscosity ionic liquid (IL), effectively eliminating energy dissipation and resulting in high resilience. Dynamic acylhydrazone bonds are served as reversible chemical crosslinking to realize high-efficiency self-healing and further enhance resilience. Notably, the artificially manipulated transition of the photonic array from dense packing to non-dense packing endows sensitive chromotropic properties synchronized with electrical response under stretched (Δλ > 130 nm) and compressed (Δλ > 160 nm). Furthermore, by harnessing the correspondence between electrical and optical signals, the control of optical signals over electrical signals is achieved for inputting complex coded information and constructing interactive human–machine interfaces. This work not only inspires the design and construction of high-level artificial skins but also stimulates the development of visual interactive devices and smart electronic/ionic products. [ABSTRACT FROM AUTHOR]

• The first photonic vitrimer-based electronics (PVBEs) have been developed. • PVBEs demonstrate excellent mechanochromism and simultaneous electromechanical performance. • PVBEs show synchronous and ultrastable optical/electrical response. • PVBEs' optical functions can be self-healed while their electromechanical performances are stably maintained. • A novel wirelessly visualized sensor is demonstrated based on PVBEs. Flexible and stretchable electronics with mechanosensory functionality are highly desirable on account of their intriguing applications in smart wearable devices. Unfortunately, the susceptibility to structural damage and single electrical signal output restrict their further practical uses. Here, novel photonic vitrimer-based electronics (PVBEs) with self-healability and ultrastable visual-digital outputs are developed by harnessing vitrimer-induced structural evolutions of both photonic crystal (PC) and piezoresistive carbon textile. They demonstrate excellent strain sensing performances including synchronous electrical/optical response (0.25 s), high sensitivity (gauge factor, GF = 10.3), superior durability (>10000 cycles) and mechanochromism. Notably, dynamic covalent networks within vitrimer endow them self-healing ability of optical function, while the electromechanical performances are stably maintained benefiting from unique fully-embedded structure. Based on these merits, a new type of PVBE is demonstrated by incorporating wireless transmission system. Such a device can function as wirelessly visualized sensor for real-time tracking both large and subtle human movements with optical and electrical dual-signal feedbacks, realizing remote and precise visual-digital outputs. This work offers a versatile platform for emerging self-healing functional devices and visually interactive electronics, bringing huge developments in the era of the Internet of Things. [ABSTRACT FROM AUTHOR]

[Display omitted] • Large-area water rewriteable double-inverse opal film is prepared. • Ultrafast response time and robust water writing capability are obtained. • The retention time of written marks can be controlled. • Spatio-temporal colorful patterns are constructed. • Information security materials with multistate switching are designed. Photonic paper, as a crucial branch of the research of structural color materials, has attracted considerable attention. Herein, innovative large-area water rewriteable double-inverse opal (WRDIO) film with ultrafast response time (∼0.8 s) and robust writing capability is fabricated by introducing polyacrylamide gel into the double-inverse opal. The hydrophilic nature of the polyacrylamide gel can induce water to quickly penetrate the internal pores of the inverted opal backbone. Simultaneously, the randomly distributed polystyrene microspheres within the pores become ordered under the action of liquid buoyancy, which eliminates the scattering disturbance and makes the film switch to the structural color state. Importantly, the as-prepared WRDIO film can be erased and rewritten over 500 cycles without significantly reducing the color quality. Besides, the retention time of the written marks can be controlled by writing using water pens with different water outputs. Interestingly, responsive spatio-temporal colorful patterns could be achieved based on the different volatilities of written marks. Furthermore, advanced optical anti-counterfeiting material with multistate switching for information security is prepared based on controlled wettability. Given these superior properties, this novel WRDIO film provides a new solution for future applications of rewriteable paper. [ABSTRACT FROM AUTHOR]

• A novel interactively mechanochromic electronic textile sensor has firstly been proposed. • The sensor demonstrates negative electrical response and simultaneous mechanochromism upon stretching. • The sensor exhibits rapid and durable electrical/optical response. • The sensor shows bright structural colors, enhanced toughness and excellent mechanical resilience. • The sensor can be used as interactive wearable devices for monitoring various human joint movements. Textile-based electronic devices are significant components of emerging wearable electronics. However, the current textile-based electronics are limited by single electrical signal input/output, and unable to be visualized directly by human eyes, restricting their diverse applications in visualized human-interactive electronics. Here, we develop a series of novel interactively mechanochromic electronic textile (MET) sensors for visualized stretchable electronics. The MET sensors are based on the ingenious coupling of new supramolecular photonic elastomers (PEs) with hierarchical-fiber-structured conductive polyester textiles (CPTs). Benefiting from their semi-embedded structures, the MET sensors demonstrate not only distinct negative electrical response but also simultaneous mechanochromic capability upon stretching, via reconstructing conductive paths and adjusting the lattice spacing of the photonic crystals. Notably, the MET sensors exhibit bright structural colors, enhanced toughness (35.6 kJ m−3), excellent mechanical resilience, fast optical/electrical response (≈0.30 s) and recovery speed (≈0.22 s). Most importantly, the structural colors and electrical responses of the MET sensors remain constant even after 30,000 stretching/releasing cycles, showing outstanding mechanical stability, reliability, and excellent durability. Based on these merits, the MET sensors are used as visually interactive wearable devices for monitoring human joint movements in real time. This research provides a general platform for achieving visualized interaction of the electronic textiles, which shows great prospects in wearable devices, human–machine interfaces, and soft robotics. [ABSTRACT FROM AUTHOR]

Mechanical discoloration and non-discoloration materials have received intensive interest and have been strongly developed over the past few years for anti-counterfeiting, sensing, and packaging. However, the fabrication of mechanical response materials with both angle-dependent and angle-independent structural colors remains challenges. Large-area mechanochromic bilayer polydimethylsiloxane (PDMS) film with both angle-dependent and angle-independent structural colors have been prepared by using bottom-up bar-coating. The long-range disordered and short-range ordered polystyrene (PS) nanoarrays give the bilayer film angle-independent structural color. Meanwhile, the surface wrinkling triggered by stretching generates angle-dependent structural color. Moreover, PS nanoarray cracks and surface wrinkles caused by tensile increase the scattering effect of the bilayer film and decrease the transmittance of the light. Importantly, pressure-induced surface structure rearrangements can deprive wrinkling behavior. The pressure-encoded invisible complex information can be displayed reversibly by stretching. It has potential application value in complex information coding, display, and smart window. [Display omitted] • The bilayer large-area structure color film can be easily and quickly prepared by using bottom-up bar-coating. • The rigid PS nanoarrays show non-discoloration and the wrinkles display discoloration during the straining process. • The bilayer film has both angle-dependent and angle-independent structural colors. • We confirmed that pressure-induced surface structure rearrangements can deprive wrinkling behavior. • PS nanoarray cracks and wrinkles caused by tensile increase the scattering effect of the bilayer film. [ABSTRACT FROM AUTHOR]