Infrared metamaterial absorbers underpin many entrenched scientific and technical applications, including radiative cooling, energy harvesting, infrared detectors, and microbolometers. However, achieving both perfect and ultra-broadband absorption remains an unmet scientific challenge because the traditional metamaterial absorber strategy suffers from complex multi-sized resonators and multiple meta-element patterns. We demonstrate a simple ultra-broadband infrared metamaterial absorber consisting of tilted graphite wires and an Al reflector. The proposed tilted wires-based metamaterial (TWM) absorber exhibits absorption of above 0.95 across the middle to very long-wavelength infrared spectrum (3–30 µm). By increasing the aspect ratio, the bandwidth can be expanded and achieve near-perfect absorption in the 3–50 μm spectral range. The excellent infrared absorptance performance primarily originates from the ohmic loss induced by the electromagnetic coupling between neighboring tilted wires. Furthermore, we propose a typical three-layer equivalent model featuring a resonator/insulator/reflector configuration that requires more than 84 resonant cavities to obtain comparable infrared absorptance. Our high-performance TWM absorber could accelerate the development of next-generation infrared thermal emitters and devices and other technologies that require infrared absorption.

Dynamic infrared radiation regulation has been widely explored for smart windows because of its vital importance for comfortable and energy-efficient buildings. However, it remains a great challenge to synchronously achieve high visible transmittance and pronounced infrared tunability. Here, we propose a dynamic infrared tunable metamaterial composed of indium tin oxide (ITO) gratings, an air insulator, and an ITO reflector. The ITO grating-based infrared radiation regulator exhibits a high emissivity tunability of 0.73 at 8-13 μm while maintaining a high visible transmittance of 0.65 and 0.72 before and after actuation, respectively. By adjusting the geometric parameters, the tunable bandwidth can be further extended to 3-30 μm and the ultra-broadband tunability reaches 0.62. The excellent infrared tunable performance arises from the insulator thickness-dependent effect of Fabry-Pérot and propagating surface plasmon resonance coupling and decoupling, which lead to perfect and low absorption, respectively. This work provides potential for the advancement of smart window technology and makes a significant contribution to sustainable buildings.

Acquiring physical and mechanical strain information of the human body with wearable strain sensors can provide essential data from personal healthcare to human-machine interfaces and others. Recent research reveals that CO2 laser scribing can convert polyimide films into porous graphene sponges under ambient atmospheres. However, the electrically conductive laser-induced graphene (LIG) film mismatches with the tough and rigid plastic substrates when it is employed as stretchable strain sensors. In this work, by leveraging the advantageous properties of atoms-level configured defects within crystalline LIG and heat transfer printing techniques, a flexible LIG-SEBS (styrene-ethylene-butylene-styrene) strain sensor is made. It is able to achieve exceptional electromechanical properties including a remarkable sensitivity in terms of gauge factor (413-3118), minimal hysteresis, and a broad strain range (>100% strain). Meanwhile, the SEBS-LIG strain sensor has a stable and fast dynamic response and good repeatability. Additionally, the sensor can be integrated with a wireless communication module for remote monitoring of physiological signals in a real-time manner with a smartphone App.

The manipulation of interactions between light and matter plays a crucial role in the evolution of organisms and a better life for humans. As a result of natural selection, precise light-regulatory systems of biology have been engineered that provide many powerful and promising bioinspired strategies. As the "king of disguise", cephalopods, which can perfectly control the propagation of light and thus achieve excellent surrounding-matching via their delicate skin structure, have made themselves an exciting source of inspiration for developing optical and thermal regulation nanomaterials. This review presents cutting-edge advancements in cephalopod-inspired optical and thermal regulation nanomaterials, highlighting the key milestones and breakthroughs achieved thus far. We begin with the underlying mechanisms of the adaptive color-changing ability of cephalopods, as well as their special hierarchical skin structure. Then, different types of bioinspired nanomaterials and devices are comprehensively summarized. Furthermore, some advanced and emerging applications of these nanomaterials and devices, including camouflage, thermal management, pixelation, medical health, sensing and wireless communication, are addressed. Finally, some remaining but significant challenges and potential directions for future work are discussed. We anticipate that this comprehensive review will promote the further development of cephalopod-inspired nanomaterials for optical and thermal regulation and trigger ideas for bioinspired design of nanomaterials in multidisciplinary applications.

Dynamic thermal emission control has gained increasing attention across diverse fields. Among phase change materials (PCMs), SmNiO3 has attracted many interests because of its fast phase transition and non-volatile properties. However, constructing an emissivity modulation metamaterial with angle stability performance is still rather challenging. In this work, we propose three kinds of SmNiO3-based metamaterials for mid-infrared emissivity dynamic modulation, specifically a trapezoidal metamaterial consisting of alternating SmNiO3 and Si multi-layer thin films and two modified grating metastructures, realizing an average emissivity modulation Δεaver of 0.42–0.45 in 5–16 µm. It is confirmed that the magnetic resonance stimulated inside the metamaterial is because of the slow-light effect. This work provides theoretical fundamentals for the design of dynamic thermal control metamaterials and benefits applications in the fields of infrared emission modulation.

Thermal management is of great significance for human activities. Attaining thermal comfort not only requires thermal control of building's macroenvironment, but also additionally personal thermal regulation. Radiative cooling technologies are anticipated to effectively lower building energy utilization and provide optimal thermal comfort for individuals in hot weather. Nevertheless, these static and single-purpose characteristics lack the ability to adjust to rapidly changing weather conditions, often leading to excessive cooling. To overcome this challenge, the emergence of dual-mode smart flipping technologies has provided a pathway for dynamically adjusting the heating or cooling of objects in response to fluctuations in ambient temperature. First, the underlying principles of dual-mode smart flipping are shown. Then the evolving materials and approaches of smart flipping are given an introduction to adapt to different environments under external stimuli, such as mechanical flipping, temperature, humidity, and so forth. Afterward, we present the recent applications of dual-mode smart flipping materials and devices in personal thermal management, thermoelectric generation, energy-saving buildings, and smart windows. Finally, the challenges and outlook of dual-mode smart flipping are presented and future directions are identified.

In heat-assisted magnetic recording (HAMR), a laser is introduced to create a hot spot on the media and locally heat the magnetic layer to its Curie temperature. Besides the optical power that the laser provides to the media, thermal energy diffuses inside the slider and induces an extra protrusion, which is called laser-induced protrusion (LIP). The LIP needs to be considered and compensated during flying in the HAMR conditions. In this study, we focus on long timescale (milliseconds) of laser heating during the flying condition. When the laser is switched from OFF to ON, the touchdown power, indicated by an acoustic emission (AE) sensor, decreases due to spacing loss and the touchdown power change (DTDP) is used as the measure of the LIP. A component-level spinstand stage for HAMR heads and media is used to study the LIP as a function of laser-on time, laser current and linear velocity. Our experimental results show that it takes around 20 ms for the LIP to reach steady state and the protrusion size is proportional to the square of laser current. As the operating linear velocity increases from 12 m/s to 24 m/s, the LIP decreases by approximately 52%.

In heat-assisted magnetic recording (HAMR), a laser is employed above the read-write transducer to provide energy to the media, lowering its coercivity. However, the laser also brings thermal energy diffusion inside the slider and induces an extra angstrom-level protrusion, which we call laser-induced protrusion (LIP). The LIP needs to be taken into consideration in HAMR due to the significance of head-media spacing. This paper focuses on laser heating on the millisecond timescale during flying in the HAMR conditions. When the laser is turned ON for milliseconds, the LIP forms in the short term (∼μs) and fly height change (FHC) happens in the long term (∼ ms) due to the crown/camber change, resulting in a smaller touchdown power (TDP). Thus, the touchdown power change (ΔTDP) is measured and the LIP is isolated using the time constants. A component-level HAMR stage is used to study the effects of laser-on time, laser current, and linear velocity on the ΔTDP. The experimental results show that the FHC needs ∼ 28 ms to reach the steady state and that the protrusion size presents a two-stage linear relation with the laser current separated by a threshold. The LIP size is reduced by about half when operating from 12 m/s to 24 m/s.