DOI: 10.1002/aenm.201903921 us warm in cold climates and shielded us from the nakedness for modesty and civilization.[1,2] Cloth is also a platform for artists, designers, and tailors to advance the clothing demands with emerging materials, process, and fashion.[2] While the majority of the functionalities of clothes lie in their physical attributes, such as their softness, breathability, air/ vapor permeability, and, of course the appearance, their role in thermal management is equally, if not more, important. The primary goal of clothing is to satisfy human being’s basic needs in thermal comfort, by providing cooling in the hot environment or heating in the cold environment.[1] The energy management aspect of clothing is becoming an increasingly important and attractive aspect due to our increasing awareness to energy consumption and our persisting pursuit of comfort and health. The finite availability and the associated environmental consequence of fossil fuels have motivated us to save energy from virtually all aspects of our daily lives. A suitable thermal envelop is a necessity for our living and working. To create a comfortable indoor environment, the building heating, ventilation, and air conditioning (HVAC) systems are widely used for space cooling and heating at the expense of excessive energy consumption.[3–6] According to United States In this decade, the demands of energy saving and diverse personal thermoregulation requirements along with the emergence of wearable electronics and smart textiles give rise to the resurgence of personal thermal management (PTM) technologies. PTM, including personal cooling, heating, insulation, and thermoregulation, are far more flexible and extensive than the traditional air/liquid cooling garments for the human body. Concomitantly, many new advanced materials and strategies have emerged in this decade, promoting the thermoregulation performance and the wearing comfort of PTM simultaneously. In this review, an overview is presented of the state-ofthe-art and the prospects in this burgeoning field. The emerging materials and strategies of PTM are introduced, and classed by their thermal functions. The concept of infrared-transparent visible-opaque fabric (ITVOF) is first highlighted, as it triggers the work on advanced PTM by combining it with radiative cooling, and the corresponding implementations and realizations are subsequently introduced, followed by wearable heaters, flexible thermoelectric devices, and sweat-management Janus textiles. Finally, critical considerations on the challenges and opportunities of PTM are presented and future directions are identified, including thermally conductive polymers and fibers, physiological/psychological statistical analysis, and smart PTM strategies.

Emerging Materials and Strategies for Personal Thermal Management

Excessive sweat secreted from the skin often causes undesired adhesion from wetted textiles and cold sensations. Traditional hydrophilic textiles such as cotton can absorb sweat but retain it. A hydrophobic/superhydrophilic Janus polyester/nitrocellulose textile embedded with a conical micropore array with a hydrophilic inner surface that can achieve directional liquid transport (with an ultrahigh directional water transport capability of 1246%) and maintain human body temperature (2-3 °C higher than with cotton textiles) is demonstrated. When the hydrophobic polyester layer with large opening of hydrophilic conical micropores contacts the liquid, the Janus polyester/nitrocellulose textile can pump it to the superhydrophilic nitrocellulose layer through the hydrophilic conical micropores driven by capillary force. The Janus polyester/nitrocellulose textile can weaken undesired wet adhesion and heat loss due to the removal of liquid. The water wicking and air permeability of the Janus polyester/nitrocellulose textile is comparable to those of traditional cloths. This study is valuable for designing of functional textiles with directional water transport properties for personal drying and warming applications.

Bioinspired Janus Textile with Conical Micropores for Human Body Moisture and Thermal Management

The purpose of this paper is to provide a source of information on thermal energy use in buildings, its drivers, and their past, present and future trends on a global and regional basis. Energy use in buildings forms a large part of global and regional energy demand. The importance of heating and cooling in total building energy use is very diverse with this share varying between 18% and 73%. Biomass is still far the dominant fuel when a global picture is considered; the role of electricity is substantially growing, and the direct use of coal is disappearing from this sector, largely replaced by electricity and natural gas in the most developed regions. This paper identifies the different drivers of heating and cooling energy demand, and decomposes this energy demand into key drivers based on a Kaya identity approach: number of households, persons per household, floor space per capita and specific energy consumption for residential heating and cooling; and GDP, floor space per GDP, and specific energy consumption for commercial buildings. This paper also reviews the trends in the development of these drivers for the present, future – and for which data were available, for the past – in 11 world regions as well as globally. Results show that in a business-as-usual scenario, total residential heating and cooling energy use is expected to more or less stagnate, or slightly decrease, in the developed parts of the world. In contrast, commercial heating and cooling energy use will grow in each world region. Finally, the results show that per capita total final residential building energy use has been stagnating in the vast majority of world regions for the past three decades, despite the very significant increases in energy service levels in each of these regions.

Heating and cooling energy trends and drivers in buildings

Thermal camouflaging metamaterials

The advent of soft robotics has led to great advancements in robots, wearables, and even manufacturing processes by employing entirely soft-bodied systems that interact safely with any random surfaces while providing great mechanical compliance. Moreover, recent developments in soft robotics involve advances in transparent soft actuators and sensors that have made it possible to construct robots that can function in a visually and mechanically unobstructed manner, assisting the operations of robots and creating more applications in various fields. In this aspect, imperceptible soft robotics that mainly consist of optically transparent imperceptible hardware components is expected to constitute a new research focus in the forthcoming era of soft robotics. Here, the recent progress regarding extended imperceptible soft robotics is provided, including imperceptible transparent soft robotics (transparent soft actuators/sensors) and imperceptible nontransparent camouflage skins. Their principles, materials selections, and working mechanisms are discussed so that key challenges and perspectives in imperceptible soft robotic systems can be explored.

Transparent Soft Actuators/Sensors and Camouflage Skins for Imperceptible Soft Robotics.

Effective thermal management is critical for the operation of many modern technologies, such as electronic circuits, smart clothing, and building environment control systems. By leveraging the static infrared-reflecting design of the space blanket and drawing inspiration from the dynamic color-changing ability of squid skin, we have developed a composite material with tunable thermoregulatory properties. Our material demonstrates an on/off switching ratio of ~25 for the transmittance, regulates a heat flux of ~36 W/m2 with an estimated mechanical power input of ~3 W/m2, and features a dynamic environmental setpoint temperature window of ~8 °C. Moreover, the composite can manage one fourth of the metabolic heat flux expected for a sedentary individual and can also modulate localized changes in a wearer's body temperature by nearly 10-fold. Due to such functionality and associated figures of merit, our material may substantially reduce building energy consumption upon widespread deployment and adoption.

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A dynamic thermoregulatory material inspired by squid skin.

Soft, mechanically deformable materials and systems that can, on demand, manipulate light propagation within both the visible and infrared (IR) regions of the electromagnetic spectrum are desirable for applications that include sensing, optoelectronics, robotics, energy conservation, and thermal management. However, the development of such technologies remains exceptionally difficult, with relatively few examples reported to date. Herein, this challenge is addressed by engineering cephalopod-inspired adaptive camouflage platforms with multispectral functionality. First, stretchable copolymer membranes that feature outstanding unstrained protonic conductivities of up to ≈90 mS cm-1 , demonstrate increases of ≈80% in their conductivities at strains of 200%, and exhibit no loss in electrical performance even under extreme elongations of 500% are described. Next, the membranes are used for the fabrication of mechanically and electrically actuated camouflage devices that function over an unprecedented spectral window; can simultaneously modulate their visible and IR specular-to-diffuse transmittance ratios by >3000-fold and >4-fold, respectively; feature rapid response times of ≈0.6 s; and exhibit good performance after repeated actuation. These findings may afford new scientific and technological opportunities not only for adaptive optics and photonics but also for any platform that can benefit from simultaneously controlling visible light and heat.

Melvin Colorado Escobar

Papers

A dynamic thermoregulatory material inspired by squid skin.

Stretchable Cephalopod-Inspired Multimodal Camouflage Systems.