As wearable technologies continue to expand into healthcare and personal wellness, researchers are exploring materials that can store, convert and release heat while remaining compatible with the mechanical and comfort requirements of the human body. A new review published in Smart Materials and Devices , "Photothermal phase change materials for wearable thermal management and intelligent healthcare", examines the emerging role of photothermal phase-change materials (PCMs) in wearable thermal management and intelligent healthcare.
Photothermal PCMs have evolved beyond their traditional role as passive thermal-energy storage materials. The review describes how combining phase-change behavior with photothermal conversion, electrothermal heating, radiative heat exchange, skin-interfacing mechanics and sensing functions could provide new approaches to controlling heat in wearable systems.
For wearable applications, however, thermal storage capacity alone is not sufficient. Materials must operate within appropriate temperature ranges while maintaining softness, breathability, flexibility, durability and compatibility with prolonged skin contact. They may also need to withstand repeated bending and stretching, washing, sweat, humidity and fluctuating solar, electrical and body-heat inputs.
From thermal storage to multifunctional wearable systems
The review highlights several emerging directions for photothermal PCMs, including personal thermal management, wearable thermotherapy and intelligent healthcare.
One important design consideration is matching the phase-transition temperature to the intended application. For personal thermal comfort, this means considering the skin–clothing microclimate, while wearable thermotherapy requires higher but safe operating temperatures.
The authors emphasize that these properties must be optimized together. Increasing PCM loading may improve thermal buffering but can compromise mechanical strength and breathability, while increasing photothermal filler content can enhance heating performance but may reduce latent heat or increase stiffness.
The review therefore argues for evaluating photothermal PCMs as integrated wearable systems, rather than optimizing thermal storage properties in isolation.
Toward all-day and more adaptive thermal regulation
Another promising direction is the integration of PCMs with other thermal and energy-management technologies.
The review discusses the potential of combining PCMs with radiative cooling, electrothermal heaters, thermoelectric generators, photovoltaic or triboelectric energy harvesters to create multimodal systems capable of responding to changing environmental and operating conditions.
The authors identify Janus multimode thermal-management structures, PCM-assisted wearable thermoelectric devices and self-powered PCM-based sensors as promising areas for future research.
The review also highlights PC-Azo and molecular solar thermal (MOST) systems, which can store solar energy through photoisomerization and release heat when required. While these systems offer possibilities for lightweight, rechargeable and programmable thermal management, challenges remain in areas including visible-light response, cycling lifetime, molecular fatigue, synthesis cost and large-scale textile processing.
Another emerging direction is epidermal phase-change hydrogels, which could combine thermal buffering, adhesion, sensing and therapeutic heating within skin-interfacing platforms.
AI-guided design and real-world evaluation
The authors emphasize that the next stage of development will require more than improving material-level thermal properties.
A major challenge is the lack of standardized evaluation methods that reproduce real wearing conditions. Future testing should consider not only phase-transition temperature, latent heat and photothermal conversion efficiency, but also stretching and bending fatigue, abrasion, washing durability, sweat and skin-oil resistance, air permeability, water-vapor transmission, skin compatibility and long-term thermal performance.
The review also points to data-driven and AI-guided design as a potential way to accelerate material and device optimization. Machine-learning approaches could eventually help screen candidate PCM molecules, optimize photothermal filler formulations, predict heat-flow pathways in multilayer wearable structures and balance competing properties such as thermal storage, stretchability, breathability, durability and skin comfort.
Looking ahead
The review concludes that future progress in wearable photothermal PCMs is likely to come from the integration of phase-change materials, multimodal thermal regulation, wearable energy harvesting, skin-interfacing systems and data-driven design.
Rather than focusing solely on maximizing latent heat, the field is moving toward system-level materials and devices that balance thermal performance with wearability, durability and human–material compatibility.
