Self-regulated bidirectional temperature gradients in radiation-modulated fabrics for diurnal thermal comfort management and energy harvesting

Harvesting low-grade heat from both human metabolism and environmental waste through thermoelectric fabrics offers a sustainable pathway for wearable power generation. However, a critical challenge exists in establishing substantial temperature differentials for continuous thermoelectric generation while maintaining physiologically comfortable skin temperatures in dynamically variable environments.

A team of material scientists led by Xiao-Qiao Wang from Soochow University, China, recently presented a dynamic radiation-modulated sandwich-structured fabric capable of diurnally adaptive operation that simultaneously enables thermal comfort regulation and thermoelectric energy harvesting. Based on a parallel dual-spinneret blow-spinning technique, the research team developed all-fibrous thermoelectric fabrics featuring asymmetric electrodes. The optimized sandwich fabric demonstrates significant bidirectional temperature gradients under both daytime and nighttime conditions while maintaining skin-contact temperatures within the physiological comfort zone. Theoretical and experimental analyses indicate that these self-regulated thermal gradients originate from the asymmetric optical properties between the top and bottom layers. This effect is further enhanced by a hierarchical porous fibrous interlayer that confines thermal transfer. Outdoor testing confirmed the fabric’s stable diurnal performance for both thermal comfort management and energy harvesting. Through modular integration, the system successfully generates usable electrical output.

The team published their research in Nano Research on February 4, 2026.

“In this work, we propose a dynamic radiation-modulated fabric that enables diurnally adaptive dual-mode thermal management and energy harvesting. The fabric generates self-regulated bidirectional temperature gradients, adapting to varying solar irradiance and ambient temperatures in diurnal cycles, enabling environmentally adaptive thermal management,” said Ke-Qin Zhang, the author of this research paper, Distinguished Professor at the College of Textile and Clothing Engineering of Soochow University. Prof. Zhang also serves as the Dean of the College of Textile and Clothing Engineering.

The research team outlines the schematic structure of sandwich fabrics and their dynamic dual-mode radiative thermoregulation mechanism. “The sandwich fabric demonstrates diurnally adaptive radiation modulation to establish bidirectional ΔT between the two electrode layers. When exposed to solar irradiation during the daytime, the temperature of the MWCNT side rapidly increases due to its high solar absorption property, and the enhanced positive ΔT between the MWCNT and AgNW sides leads to direct conversion of solar thermal energy into electricity. Notably, confined heat transfer within the interpenetrating pores of PAN/SWCNT interlayer significantly suppresses through-thickness thermal conduction, preserving high positive ΔT for thermoelectric generation under fluctuating sunlight while keeping the skin-contact surface (AgNW side) temperature within the comfort zone. Under cold nighttime conditions, the low mid-infrared emissivity of AgNWs, coupled with the low thermal conduction of PAN/SWCNT interlayer, effectively minimizes the human body heat loss, maintaining the skin-contact surface temperature within the physiological comfort range. Meanwhile, the high mid-infrared emissivity of MWCNTs enables sub-ambient cooling on the outermost side via nighttime radiative cooling effect. This delicate structure maximizes a negative ΔT between the MWCNT and AgNW sides, facilitating continuous thermoelectric power generation at night,” Ke-Qin Zhang said.

The thermoelectric performance of MWCNT-PAN/SWCNT-AgNW sandwich fabrics is fundamentally governed by the PAN/SWCNT interlayer, which requires simultaneous high porosity and electrical conductivity. Conventional blend electrospinning of PAN/SWCNT composite nanofibers suffers from inherent conductivity limitations, as the insulating PAN matrix typically encapsulates dispersed SWCNTs, disrupting percolation pathways. To overcome this, Wang’s team developed a parallel dual-spinneret blow-spinning technique that enables surface-localized deposition of SWCNTs on PAN nanofibers via aerodynamic assistance and in situ formation of interconnected conductive networks while preserving structural porosity.

The research team developed a custom parallel dual-coaxial spinneret for co-spraying SWCNT dispersions and PAN solutions. “Under high-speed airflow, both solutions were co-extruded, with PAN solidifying into continuous nanofibers through polymer chain stretching and rapid solvent evaporation. Simultaneously, aerodynamic forces enabled uniform dispersion and surface deposition of SWCNTs onto the forming nanofibers. This process facilitated in situ assembly of SWCNTs into percolated conductive networks on nanofiber surfaces, creating continuous electron transport pathways. The resulting PAN/SWCNT composite nanofibrous membranes demonstrated p-type thermoelectric behavior, achieving a maximum Seebeck coefficient of 54.4 μV·K^-1,” Ke-Qin Zhang said.

The research team also did thermodynamic analysis and temperature gradient simulations. The temperature curves from both simulation and experiment show a good agreement. The marginally steeper experimental profiles likely originate from structural inhomogeneity in the nanofibrous composites. The optimal ΔT of the sandwich fabric is about 9.5 °C and -8 °C during the day and night, respectively.

To evaluate practical applicability, the research team conducted continuous outdoor monitoring of the MWCNT-PAN/SWCNT-AgNW sandwiched fabric’s temperature and output voltage. “The output voltage closely follows the variation in solar irradiance, reaching a maximum of 0.3 mV at noon. Remarkably, the sandwich fabric maintained continuous electricity generation for over 72 hours. Benefiting from its dynamic radiation-modulated bidirectional temperature gradients, the sandwich fabric exhibits continuous thermal comfort management and sustainable energy harvesting, adapting to diurnal cycles,” Ke-Qin Zhang said. 

Through modular integration, the sandwich fabric achieves significantly enhanced voltage output, with outdoor testing demonstrating a peak voltage of 20 mV under practical operating conditions. By synergistically combining adaptive thermal regulation with thermoelectric generation via dynamic radiation-modulated bidirectional temperature gradients, this work overcomes the dual-functional challenges of energy harvesting and personal comfort management, enabling next-generation smart textiles for practical thermal energy management and utilization.

Other contributors include An-Quan Xie, Wangkai Jiang, Hui Qiu, Xin-Long Qian, Xiao-Qiao Wang from the College of Textile and Clothing Engineering of Soochow University, China; and Ghim Wei Ho from the Department of Electrical and Computer Engineering, National University of Singapore, Singapore.

This work was supported by the National Natural Science Foundation of China (Grant Nos. 22308236, 52303321), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (23KJA430012), the Natural Science Foundation of Jiangsu Province, China (BK20230501), the Leading Talents of Innovation and Entrepreneurship of Gusu (ZXL2024370), the China Postdoctoral Science Foundation (Grant Nos. 2024T170632, 2024M752348, 2024T170623, and 2023M742530).

DOI Link:

https://doi.org/10.26599/NR.2025.94908271

About Nano Research

Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.