Kirigami-processed cellulose nanofiber films for smart heat dissipation by convection

Heat dissipation has become increasingly important in electronics. Conventional convection cooling systems have significant material and dimensional constraints, and they have difficulty meeting the heat dissipation, miniaturization, and flexibility requirements of next-generation smart electronics. Here, we used kirigami (the traditional art of paper cutting) with a thermally conductive cellulose nanofiber film to propose a flexible cooling system through convective heat dissipation. By stretching the Amikazari (net decoration) pattern produced by kirigami and allowing air convection through its aperture at 3.0 m/s, the thermal resistance was reduced to approximately one-fifth of that without kirigami and convection. The kirigami apertures defined the outlet air velocity, resulting in a significant increase in the heat-transfer coefficient. Our kirigami heat dissipation concept enables the design of electronics using a variety of film materials as shape-variant cooling structures, which will inspire a wide range of thermal engineering and electronics applications. A shape-variant heat dissipation system using kirigami was proposed using the thermally conductive cellulose nanofiber films. By stretching the Amikazari (net decoration) pattern produced by kirigami and allowing air convection through its aperture at 3.0m/s, the thermal resistance was reduced to approximately one-fifth of that without kirigami and convection. The periodic apertures of kirigami defined the outlet air velocity of convection, resulting in a significant increase in the heat-transfer coefficient. We further demonstrated the effective cooling of the kirigami-processed powder electroluminescent device during the emission of light.