Numerous scenarios of direct contact between electronic components and skin appear in wearable electronic devices. As the “second skin” that lies next to the biological skin of the human body, flexible wearable devi...Numerous scenarios of direct contact between electronic components and skin appear in wearable electronic devices. As the “second skin” that lies next to the biological skin of the human body, flexible wearable devices need to be equipped with thermal protection. However, the use of flexible phase change materials(PCMs) for wearable devices remains a challenge due to their low thermal conductivity, weakened mechanical strength, and liquid leakage. Herein, we developed a multilayered polyimide(PI) composite film integrating stable latent heat absorption, high thermal conductivity, and enhanced mechanical strength. This single piece of material achieved more prominent hotspot protection than traditional foams. The in-plane thermal conductivity of the resultant substrate layer is up to 2.655 W/(m K), which provides a fast response and in-plane dissipation for heat flow. The deliberately arranged interlayer of the material significantly improved the tensile strength(37.6 MPa) of the composite film,representing 128.9% greater strength than that of a bilayer film without a dense layer. The top layer with abundant pores provides reversibly latent heat storing and releasing function after being well infiltrated with paraffin wax. The resulting synergistic effect between three functional layers shows superb heat-suppressing performance in the thickness direction in both thermal shockresistant tests and simulation results. Impressively, the maximum temperature drop reached 40.2℃ compared with the pure PI film. The heating time was delayed by 12 s, providing sufficient warning time for human emergency response. This strategy can potentially pave the way for the design and fabrication of multifunctional films for wearable electronics in thermal protection applications.展开更多
In hot environments,the human body shows an efficient capability to maintain a stable temperature by benefiting from sweating behavior.Inspired by this skin perspiration strategy,in this study,we demonstrated an innov...In hot environments,the human body shows an efficient capability to maintain a stable temperature by benefiting from sweating behavior.Inspired by this skin perspiration strategy,in this study,we demonstrated an innovative polyimide foam(PIF)-based mimetic skin with excellent cooling capability by integrating a silver coating and reusable hydrogel for the first time.Because of the hybrid thermal dissipating system,the successive silver coating quickly transferred heat to the inside of the polyacrylamide hydrogel.Meanwhile,the hydrogel absorbed a large amount of heat due to its large enthalpy and effectively dissipated heat to the environment through the evaporation of moisture,similar to the sweating of skin.Thus,the temperature of the skin-like film was reduced by 25.4℃compared with pure PIF under a high-power laser heating source.Identical and remarkable cooling effects were also obtained in mobile phone and battery applications,far better than commercially available thermally conductive polyimide(PI).This outstanding performance paves a new way for the thermal management application of PI in wearable electronics,microprocessors,and flexible electronics.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.U21A2094)the CASHIPS Director's Fund(Grant No.YZJJZX202015)。
文摘Numerous scenarios of direct contact between electronic components and skin appear in wearable electronic devices. As the “second skin” that lies next to the biological skin of the human body, flexible wearable devices need to be equipped with thermal protection. However, the use of flexible phase change materials(PCMs) for wearable devices remains a challenge due to their low thermal conductivity, weakened mechanical strength, and liquid leakage. Herein, we developed a multilayered polyimide(PI) composite film integrating stable latent heat absorption, high thermal conductivity, and enhanced mechanical strength. This single piece of material achieved more prominent hotspot protection than traditional foams. The in-plane thermal conductivity of the resultant substrate layer is up to 2.655 W/(m K), which provides a fast response and in-plane dissipation for heat flow. The deliberately arranged interlayer of the material significantly improved the tensile strength(37.6 MPa) of the composite film,representing 128.9% greater strength than that of a bilayer film without a dense layer. The top layer with abundant pores provides reversibly latent heat storing and releasing function after being well infiltrated with paraffin wax. The resulting synergistic effect between three functional layers shows superb heat-suppressing performance in the thickness direction in both thermal shockresistant tests and simulation results. Impressively, the maximum temperature drop reached 40.2℃ compared with the pure PI film. The heating time was delayed by 12 s, providing sufficient warning time for human emergency response. This strategy can potentially pave the way for the design and fabrication of multifunctional films for wearable electronics in thermal protection applications.
基金the National Natural Science Foundation of China(Grant No.U21A2094)CASHIPS Director's Fund(Grant Nos.YZJJZX202015,YZJJ202304-CX,and YZJJ2023QN36)the Anhui Province Postdoctoral Researcher Research Project(Grant No.E24F0D27)。
文摘In hot environments,the human body shows an efficient capability to maintain a stable temperature by benefiting from sweating behavior.Inspired by this skin perspiration strategy,in this study,we demonstrated an innovative polyimide foam(PIF)-based mimetic skin with excellent cooling capability by integrating a silver coating and reusable hydrogel for the first time.Because of the hybrid thermal dissipating system,the successive silver coating quickly transferred heat to the inside of the polyacrylamide hydrogel.Meanwhile,the hydrogel absorbed a large amount of heat due to its large enthalpy and effectively dissipated heat to the environment through the evaporation of moisture,similar to the sweating of skin.Thus,the temperature of the skin-like film was reduced by 25.4℃compared with pure PIF under a high-power laser heating source.Identical and remarkable cooling effects were also obtained in mobile phone and battery applications,far better than commercially available thermally conductive polyimide(PI).This outstanding performance paves a new way for the thermal management application of PI in wearable electronics,microprocessors,and flexible electronics.
