Once China’s Tianwen-1 Mars probe arrived in a Mars orbit after a seven-month flight in the deep cold space environment,it would be urgently necessary to monitor its state and the surrounding environment.To address t...Once China’s Tianwen-1 Mars probe arrived in a Mars orbit after a seven-month flight in the deep cold space environment,it would be urgently necessary to monitor its state and the surrounding environment.To address this issue,we developed a flexible deployable subsystem based on shape memory polymer composites(SMPC-FDS)with a large folding ratio,which incorporates a camera and two temperature telemetry points for monitoring the local state of the Mars orbiter and the deep space environment.Here,we report on the development,testing,and successful application of the SMPC-FDS.Before reaching its Mars remote-sensing orbit,the SMPC-FDS is designed to be in a folded state with high stiffness;after reaching orbit,it is in a deployed state with a large envelope.The transition from the folded state to the deployed state is achieved by electrically heating the shape memory polymer composites(SMPCs);during this process,the camera on the SMPC-FDS can capture the local state of the orbiter from multiple angles.Moreover,temperature telemetry points on the SMPC-FDS provide feedback on the environment temperature and the temperature change of the SMPCs during the energization process.By simulating a Mars on-orbit space environment,the engineering reliability of the SMPC-FDS was comprehensively verified in terms of the material properties,structural dynamic performance,and thermal vacuum deployment feasibility.Since the launch of Tianwen-1 on 23 July 2020,scientific data on the temperature environment around Tianwen-1 has been successfully acquired from the telemetry points on the SMPCFDS,and the local state of the orbiter has been photographed in orbit,showing the national flag of China fixed on the orbiter.展开更多
The emergence of additive manufacturing(AM)enables ceramics to be fabricated with customized geometry,and polymer-derived ceramics(PDCs)has attracted growing attention owing to their irreplaceable advantages.The combi...The emergence of additive manufacturing(AM)enables ceramics to be fabricated with customized geometry,and polymer-derived ceramics(PDCs)has attracted growing attention owing to their irreplaceable advantages.The combination of 3D printing and PDCs endows the resultant ceramics with both precision and performance.However,AM of ceramics from preceramic polymers is still challenging,and insufficient investigation of functionality also limits the versatility of precursor and its derived ceramics.Herein,we propose a novel paradigm for 3D printing dense silicon carbonitride ceramic and study its electrical semiconducting properties.The formulated photosensitive precursor inks could achieve self-polymerization and cross-linking under the radiation of UV light(405 nm).The green body with intricate structures is fabricated by digital light processing(DLP).Lightweight(1.79-2.08 g cm^(-3))and low porosity(<5%)amorphous ceramics were obtained after thermal treatments.Processes of cross-linking,decomposition,and ceramization are monitored and analyzed.Furthermore,the semi-conducting behaviors of resultant ceramics are identified where the conductivity(10^(-5)-10^(-1)S m^(-1))has a monotonic correspondence with the testing temperatures(25-1000℃).The numerical relationship is fitted by exponential functions,and its conducting mechanism could be interpreted by the band tail hopping(BTH)model.This work could provide alternative solutions for the fabrication of PDCs and potentials for sensing applications.展开更多
Stimuli-responsive polymers offer unprecedented control over drug release in implantable delivery systems.Shape memorypolymer fibers(SMPFs),with their large specific surface area and programmable properties,present pr...Stimuli-responsive polymers offer unprecedented control over drug release in implantable delivery systems.Shape memorypolymer fibers(SMPFs),with their large specific surface area and programmable properties,present promising alternativesfor triggerable drug delivery.However,the existing SMPFs face limitations in resolution,architecture,scalability,and functionality.We introduce thermal drawing as a materials and processing platform to fabricate microstructured,multimaterialSMPFs that are tens of meters long,with high resolution(10μm)and extreme aspect ratios(>105).These novel fibersachieve highly controlled,sequential drug release over tailored time periods of 6 months.Post thermal drawing photothermalcoatings enable accelerated,spatially precise drug release within 4 months and facilitate light-triggered,untethered shaperecovery.The fibers’fast self-tightening capability within 40 s shows their potential as smart sutures for minimally invasiveprocedures that deliver drugs simultaneously.In addition,the advanced multimaterial platform facilitates the integrationof optical and metallic elements within SMP systems,allowing highly integrated fibers with shape memory attributes andunprecedented functionalities.This versatile technology opens new avenues for diverse biomedical applications,includingimplantable drug delivery systems,smart sutures,wound dressings,stents,and functional textiles.It represents a significantadvancement in precise spatio-temporal control of drug delivery and adaptive medical devices.展开更多
基金supported by the National Natural Science Foundation of China(11632005)the Heilongjiang Touyan Innovation Team Program。
文摘Once China’s Tianwen-1 Mars probe arrived in a Mars orbit after a seven-month flight in the deep cold space environment,it would be urgently necessary to monitor its state and the surrounding environment.To address this issue,we developed a flexible deployable subsystem based on shape memory polymer composites(SMPC-FDS)with a large folding ratio,which incorporates a camera and two temperature telemetry points for monitoring the local state of the Mars orbiter and the deep space environment.Here,we report on the development,testing,and successful application of the SMPC-FDS.Before reaching its Mars remote-sensing orbit,the SMPC-FDS is designed to be in a folded state with high stiffness;after reaching orbit,it is in a deployed state with a large envelope.The transition from the folded state to the deployed state is achieved by electrically heating the shape memory polymer composites(SMPCs);during this process,the camera on the SMPC-FDS can capture the local state of the orbiter from multiple angles.Moreover,temperature telemetry points on the SMPC-FDS provide feedback on the environment temperature and the temperature change of the SMPCs during the energization process.By simulating a Mars on-orbit space environment,the engineering reliability of the SMPC-FDS was comprehensively verified in terms of the material properties,structural dynamic performance,and thermal vacuum deployment feasibility.Since the launch of Tianwen-1 on 23 July 2020,scientific data on the temperature environment around Tianwen-1 has been successfully acquired from the telemetry points on the SMPCFDS,and the local state of the orbiter has been photographed in orbit,showing the national flag of China fixed on the orbiter.
基金the National Natural Science Foundation of China(No.12090034).
文摘The emergence of additive manufacturing(AM)enables ceramics to be fabricated with customized geometry,and polymer-derived ceramics(PDCs)has attracted growing attention owing to their irreplaceable advantages.The combination of 3D printing and PDCs endows the resultant ceramics with both precision and performance.However,AM of ceramics from preceramic polymers is still challenging,and insufficient investigation of functionality also limits the versatility of precursor and its derived ceramics.Herein,we propose a novel paradigm for 3D printing dense silicon carbonitride ceramic and study its electrical semiconducting properties.The formulated photosensitive precursor inks could achieve self-polymerization and cross-linking under the radiation of UV light(405 nm).The green body with intricate structures is fabricated by digital light processing(DLP).Lightweight(1.79-2.08 g cm^(-3))and low porosity(<5%)amorphous ceramics were obtained after thermal treatments.Processes of cross-linking,decomposition,and ceramization are monitored and analyzed.Furthermore,the semi-conducting behaviors of resultant ceramics are identified where the conductivity(10^(-5)-10^(-1)S m^(-1))has a monotonic correspondence with the testing temperatures(25-1000℃).The numerical relationship is fitted by exponential functions,and its conducting mechanism could be interpreted by the band tail hopping(BTH)model.This work could provide alternative solutions for the fabrication of PDCs and potentials for sensing applications.
基金the Swiss National Science Foundation(SNSF project 200021_204579)The authors thank Dr.Shahrzad Shadman,Dr.Bastien Schyrr,Dr.Ines Richard,Dr.Andreas Leber,and Dr.Dong Yan for conducive discussion and experimental support+1 种基金the Laboratory for Processing of Advanced Composites(LPAC)at EPFL for the support in terms of equipment usagethe support from the China Scholarship Council.
文摘Stimuli-responsive polymers offer unprecedented control over drug release in implantable delivery systems.Shape memorypolymer fibers(SMPFs),with their large specific surface area and programmable properties,present promising alternativesfor triggerable drug delivery.However,the existing SMPFs face limitations in resolution,architecture,scalability,and functionality.We introduce thermal drawing as a materials and processing platform to fabricate microstructured,multimaterialSMPFs that are tens of meters long,with high resolution(10μm)and extreme aspect ratios(>105).These novel fibersachieve highly controlled,sequential drug release over tailored time periods of 6 months.Post thermal drawing photothermalcoatings enable accelerated,spatially precise drug release within 4 months and facilitate light-triggered,untethered shaperecovery.The fibers’fast self-tightening capability within 40 s shows their potential as smart sutures for minimally invasiveprocedures that deliver drugs simultaneously.In addition,the advanced multimaterial platform facilitates the integrationof optical and metallic elements within SMP systems,allowing highly integrated fibers with shape memory attributes andunprecedented functionalities.This versatile technology opens new avenues for diverse biomedical applications,includingimplantable drug delivery systems,smart sutures,wound dressings,stents,and functional textiles.It represents a significantadvancement in precise spatio-temporal control of drug delivery and adaptive medical devices.
