Objective:To investigate the differences between meditation and resting states using infrared thermal imaging(IRTI)to determine facial temperature distribution features during meditation and annotate the patterns of f...Objective:To investigate the differences between meditation and resting states using infrared thermal imaging(IRTI)to determine facial temperature distribution features during meditation and annotate the patterns of facial temperature changes during meditation from the perspective of traditional Chinese medicine facial diagnosis.Methods:Each participant performed 10 min meditation and 10 min resting but in different sequences.A concentration test was set as the task load,followed by a meditation/resting or resting/meditation session,during which the participants'facial temperatures were observed using IRTI.Participants were scored on the Big Five Inventory(BFI)and Mindful Attention Awareness Scale(MAAS).Results:Forehead temperatures decreased more during meditation than during the resting state.The chin temperature increased only during meditation(P<.0001).For the subjects with meditation experience,there were significant differences in the temperatures of the left forehead(P<.01),right forehead(P<.01)and chin(P<.05)between the meditation and resting state at the 10~(th)min.In the nontask state,the BFI-Extraversion showed a negative correlation with the temperature of the left forehead(R=-0.41,P=.03).In the post-task state,the temperature of the left forehead was negatively correlated with scores on the MAAS(R=-0.42,P=.02).Conclusion:Using IRTI to study meditation offers a practical solution to the challenges in meditation research.The results indicate that an increase in chin temperature may be a representative feature of a meditation state,and forehead temperature is also a potential indicator.展开更多
Shape sensing as a crucial component of structural health monitoring plays a vital role in real-time actuation and control of smart structures,and monitoring of structural integrity.As a model-based method,the inverse...Shape sensing as a crucial component of structural health monitoring plays a vital role in real-time actuation and control of smart structures,and monitoring of structural integrity.As a model-based method,the inverse finite element method(iFEM)has been proved to be a valuable shape sensing tool that is suitable for complex structures.In this paper,we propose a novel approach for the shape sensing of thin shell structures with iFEM.Considering the structural form and stress characteristics of thin-walled structure,the error function consists of membrane and bending section strains only which is consistent with the Kirchhoff–Love shell theory.For numerical implementation,a new four-node quadrilateral inverse-shell element,iDKQ4,is developed by utilizing the kinematics of the classical shell theory.This new element includes hierarchical drilling rotation degrees-of-freedom(DOF)which enhance applicability to complex structures.Firstly,the reconstruction performance is examined numerically using a cantilever plate model.Following the validation cases,the applicability of the iDKQ4 element to more complex structures is demonstrated by the analysis of a thin wallpanel.Finally,the deformation of a typical aerospace thin-wall structure(the composite tank)is reconstructed with sparse strain data with the help of iDKQ4 element.展开更多
Highly sensitive broadband photodetection is of critical importance for many applications.However,it is a great challenge to realize broadband photodetection by using a single device.Here we report photodetectors(PDs)...Highly sensitive broadband photodetection is of critical importance for many applications.However,it is a great challenge to realize broadband photodetection by using a single device.Here we report photodetectors(PDs)based on three-dimensional(3 D)graphene foam(GF)photodiodes with asymmetric electrodes,which show an ultra-broadband photoresponse from ultraviolet to microwave for wavelengths ranging from 10~2 to 10~6 nm.Moreover,the devices exhibit a high photoresponsivity of 10~3 A·W^-1,short response time of 43 ms,and3 d B bandwidth of 80 Hz.The high performance of the devices can be attributed to the photothermoelectric(PTE,also known as the Seebeck)effect in 3 D GF photodiodes.The excellent optical,thermal,and electrical properties of 3 D GFs offer a superior basis for the fabrication of PTE-based PDs.This work paves the way to realize ultra-broadband and high-sensitivity PDs operated at room temperature.展开更多
Self-powered and flexible ultrabroadband photodetectors(PDs)are desirable in a wide range of applications.The current PDs based on the photothermoelectric(PTE)effect have realized broadband photodetection.However,most...Self-powered and flexible ultrabroadband photodetectors(PDs)are desirable in a wide range of applications.The current PDs based on the photothermoelectric(PTE)effect have realized broadband photodetection.However,most of them express low photoresponse and lack of flexibility.In this work,high-performance,self-powered,and flexible PTE PDs based on laser-scribed reduced graphene oxide(LSG)∕CsPbBr3 are developed.The comparison experiment with LSG PD and fundamental electric properties show that the LSG∕CsPbBr3 device exhibits enhanced ultrabroadband photodetection performance covering ultraviolet to terahertz range with high photoresponsivity of 100 mA/W for 405 nm and 10 mA/W for 118μm at zero bias voltage,respectively.A response time of 18 ms and flexible experiment are also acquired at room temperature.Moreover,the PTE effect is fully discussed in the LSG∕CsPbBr3 device.This work demonstrates that LSG∕CsPbBr3 is a promising candidate for the construction of high-performance,flexible,and self-powered ultrabroadband PDs at room temperature.展开更多
Biosensors are a focus of research on terahertz metasurfaces. However, reports of ultra-sensitive biosensors based on Dirac points are rare. Here, a new terahertz metasurface is proposed that consists of patterned gra...Biosensors are a focus of research on terahertz metasurfaces. However, reports of ultra-sensitive biosensors based on Dirac points are rare. Here, a new terahertz metasurface is proposed that consists of patterned graphene and perovskites. This serves as an ultra-sensitive Dirac-point-based biosensor for qualitative detection of sericin.Theoretically, sericin may make graphene n-doped and drive the Fermi level to shift from the valence band to the Dirac point, causing a dramatic decrease in conductivity. Correspondingly, the dielectric environment on the metasurface undergoes significant change, which is suited for ultra-sensitive biosensing. In addition, metal halide perovskites, which are up-to-date optoelectronic materials, have a positive effect on the phase during terahertz wave transmission. Thus, this sensor was used to successfully detect sericin with a detection limit of 780 pg/m L, achieved by changing the amplitude and phase. The detection limit of this sensor is as much as one order of magnitude lower than that of sensors in published works. These results show that the Dirac-pointbased biosensor is a promising platform for a wide range of ultra-sensitive and qualitative detection in biosensing and biological sciences.展开更多
The preparation of high-quality perovskite films with optimal morphologies is important for achieving highperformance perovskite photodetectors(PPDs). An effective strategy to optimize the morphologies is to add antis...The preparation of high-quality perovskite films with optimal morphologies is important for achieving highperformance perovskite photodetectors(PPDs). An effective strategy to optimize the morphologies is to add antisolvents during the spin-coating steps. In this work, a novel environment-friendly antisolvent tert-amyl alcohol(TAA) is employed first to improve the quality of perovskite films, which can effectively regulate the formation of an intermediate phase staged in between a liquid precursor phase and a solid perovskite phase due to its moderate polarity and further promote the homogeneous nucleation and crystal growth, thus leading to the formation of high-quality perovskite films and enhanced photodetector performance. As a result, the responsivity of the PPD reaches 1.56 A/W under the illumination of 532 nm laser with the power density of 6.37 μW=cm^(2) at a bias voltage of -2 V, which is good responsivity for PPDs with the vertical structure and only CH_(3)NH_(3)PbI_(3) perovskite as the photosensitive material. The corresponding detectivity reaches 1.47×10^(12) Jones, while the linear dynamic range reaches 110 dB. These results demonstrate that our developed green antisolvent TAA has remarkable advantages for the fabrication of high-performance PPDs and can provide a reference for similar research work.展开更多
Active control of the electromagnetically induced transparency(EIT)analog is desirable in photonics development.Here,we theoretically and experimentally proposed a novel terahertz(THz)asymmetric metasurface structure ...Active control of the electromagnetically induced transparency(EIT)analog is desirable in photonics development.Here,we theoretically and experimentally proposed a novel terahertz(THz)asymmetric metasurface structure that can possess high-sensitivity modulation under extremely low power density by integrating perovskite or graphene.Using the novel metasurface structure with the perovskite coating,the maximum amplitude modulation depth(AMD)of this perovskite-based device reached 490.53%at a low power density of 12.8037 mW/cm^(2).In addition,after the novel THz metasurface structure was combined with graphene,this graphene-based device also achieved high AMD with the maximum AMD being 180.56%at 16.312 mW/cm^(2),and its transmission amplitude could be electrically driven at a low bias voltage.The physical origin of this modulation was explained using a two-oscillator EIT model.This work provides a promising platform for developing high-sensitivity THz sensors,light modulators,and switches.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(x2021-JYB-XJSJJ-032)Beijing Municipal Commission of Education,Double First-class,High-caliber Talents Grant(1000041510156)。
文摘Objective:To investigate the differences between meditation and resting states using infrared thermal imaging(IRTI)to determine facial temperature distribution features during meditation and annotate the patterns of facial temperature changes during meditation from the perspective of traditional Chinese medicine facial diagnosis.Methods:Each participant performed 10 min meditation and 10 min resting but in different sequences.A concentration test was set as the task load,followed by a meditation/resting or resting/meditation session,during which the participants'facial temperatures were observed using IRTI.Participants were scored on the Big Five Inventory(BFI)and Mindful Attention Awareness Scale(MAAS).Results:Forehead temperatures decreased more during meditation than during the resting state.The chin temperature increased only during meditation(P<.0001).For the subjects with meditation experience,there were significant differences in the temperatures of the left forehead(P<.01),right forehead(P<.01)and chin(P<.05)between the meditation and resting state at the 10~(th)min.In the nontask state,the BFI-Extraversion showed a negative correlation with the temperature of the left forehead(R=-0.41,P=.03).In the post-task state,the temperature of the left forehead was negatively correlated with scores on the MAAS(R=-0.42,P=.02).Conclusion:Using IRTI to study meditation offers a practical solution to the challenges in meditation research.The results indicate that an increase in chin temperature may be a representative feature of a meditation state,and forehead temperature is also a potential indicator.
基金The author received funding for this study from National Key R&D Program of China(2018YFA0702800)National Natural Science Foundation of China(11602048)This study is also supported by National Defense Fundamental Scientific Research Project(XXXX2018204BXXX).
文摘Shape sensing as a crucial component of structural health monitoring plays a vital role in real-time actuation and control of smart structures,and monitoring of structural integrity.As a model-based method,the inverse finite element method(iFEM)has been proved to be a valuable shape sensing tool that is suitable for complex structures.In this paper,we propose a novel approach for the shape sensing of thin shell structures with iFEM.Considering the structural form and stress characteristics of thin-walled structure,the error function consists of membrane and bending section strains only which is consistent with the Kirchhoff–Love shell theory.For numerical implementation,a new four-node quadrilateral inverse-shell element,iDKQ4,is developed by utilizing the kinematics of the classical shell theory.This new element includes hierarchical drilling rotation degrees-of-freedom(DOF)which enhance applicability to complex structures.Firstly,the reconstruction performance is examined numerically using a cantilever plate model.Following the validation cases,the applicability of the iDKQ4 element to more complex structures is demonstrated by the analysis of a thin wallpanel.Finally,the deformation of a typical aerospace thin-wall structure(the composite tank)is reconstructed with sparse strain data with the help of iDKQ4 element.
基金National Natural Science Foundation of China(61675147,61605141,61735010,91838301)National Key Research and Development Program of China(2017YFA0700202)+2 种基金Basic Research Program of Shenzhen(JCYJ20170412154447469)Beiyang Yong Junior Faculties of Tianjin University(2019XRG-0056)Wenzhou City Governmental Public Industrial Technology Project(G20160014)。
文摘Highly sensitive broadband photodetection is of critical importance for many applications.However,it is a great challenge to realize broadband photodetection by using a single device.Here we report photodetectors(PDs)based on three-dimensional(3 D)graphene foam(GF)photodiodes with asymmetric electrodes,which show an ultra-broadband photoresponse from ultraviolet to microwave for wavelengths ranging from 10~2 to 10~6 nm.Moreover,the devices exhibit a high photoresponsivity of 10~3 A·W^-1,short response time of 43 ms,and3 d B bandwidth of 80 Hz.The high performance of the devices can be attributed to the photothermoelectric(PTE,also known as the Seebeck)effect in 3 D GF photodiodes.The excellent optical,thermal,and electrical properties of 3 D GFs offer a superior basis for the fabrication of PTE-based PDs.This work paves the way to realize ultra-broadband and high-sensitivity PDs operated at room temperature.
基金National Natural Science Foundation of China(61605141,61675147,61735010,91838301)National Key Research and Development Program of China(2017YFA0700202)+1 种基金Basic Research Program of Shenzhen(JCYJ20170412154447469)Beiyang Young Junior faculties of Tianjin University(2019XRG-0056).
文摘Self-powered and flexible ultrabroadband photodetectors(PDs)are desirable in a wide range of applications.The current PDs based on the photothermoelectric(PTE)effect have realized broadband photodetection.However,most of them express low photoresponse and lack of flexibility.In this work,high-performance,self-powered,and flexible PTE PDs based on laser-scribed reduced graphene oxide(LSG)∕CsPbBr3 are developed.The comparison experiment with LSG PD and fundamental electric properties show that the LSG∕CsPbBr3 device exhibits enhanced ultrabroadband photodetection performance covering ultraviolet to terahertz range with high photoresponsivity of 100 mA/W for 405 nm and 10 mA/W for 118μm at zero bias voltage,respectively.A response time of 18 ms and flexible experiment are also acquired at room temperature.Moreover,the PTE effect is fully discussed in the LSG∕CsPbBr3 device.This work demonstrates that LSG∕CsPbBr3 is a promising candidate for the construction of high-performance,flexible,and self-powered ultrabroadband PDs at room temperature.
基金National Natural Science Foundation of China(61675147, 61701434, 61735010)Special Funding of the Taishan Scholar Project (tsqn201909150)+6 种基金Natural Science Foundation of Guangxi Province (ZR2020FK008)National Key Research and Development Program of China(2017YFA0700202, 2017YFB1401203)Qingchuang Science and Technology Plan of Shandong Universities(2019KJN001)Shandong Province Higher Education Science and Technology Program (J17KA087)Natural Science Foundation of Jiangsu Province (BK20180862)China Postdoctoral Fund (2019M651725)Natural Science Foundation of Shandong Province (ZR202102180769)。
文摘Biosensors are a focus of research on terahertz metasurfaces. However, reports of ultra-sensitive biosensors based on Dirac points are rare. Here, a new terahertz metasurface is proposed that consists of patterned graphene and perovskites. This serves as an ultra-sensitive Dirac-point-based biosensor for qualitative detection of sericin.Theoretically, sericin may make graphene n-doped and drive the Fermi level to shift from the valence band to the Dirac point, causing a dramatic decrease in conductivity. Correspondingly, the dielectric environment on the metasurface undergoes significant change, which is suited for ultra-sensitive biosensing. In addition, metal halide perovskites, which are up-to-date optoelectronic materials, have a positive effect on the phase during terahertz wave transmission. Thus, this sensor was used to successfully detect sericin with a detection limit of 780 pg/m L, achieved by changing the amplitude and phase. The detection limit of this sensor is as much as one order of magnitude lower than that of sensors in published works. These results show that the Dirac-pointbased biosensor is a promising platform for a wide range of ultra-sensitive and qualitative detection in biosensing and biological sciences.
基金National Natural Science Foundation of China(61675147,61735010,91838301)National Key Research and Development Program of China(2017YFA0700202)+3 种基金Department of Education of Guangdong Province(2018KQNCX264)Basic Research Program of Shenzhen(JCYJ20170412154447469)Beiyang Yong Junior Faculties of Tianjin University(2019XRG-0056)Wenzhou City Governmental Public Industrial Technology Project(G20160014)。
文摘The preparation of high-quality perovskite films with optimal morphologies is important for achieving highperformance perovskite photodetectors(PPDs). An effective strategy to optimize the morphologies is to add antisolvents during the spin-coating steps. In this work, a novel environment-friendly antisolvent tert-amyl alcohol(TAA) is employed first to improve the quality of perovskite films, which can effectively regulate the formation of an intermediate phase staged in between a liquid precursor phase and a solid perovskite phase due to its moderate polarity and further promote the homogeneous nucleation and crystal growth, thus leading to the formation of high-quality perovskite films and enhanced photodetector performance. As a result, the responsivity of the PPD reaches 1.56 A/W under the illumination of 532 nm laser with the power density of 6.37 μW=cm^(2) at a bias voltage of -2 V, which is good responsivity for PPDs with the vertical structure and only CH_(3)NH_(3)PbI_(3) perovskite as the photosensitive material. The corresponding detectivity reaches 1.47×10^(12) Jones, while the linear dynamic range reaches 110 dB. These results demonstrate that our developed green antisolvent TAA has remarkable advantages for the fabrication of high-performance PPDs and can provide a reference for similar research work.
基金National Natural Science Foundation of China(12005108,61701434,61735010)National Key Research and Development Program of China(2017YFA0700202)+2 种基金Natural Science Foundation of Shandong Province(ZR2020FK008,ZR2020QF016,ZR2021MF014)Special Funding of the Taishan Scholar Project(tsqn201909150)Qingchuang Science and Technology Plan of Shandong Universities(2019KJN001).
文摘Active control of the electromagnetically induced transparency(EIT)analog is desirable in photonics development.Here,we theoretically and experimentally proposed a novel terahertz(THz)asymmetric metasurface structure that can possess high-sensitivity modulation under extremely low power density by integrating perovskite or graphene.Using the novel metasurface structure with the perovskite coating,the maximum amplitude modulation depth(AMD)of this perovskite-based device reached 490.53%at a low power density of 12.8037 mW/cm^(2).In addition,after the novel THz metasurface structure was combined with graphene,this graphene-based device also achieved high AMD with the maximum AMD being 180.56%at 16.312 mW/cm^(2),and its transmission amplitude could be electrically driven at a low bias voltage.The physical origin of this modulation was explained using a two-oscillator EIT model.This work provides a promising platform for developing high-sensitivity THz sensors,light modulators,and switches.
