Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable prope...Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate.Among many fabrication methods for stimulus-responsive structures,femtosecond laser direct writing(FsLDW)has received increasing attention because of its high precision,simplicity,true three-dimensional machining ability,and wide applicability to almost all materials.This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW.Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies,different stimulating factors that can trigger structural responses of prepared intelligent structures,such as magnetic field,light,temperature,pH,and humidity,are emphatically summarized.Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW,as well as the present obstacles and forthcoming development opportunities,are discussed.展开更多
Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus str...Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus structure is a promising approach to achieve shape transformation based on its heterogeneous chemical or physical properties on opposite sides.However, the heterogeneity is generally realized by multi-step processing, different materials,and/or different processing parameters. Here, we present a simple and flexible method of producing p H-sensitive Janus microactuators from a single material, using the same laser printing parameters. These microactuators exhibit reversible structural deformations with large bending angles of ~31°and fast response(~0.2 s) by changing the p H value of the aqueous environment. Benefited from the high flexibility of the laser printing technique and the spatial arrangements, pillar heights, and bending directions of microactuators are readily controlled,enabling a variety of switchable ordered patterns and complex petal-like structures on flat surfaces and inside microchannels. Finally, we explore the potential applications of this method in information encryption/decryption and microtarget capturing.展开更多
Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ treatment. These versatile small biomedical robots are expected to ...Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ treatment. These versatile small biomedical robots are expected to realize direct access to the tumor or disease site for precise treatment, which requires real-time and high-resolution in vivo tracking as feedback for the microrobots’ actuation and control. Among current biomedical imaging methods, photoacoustic imaging(PAI) is presenting its outstanding performances in the tracking of microrobots in the human body derived from its great advantages of excellent imaging resolution and contrast in deep tissue. In this review, we summarize the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective,we also provide some insight into the future of PAI technology in clinical applications.展开更多
Optical-resolution photoacoustic microscopy(OR-PAM)has been developed for anatomical,functional,and molecular imaging but usually requires multiple scanning for different contrasts.We present five-wavelength OR-PAM fo...Optical-resolution photoacoustic microscopy(OR-PAM)has been developed for anatomical,functional,and molecular imaging but usually requires multiple scanning for different contrasts.We present five-wavelength OR-PAM for simultaneous imaging of hemoglobin concentration,oxygen saturation,blood flow speed,and lymphatic vessels in single raster scanning.We develop a five-wavelength pulsed laser via stimulated Raman scattering.The five pulsed wavelengths,i.e.,532,545,558,570,and 620∕640 nm,are temporally separated by several hundreds of nanoseconds via different optical delays in fiber.Five photoacoustic images at these wavelengths are simultaneously acquired in a single scanning.The 532-and 620∕640-nm wavelengths are used to image the blood vessels and dye-labeled lymphatic vessels.The blood flow speed is measured by a dual-pulse method.The oxygen saturation is calculated and compensated for by the Grüneisen-relaxation effect.In vivo imaging of hemoglobin concentration,oxygen saturation,blood flow speed,and lymphatic vessels is demonstrated in preclinical applications of cancer detection,lymphatic clearance monitoring,and functional brain imaging.展开更多
In this work,(-201)β-Ga2O3 films are grown on GaN substrate by metal organic chemical vapor deposition(MOCVD).It is revealed that theβ-Ga2O3 film grown on GaN possesses superior crystal quality,material homogeneity ...In this work,(-201)β-Ga2O3 films are grown on GaN substrate by metal organic chemical vapor deposition(MOCVD).It is revealed that theβ-Ga2O3 film grown on GaN possesses superior crystal quality,material homogeneity and surface morphology than the results of common heteroepitaxialβ-Ga2O3 film based on sapphire substrate.Further,the relevance between the crystal quality of epitaxialβ-Ga2O3 film and theβ-Ga2O3/GaN interface behavior is investigated.Transmission electron microscopy result indicates that the interface atom refactoring phenomenon is beneficial to relieve the mismatch strain and improve the crystal quality of subsequentβ-Ga2O3 film.Moreover,the energy band structure ofβ-Ga2O3/GaN heterostructure grown by MOCVD is investigated by X-ray photoelectron spectroscopy and a large conduction band offset of 0.89 eV is obtained.The results in this work not only convincingly demonstrate the advantages ofβ-Ga2O3 films grown on GaN substrate,but also show the great application potential of MOCVDβ-Ga2O3/GaN heterostructures in microelectronic applications.展开更多
Distinguishing early-stage tumors from normal tissues is of great importance in cancer diagnosis.We report fiberbased confocal visible/near-infrared(NIR)optical-resolution photoacoustic microscopy that can image tumor...Distinguishing early-stage tumors from normal tissues is of great importance in cancer diagnosis.We report fiberbased confocal visible/near-infrared(NIR)optical-resolution photoacoustic microscopy that can image tumor microvasculature,oxygen saturation,and nanoprobes in a single scanning.We develop a cost-efficient single laser source that provides 532,558,and 1064 nm pulsed light with sub-microseconds wavelength switching time.Via dual-fiber illumination,we can focus the three beams to the same point.The optical and acoustic foci are confocally aligned to optimize the sensitivity.The visible and NIR wavelengths enable simultaneous tumor imaging with three different contrast modes.Results show obvious angiogenesis,significantly elevated oxygen saturation,and accumulated nanoparticles in the tumor regions,which offer comprehensive information to detect the tumor.This approach also allows us to identify feeding and draining vessels of the tumor and thus to determine local oxygen extraction fraction.In the tumor region,the oxygen extraction fraction significantly decreases along with tumor growth,which can also assist in tumor detection and staging.Fiber-based confocal visible/NIR photoacoustic microscopy offers a new tool for early detection of cancer.展开更多
Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When ...Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When combined,the two components can undergo visible light-induced singleelectron transfer,and serve as a versatile and effective alkyl radical generator.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 52122511, 52105492, and 62005262)the National Key Research and Development Program of China (No. 2021YFF0502700)+2 种基金the Students’ Innovation and Entrepreneurship Foundation of USTC (Nos. CY2022G32 and XY2022G02CY)the USTC Research Funds of the Double First-Class Initiative (No. YD2340002009)CAS Project for Young Scientists in Basic Research (No. YSBR-049)
文摘Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate.Among many fabrication methods for stimulus-responsive structures,femtosecond laser direct writing(FsLDW)has received increasing attention because of its high precision,simplicity,true three-dimensional machining ability,and wide applicability to almost all materials.This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW.Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies,different stimulating factors that can trigger structural responses of prepared intelligent structures,such as magnetic field,light,temperature,pH,and humidity,are emphatically summarized.Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW,as well as the present obstacles and forthcoming development opportunities,are discussed.
基金the Hong Kong Scholar Program (XJ2018035) for their financial supportsupported by Research Grants Council of Hong Kong (No. JLFS/E-402/18)National Natural Science Foundation of China (No. 51805509)。
文摘Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus structure is a promising approach to achieve shape transformation based on its heterogeneous chemical or physical properties on opposite sides.However, the heterogeneity is generally realized by multi-step processing, different materials,and/or different processing parameters. Here, we present a simple and flexible method of producing p H-sensitive Janus microactuators from a single material, using the same laser printing parameters. These microactuators exhibit reversible structural deformations with large bending angles of ~31°and fast response(~0.2 s) by changing the p H value of the aqueous environment. Benefited from the high flexibility of the laser printing technique and the spatial arrangements, pillar heights, and bending directions of microactuators are readily controlled,enabling a variety of switchable ordered patterns and complex petal-like structures on flat surfaces and inside microchannels. Finally, we explore the potential applications of this method in information encryption/decryption and microtarget capturing.
基金This work was partially supported by the Research Grants Council of the Hong Kong Special Administrative Region(Nos.11103320,11215817,and 11101618)。
文摘Microrobots-assisted drug delivery and surgery have been always in the spotlight and are highly anticipated to solve the challenges of cancer in situ treatment. These versatile small biomedical robots are expected to realize direct access to the tumor or disease site for precise treatment, which requires real-time and high-resolution in vivo tracking as feedback for the microrobots’ actuation and control. Among current biomedical imaging methods, photoacoustic imaging(PAI) is presenting its outstanding performances in the tracking of microrobots in the human body derived from its great advantages of excellent imaging resolution and contrast in deep tissue. In this review, we summarize the PAI techniques, imaging systems, and their biomedical applications in microrobots tracking in vitro and in vivo. From a robotic tracking perspective,we also provide some insight into the future of PAI technology in clinical applications.
基金This work was partially supported by the National Natural Science Foundation of China(NSFC)(Nos.81627805 , 61805102)Research Grants Council of the Hong Kong Special Administrative Region(Nos.21205016,11215817, 11101618)Shenzhen Basic Research Project(No.JCYJ20170413140519030).
文摘Optical-resolution photoacoustic microscopy(OR-PAM)has been developed for anatomical,functional,and molecular imaging but usually requires multiple scanning for different contrasts.We present five-wavelength OR-PAM for simultaneous imaging of hemoglobin concentration,oxygen saturation,blood flow speed,and lymphatic vessels in single raster scanning.We develop a five-wavelength pulsed laser via stimulated Raman scattering.The five pulsed wavelengths,i.e.,532,545,558,570,and 620∕640 nm,are temporally separated by several hundreds of nanoseconds via different optical delays in fiber.Five photoacoustic images at these wavelengths are simultaneously acquired in a single scanning.The 532-and 620∕640-nm wavelengths are used to image the blood vessels and dye-labeled lymphatic vessels.The blood flow speed is measured by a dual-pulse method.The oxygen saturation is calculated and compensated for by the Grüneisen-relaxation effect.In vivo imaging of hemoglobin concentration,oxygen saturation,blood flow speed,and lymphatic vessels is demonstrated in preclinical applications of cancer detection,lymphatic clearance monitoring,and functional brain imaging.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.JB181108)the National Natural Science Foundation of China(Grant No.61904139)the Science and Technology Program of Guangzhou(Grant No.201904010457)。
文摘In this work,(-201)β-Ga2O3 films are grown on GaN substrate by metal organic chemical vapor deposition(MOCVD).It is revealed that theβ-Ga2O3 film grown on GaN possesses superior crystal quality,material homogeneity and surface morphology than the results of common heteroepitaxialβ-Ga2O3 film based on sapphire substrate.Further,the relevance between the crystal quality of epitaxialβ-Ga2O3 film and theβ-Ga2O3/GaN interface behavior is investigated.Transmission electron microscopy result indicates that the interface atom refactoring phenomenon is beneficial to relieve the mismatch strain and improve the crystal quality of subsequentβ-Ga2O3 film.Moreover,the energy band structure ofβ-Ga2O3/GaN heterostructure grown by MOCVD is investigated by X-ray photoelectron spectroscopy and a large conduction band offset of 0.89 eV is obtained.The results in this work not only convincingly demonstrate the advantages ofβ-Ga2O3 films grown on GaN substrate,but also show the great application potential of MOCVDβ-Ga2O3/GaN heterostructures in microelectronic applications.
基金supported by the National Natural Science Foundation of China(62003151,61925404,62074122,and 61904139)the Key Research and Development Program in Shaanxi Province(2016KTZDGY-03-01)。
基金National Natural Science Foundation of China(61805102,81627805)Research Grants Council of the Hong Kong Special Administrative Region(11101618,11215817,21205016)Shenzhen Basic Research Project(JCYJ20170413140519030)。
文摘Distinguishing early-stage tumors from normal tissues is of great importance in cancer diagnosis.We report fiberbased confocal visible/near-infrared(NIR)optical-resolution photoacoustic microscopy that can image tumor microvasculature,oxygen saturation,and nanoprobes in a single scanning.We develop a cost-efficient single laser source that provides 532,558,and 1064 nm pulsed light with sub-microseconds wavelength switching time.Via dual-fiber illumination,we can focus the three beams to the same point.The optical and acoustic foci are confocally aligned to optimize the sensitivity.The visible and NIR wavelengths enable simultaneous tumor imaging with three different contrast modes.Results show obvious angiogenesis,significantly elevated oxygen saturation,and accumulated nanoparticles in the tumor regions,which offer comprehensive information to detect the tumor.This approach also allows us to identify feeding and draining vessels of the tumor and thus to determine local oxygen extraction fraction.In the tumor region,the oxygen extraction fraction significantly decreases along with tumor growth,which can also assist in tumor detection and staging.Fiber-based confocal visible/NIR photoacoustic microscopy offers a new tool for early detection of cancer.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB17000000)the National Natural Science Foundation of China (Nos.21672227, 21922113)+3 种基金the National Key Research and Development Program of China (No.2017YFA0206903)Beijing Natural Science Foundation (No.L182020)Fundamental Research Funds for the Central Universities (No.FRF-TP-19-013B1)K.C.Wong Education Foundation,and the TIPC Director’s Fund。
文摘Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed,featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor.When combined,the two components can undergo visible light-induced singleelectron transfer,and serve as a versatile and effective alkyl radical generator.