液态金属基微流体惯性开关,因其集感控于一体而得到重点关注。在开关设计中,改变流体与微通道壁面的接触角可以实现开关阈值范围的调节,提高微流体惯性开关的灵敏性。面向镓铟锡合金基微流体惯性开关,研究通过刻蚀-相分离法对微流道基底...液态金属基微流体惯性开关,因其集感控于一体而得到重点关注。在开关设计中,改变流体与微通道壁面的接触角可以实现开关阈值范围的调节,提高微流体惯性开关的灵敏性。面向镓铟锡合金基微流体惯性开关,研究通过刻蚀-相分离法对微流道基底(Polymethyl methacrylate,PMMA)进行表面超疏液改性,使PMMA表面同时发生化学刻蚀、相分离和SiO2沉淀过程,进而形成PMMA-SiO2的梯度粗糙表面。详细研究溶剂配置、成分配比和反应工艺参数对PMMA表面粗糙度的影响,并且开展超景深显微镜、扫描电子显微镜(Scanning electron microscope,SEM)、原子力显微镜(Atomic force microscope,AFM)和红外光谱仪的表征,发现使用四氢呋喃和无水乙醇按1∶1比例配比,且加入15 mg/mL的二氧化硅时,能够得到更有利于PMMA疏液性的表面粗糙结构。最终,通过此表面改性方法,成功实现镓铟锡合金基微流体加速度开关阈值从52.54g改进到了28.62g,满足了原液态开关的设计要求。展开更多
Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study th...Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.展开更多
Icing on the surface of aircraft will not only aggravate its quality and affect flight control,but even cause safety accidents,which is one of the important factors restricting all-weather flight.Bio-inspired anti-ici...Icing on the surface of aircraft will not only aggravate its quality and affect flight control,but even cause safety accidents,which is one of the important factors restricting all-weather flight.Bio-inspired anti-icing surfaces have gained great attention recently due to their low-hysteresis,non-stick properties,slow nucleation rate and low ice adhesion strength.These bio-inspired anti-icing surfaces,such as superhydrophobic surfaces,slippery liquid-infused porous surfaces and quasi-liquid film surfaces,have realized excellent anti-icing performance at various stages of icing.However,for harsh environment,there are still many problems and challenges.From the perspective of bioinspiration,the mechanism of icing nucleation,liquid bounce and ice adhesion has been reviewed together with the application progress and bottleneck issues about anti-icing in view of the process of icing.Subsequently,the reliability and development prospect of active,passive and active-passive integrated anti-icing technology are discussed,respectively.展开更多
Super hydrophobic copper wafer was prepared by means of solution immersion and surface self-assembly methods. Different immersion conditions were explored for the best hydrophobic surface. Scanning electron microscopy...Super hydrophobic copper wafer was prepared by means of solution immersion and surface self-assembly methods. Different immersion conditions were explored for the best hydrophobic surface. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and water contact angle measurements were used to investigate the morphologies, microstructures, chemical compositions and hydrophobicity of the produced films on copper substrates, respectively. Results show that the super hydrophobic surface is composed of micro structure of Cu 7 S 4 . The films present a high water contact angle larger than 150°, a low sliding angle less than 3°, good abrasion resistance and storage stability. The molecular dynamics simulation confirms that N-dodecyl mercaptan molecules link up with Cu 7 S 4 admirably, compared with Cu, which contributes to the stable super hydrophobic surface.展开更多
The capability to design and modulate materials, shapes, heat transfer, and mass mixing during the process of developing chemical reactors has allowed researchers to explore millions of chemical reactions and assays. ...The capability to design and modulate materials, shapes, heat transfer, and mass mixing during the process of developing chemical reactors has allowed researchers to explore millions of chemical reactions and assays. However, despite the advantages in engineering array-based microreactors or microfluidic systems, the wetting attachment between solutions of reagents/products and the glass or polymer substrates of containers leads to difficulties in collecting products effectively and preventing channel blockage. Herein we present a miniature droplet reactor which takes advantage of the anti-wetting and low-adhesive properties of nanoparticle-derived superhydrophobic pedestals, allowing aqueous droplets to be manipulated freely but also providing a confined environment for performing a series of aqueous phase chemical reactions on a small scale. Gas- or precipitate- forming reactions can also be performed inside this miniature reactor. Most importantly, reaction products in liquid, solid or gaseous states can be collected effectively, which allows the harvesting of valuable products formed in limited amounts. Such a miniature reactor built on superhydrophobic pedestals provides a new way of performing common chemical reactions and may open the door to the design of next-generation microreaction systems.展开更多
文摘液态金属基微流体惯性开关,因其集感控于一体而得到重点关注。在开关设计中,改变流体与微通道壁面的接触角可以实现开关阈值范围的调节,提高微流体惯性开关的灵敏性。面向镓铟锡合金基微流体惯性开关,研究通过刻蚀-相分离法对微流道基底(Polymethyl methacrylate,PMMA)进行表面超疏液改性,使PMMA表面同时发生化学刻蚀、相分离和SiO2沉淀过程,进而形成PMMA-SiO2的梯度粗糙表面。详细研究溶剂配置、成分配比和反应工艺参数对PMMA表面粗糙度的影响,并且开展超景深显微镜、扫描电子显微镜(Scanning electron microscope,SEM)、原子力显微镜(Atomic force microscope,AFM)和红外光谱仪的表征,发现使用四氢呋喃和无水乙醇按1∶1比例配比,且加入15 mg/mL的二氧化硅时,能够得到更有利于PMMA疏液性的表面粗糙结构。最终,通过此表面改性方法,成功实现镓铟锡合金基微流体加速度开关阈值从52.54g改进到了28.62g,满足了原液态开关的设计要求。
基金Project(50435030) supported by the National Natural Science foundation of ChinaProject supported by the Program for New Century Excellent Talents in Chinese University Project(GZ080010) supported by the Open Research Fund Program of Jiangsu Province Key Laboratory for Photon Manufacturing Science and Technology
文摘Twelve samples with periodic array square pillars microstructure were prepared on the silicon wafer by plasma etching techniques, on which space b of the square pillars increased from 5 to 60 μm. In order to study the effect ofb on the wettability of the rough surface, the effects of apparent contact angle （CA） and sliding angle （a） of the droplet on the rough surface were measured with the contact angle meter. The results show that the experimental values of CA well agree with the classical wetting theory and a decreases with the increase of b. Two drop shapes exist on the samples＇ surface, corresponding to the Cassie state and the Wenzel state respectively. The contact state in which a drop would settle depends typically on the size of b. On the role of gravitation, the irreversible transition of a drop from Cassie state to Wenzel state should occur at a certain space of the square pillars. Since the transition has implications on the application of super-hydrophobic rough surfaces, theoretically, the prediction of wetting state transition on square pillar array micro-structured surfaces provides an intuitionistic guidance for the design of steady superhydrophobic surfaces.
基金financially supported by the National Natural Science Foundation of China(Nos.T2121003,51725501,51935001,52205297).
文摘Icing on the surface of aircraft will not only aggravate its quality and affect flight control,but even cause safety accidents,which is one of the important factors restricting all-weather flight.Bio-inspired anti-icing surfaces have gained great attention recently due to their low-hysteresis,non-stick properties,slow nucleation rate and low ice adhesion strength.These bio-inspired anti-icing surfaces,such as superhydrophobic surfaces,slippery liquid-infused porous surfaces and quasi-liquid film surfaces,have realized excellent anti-icing performance at various stages of icing.However,for harsh environment,there are still many problems and challenges.From the perspective of bioinspiration,the mechanism of icing nucleation,liquid bounce and ice adhesion has been reviewed together with the application progress and bottleneck issues about anti-icing in view of the process of icing.Subsequently,the reliability and development prospect of active,passive and active-passive integrated anti-icing technology are discussed,respectively.
基金Supported by the Beijing Youth Fellowship Program and the Fundamental Research Funds for the Central Universities(2011YXL056)
文摘Super hydrophobic copper wafer was prepared by means of solution immersion and surface self-assembly methods. Different immersion conditions were explored for the best hydrophobic surface. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and water contact angle measurements were used to investigate the morphologies, microstructures, chemical compositions and hydrophobicity of the produced films on copper substrates, respectively. Results show that the super hydrophobic surface is composed of micro structure of Cu 7 S 4 . The films present a high water contact angle larger than 150°, a low sliding angle less than 3°, good abrasion resistance and storage stability. The molecular dynamics simulation confirms that N-dodecyl mercaptan molecules link up with Cu 7 S 4 admirably, compared with Cu, which contributes to the stable super hydrophobic surface.
基金The authors are grateful for a grant from the Major State Basic Research Development Program （No. 2007CB936403）, the National Natural Science Foundation of China （No. 20571077）, and the China Postdoctoral Science Foundation （No. 20100470557）.
文摘The capability to design and modulate materials, shapes, heat transfer, and mass mixing during the process of developing chemical reactors has allowed researchers to explore millions of chemical reactions and assays. However, despite the advantages in engineering array-based microreactors or microfluidic systems, the wetting attachment between solutions of reagents/products and the glass or polymer substrates of containers leads to difficulties in collecting products effectively and preventing channel blockage. Herein we present a miniature droplet reactor which takes advantage of the anti-wetting and low-adhesive properties of nanoparticle-derived superhydrophobic pedestals, allowing aqueous droplets to be manipulated freely but also providing a confined environment for performing a series of aqueous phase chemical reactions on a small scale. Gas- or precipitate- forming reactions can also be performed inside this miniature reactor. Most importantly, reaction products in liquid, solid or gaseous states can be collected effectively, which allows the harvesting of valuable products formed in limited amounts. Such a miniature reactor built on superhydrophobic pedestals provides a new way of performing common chemical reactions and may open the door to the design of next-generation microreaction systems.
