•A very compact vector force sensor achieved through on-chip monolithic integration strategy.•Introduction of microstructures on the surface of PDMS elastomers enhances the sensor’s performance in ...terms of sensitivity and hysteresis.•Simultaneous fabrication of micro-LEDs and PD on sapphire-based AlGaInP MQW chips.•Compatible with wafer-level microfabrication technology, enabling high-cost effectiveness.
Optical principle-based force sensors offer significant advantages in detection applications for surgical robots and wearable devices. With the rapid development in these fields, there is an increasingly urgent demand for improving sensor performance and reducing sensor size. Here, we present a monolithic micro-vector force sensor by integrating the sapphire based AlGaInP micro light-emitting diodes (micro-LEDs) and a surface micro-structured polydimethylsiloxane (PDMS) elastomer. The sensor primarily operates based on the overlapping between the emission spectra and the detection spectra of the multiple quantum well (MQW) structure in the micro-LEDs and the modulation of the reflectance of the sapphire interface by highly elastic microstructures. This monolithic micro-vector force sensor is characterized by its small footprint with a diameter of only ∼7 mm, and it exhibits good real-time response performance with response sensitivities to normal force and shear force of 0.38 nA/mN (0–2 N) and 1.3 nA/mN (0–200 mN). Furthermore, this monolithic integrated device can be manufactured on a large scale and at low cost using wafer-level microfabrication processes. Additionally, the sensor operates in the biologically safe red light spectrum, thus offering broad prospects for applications in fields such as biomedicine and wearable devices.
This paper presents a novel electrochemical processing technique, mask electrolyte jet machining (MEJM), for the fabrication of surface microstructures. MEJM combines jet electrochemical ...micromachining (Jet-ECM) and through-mask electrochemical micromachining (TMEMM), combining the advantages of TMEMM, which is a high-throughput process, and of Jet-ECM, with its adjustable flow field. The effects of a mobile nozzle on electrolyte flow are investigated, and a new modeling approach for large translational movements is proposed. An analysis of the accuracy and reliability of the proposed method is presented. Microprotrusions and microdimples are produced to high precision and with excellent consistency of dimensional variation (maximum standard deviation 2.171 μm). The results suggest the possibility of an affordable technique for batch fabrication of surface microstructures with high efficiency and precision.
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•A novel electrochemical process for fabrication of micro surface structures.•Assimilate the strong point of TMEMM and Jet-ECM, present a high-throughput process with adjustable flow field.•The process shows potential especially considering large area complex geometries.
The rose petal effect and the modes of superhydrophobicity Bhushan, Bharat; Nosonovsky, Michael
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
10/2010, Letnik:
368, Številka:
1929
Journal Article
Recenzirano
The wetting of rough surfaces remains a subject of active investigation by scientists. The contact angle (CA) is a traditional parameter used to characterize the hydrophobicity/philicity of a solid ...surface. However, it was found recently that high CAs can coexist with strong adhesion between water and a solid surface in the case of the so-called 'rose petal effect'. Several additional parameters have been proposed to characterize the interaction of water with a rough solid surface, including the CA hysteresis, the ability of water droplets to bounce off a solid surface, the tilt angle needed to initiate the flow of a droplet, and the normal and shear adhesion. It is clear now that wetting is not characterized by a single parameter, since several modes or regimes of wetting of a rough surface can exist, including the Wenzel, Cassie, lotus and petal. Understanding the wetting of rough surfaces is important in order to design non-adhesive surfaces for various applications.
Bitumen, also called asphalt binder, plays important roles in many industrial applications. It is used as the primary binding agent in asphalt concrete, as a key component in damping systems such as ...rubber, and as an indispensable additive in paint and ink. Consisting of a large number of hydrocarbons of different sizes and polarities, together with heteroatoms and traces of metals, bitumen displays rich surface microstructures that affect its rheological properties. This paper reviews the current understanding of bitumen's surface microstructures characterized by Atomic Force Microscopy (AFM). Microstructures of bitumen develop to different forms depending on crude oil source, thermal history, and sample preparation method. While some bitumens display surface microstructures with fine domains, flake-like domains, and dendrite structuring, ‘bee-structures’ with wavy patterns several micrometers in diameter and tens of nanometers in height are commonly seen in other binders. Controversy exists regarding the chemical origin of the ‘bee-structures’, which has been related to the asphaltene fraction, the metal content, or the crystallizing waxes in bitumen. The rich chemistry of bitumen can result in complicated intermolecular associations such as coprecipitation of wax and metalloporphyrins in asphaltenes. Therefore, it is the molecular interactions among the different chemical components in bitumen, rather than a single chemical fraction, that are responsible for the evolution of bitumen's diverse microstructures, including the ‘bee-structures’. Mechanisms such as curvature elasticity and surface wrinkling that explain the rippled structures observed in polymer crystals might be responsible for the formation of ‘bee-structures’ in bitumen. Despite the progress made on morphological characterization of bitumen using AFM, the fundamental question whether the microstructures observed on bitumen surfaces represent its bulk structure remains to be addressed. In addition, critical technical challenges associated with AFM characterization of bitumen surface structures are discussed, with possible solutions recommended. For future work, combining AFM with other chemical analysis tools that can generate comparable high resolution to AFM would provide an avenue to linking bitumen's chemistry to its microscopic morphological and mechanical properties and consequently benefit the efforts of developing structure-related models for bituminous materials across the different length scales.
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•A general picture of the diverse surface microstructures of bitumen is provided.•Explanations about the chemical origin of ‘bee-structures’ are summarized.•Technical challenges on AFM characterization of bitumen morphology are identified.•Future work for chemical and microscopic mechanical characterization is discussed.
Rainfall plays a crucial role in the removal of particulate matter (PM) from plant leaves, influencing PM retention and the environmental behaviour of harmful substances that accumulate in PM. This ...study examined the PM retention capacity, particle size distributions, and wash-off rates of leaf surface PM from three common green tree species in northern China during two natural rainfall events (light rain: 8.3 mm; heavy rain: 54.2 mm), to investigate the relationship between the leaf traits, PM retention capacity, and PM wash-off process. Our results found that leaf morphometric characteristics, such as leaf size, length, width, and aspect ratio (length-to-width), had a negative and significant correlations with the PM retention capacity, but had no significant correlation with the leaf surface PM wash-off rate. Smaller leaves with low aspect ratios exhibited greater stability under external disturbances than large leaves with high aspect ratios, resulting in a higher PM retention capacity and lower wash-off rate. Ridges and grooves enhanced the PM retention capacity by increasing the leaf roughness. Rainfall could wash off all particle size ranges of leaf surface PM without altering their mechanical composition. Larger particles were more easily washed off. Euonymus japonicus, with its small leaf size and low aspect ratio, exhibited the highest PM retention capacity. Its curled leaf shape also hindered light rain from washing off leaf surface PM. Forsythia suspensa, with denser grooves and ridges compared with Prunus serrulata, exhibited a rougher leaf surface and higher PM retention capacity. However, this roughness may reduce wettability, making it easier for runoff to form on the leaf surface and dislodge leaf surface PM, resulting in F. suspensa having the highest wash-off rate. Our results highlight the synergy of different leaf traits on PM retention capacity and the PM stability after rainfall.
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•Accumulation of PM on three species' leaves was investigated in two rainfall events.•Synergy of leaf morphometric traits and microstructures determined PM retention.•Leaf morphometry had a greater impaction on PM retention than microstructures.•Curled leaf shape and rough surface hindered rain wash-off effect on leaf surface PM.
Marine biological fouling has a serious impact on artificial facilities, and traditional antifouling coatings are not beneficial to green development, which lead to the urgent to develop green ...strategies that can effectively prevent fouling. In this study, an innovative confluence of physical and biological approaches was employed to mitigate the harm caused by biofouling on a material substrate. Firstly, a hierarchical microstructured morphology was prepared on an aluminum surface by reactive ion etching and characterised. The antibacterial peptide, A-2S, was surface modified with dopamine as a coupling agent to produce a physico-biological synergistic antifouling surface. X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, and electrochemical experiments were then used to analyse the binding effect and corrosion resistance performance. A-2S was successfully modified on the sample surface and exhibited good corrosion resistance with a corrosion inhibition efficiency of 86.57 %. Compared to a bare aluminum plate, the microstructure surface has a certain inhibitory effect on fouling organisms, and the antifouling performance decreases over time. In contrast, the antimicrobial peptide synergistic surfaces demonstrated superior durable antifouling performance. Compared with the 50 % of the antifouling performance on the microstructure surface, the synergistic surface has a unique contact point effect of the microstructure and excellent antibacterial and bactericidal properties of antimicrobial peptides, resulting in a surface antifouling performance of over 80 %. The synergistic modification method enhanced the corrosion resistance of the material and reduced the adhesion of fouling organisms, mitigating the harm caused by biofouling on the marine equipment substrate.
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•Reactive ion etching was used to mimic the hierarchical microstructures of the epidermis of the springtail.•The physical-biological synergistic surface with highly efficient and durable antifouling effects was prepared.•Surface physicochemical properties and antifouling performance of sample surfaces were investigated.•MICR Al-DA-A surface exhibited excellent marine antifouling and anticorrosion performance.
A cathode for high‐rate performance lithium‐ion batteries (LIBs) has been developed from a crystal habit‐tuned nanoplate Li(Li0.17Ni0.25Mn0.58)O2 material, in which the proportion of (010) nanoplates ...(see figure) has been significantly increased. The results demonstrate that the fraction of the surface that is electrochemically active for Li+ transportation is a key criterion for evaluating the different nanostructures of potential LIB materials.
Silicon surface microstructures can significantly improve their reflection and absorption characteristics and are widely used in photovoltaics and optoelectronic detection. But there is little ...research on the infrared emission characteristics of microstructure silicon since silicon is an indirect bandgap material. Here, we fabricate surface microstructures on highly doped silicon by femtosecond laser scanning, enhancing its broadband infrared radiation significantly under electric driving. At 12 μm, it can be enhanced to 274% of the untreated silicon. Our results show that silicon with surface microstructures can be used as a wideband infrared emitter. This study provides a new method for realizing a broad-spectrum silicon-based electrical drive infrared light source.
•The Infrared radiation characteristics of highly doped silicon under electric driving was studied for the first time.•The infrared radiation of microstructure silicon was enhanced to 274% of the untreated silicon at 12 μm.•Broadband infrared radiation of highly doped silicon is enhanced significantly under electric driving.
Polycrystalline diamond (PCD) tools have gained popularity in machining industry ascribed to superior surface quality and durability at elevated temperature and abrasive forces. A major obstacle for ...high-speed PCD machining is the excessive heat production that transcend the heat dissipation capacity, resulting in reduced tool life and performance. Surface microstructures on PCD tools can improve thermal performance by increasing the heat transfer area and reducing the thermal contact resistance, therefore enhancement in durability and operation. Femtosecond laser processing is a non-contact, high precision and low thermal effect technique for creating superior quality microstructures. This study investigates the effects of cryogenic-assisted femtosecond laser processing in improvement of diamond microstructures quality. Initially the effects of different laser settings on the performance of the process were investigated by conducting single-factor experiments at ambient conditions. Later, the effects of cryogenic assistance on diamond irradiation, surface quality and chemical changes were investigated utilizing laser confocal scanning microscopy (LCSM), scanning electron microscopy (SEM) and Raman spectroscopy. Cryogenic laser ablation had no effect on the diamond removal rate, on contrary improved the surface quality by reducing the surface roughness and graphite disorderliness. This study reports superior surface quality finish for cryogenic assisted laser ablation than ambient conditions therefore it is recommended to irradiate PCD at low temperatures.
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•The law of influence of laser parameters on the processing results of PCD.•PCD processing using femtosecond laser at low temperature.•The processing effect of PCD at low temperature is better than that at room temperature.
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