In an operation mode of atomic force micro- scopy that uses a higher eigenmode to determine the physical properties of material surface, the ratio between the eigenfrequency of a higher flexural eigenmode and that of ...In an operation mode of atomic force micro- scopy that uses a higher eigenmode to determine the physical properties of material surface, the ratio between the eigenfrequency of a higher flexural eigenmode and that of the first flexural eigenmode was identified as an important parameter that affects the sensitivity and accessibility. Structure features such as cut-out are often used to tune the ratio of eigenfrequencies and to enhance the performance. However, there lacks a systematic and automatic method for tailoring the ratio. In order to deal with this issue, a shape and topology optimization problem is formulated, where the ratio between two eigenfrequen- cies is defined as a constraint and the area of the cantilever is maximized. The optimization problem is solved via the level set based method.展开更多
Accurately measuring the coefficient of friction(COF)is the fundamental prerequisite of superlubricity research.This study aimed to reduce the COF measurement resolutionΔμof atomic force microscopy(AFM).Based on the...Accurately measuring the coefficient of friction(COF)is the fundamental prerequisite of superlubricity research.This study aimed to reduce the COF measurement resolutionΔμof atomic force microscopy(AFM).Based on the theoretical model,a distinctive strategy was adopted to reduceΔμby optimizing the cantilever’s cross-section of the AFM probe,inspired by civil engineering.Δμcan be reduced by decreasing the width of the horizontal side wR and the wall thickness t and increasing the width of the vertical side wH.Moreover,the I-shape demonstrates the highest reduction inΔμ,followed by the U-shape.Considering the processability,the AFM probe with the U-shaped cross-sectional cantilever was investigated further,and the dimensions are 35μm wR,3.5μm wH,0.5μm t,50μm l(cantilever length),and 23μm htip(tip height).The finite element analysis results confirm its reliability.After being fabricated and calibrated,the AFM probe achieves the minimalΔμof 1.9×10^(–6)under the maximum normal force so far.Additionally,the friction detection capability of the fabricated AFM probe improves by 78 times compared to the commercial tipless-force modulation mode(TL-FM)AFM probe with the conventional solid rectangular cross-sectional cantilever.This study provides a powerful tool for measuring 10^(–6)COF.展开更多
文摘In an operation mode of atomic force micro- scopy that uses a higher eigenmode to determine the physical properties of material surface, the ratio between the eigenfrequency of a higher flexural eigenmode and that of the first flexural eigenmode was identified as an important parameter that affects the sensitivity and accessibility. Structure features such as cut-out are often used to tune the ratio of eigenfrequencies and to enhance the performance. However, there lacks a systematic and automatic method for tailoring the ratio. In order to deal with this issue, a shape and topology optimization problem is formulated, where the ratio between two eigenfrequen- cies is defined as a constraint and the area of the cantilever is maximized. The optimization problem is solved via the level set based method.
基金the financial support by the National Key R&D Program of China(2020YFA0711001)the National Natural Science Foundation of China(51975488,51991373,and 52235004).
文摘Accurately measuring the coefficient of friction(COF)is the fundamental prerequisite of superlubricity research.This study aimed to reduce the COF measurement resolutionΔμof atomic force microscopy(AFM).Based on the theoretical model,a distinctive strategy was adopted to reduceΔμby optimizing the cantilever’s cross-section of the AFM probe,inspired by civil engineering.Δμcan be reduced by decreasing the width of the horizontal side wR and the wall thickness t and increasing the width of the vertical side wH.Moreover,the I-shape demonstrates the highest reduction inΔμ,followed by the U-shape.Considering the processability,the AFM probe with the U-shaped cross-sectional cantilever was investigated further,and the dimensions are 35μm wR,3.5μm wH,0.5μm t,50μm l(cantilever length),and 23μm htip(tip height).The finite element analysis results confirm its reliability.After being fabricated and calibrated,the AFM probe achieves the minimalΔμof 1.9×10^(–6)under the maximum normal force so far.Additionally,the friction detection capability of the fabricated AFM probe improves by 78 times compared to the commercial tipless-force modulation mode(TL-FM)AFM probe with the conventional solid rectangular cross-sectional cantilever.This study provides a powerful tool for measuring 10^(–6)COF.
