AFM Probe Variable Stiffness via Movable End Frame
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Solution Overview
Problem
Conventional atomic force microscope (AFM) probes face challenges in simultaneously performing surface topography and nano-indentation tests due to fixed stiffness, which leads to errors in measuring mechanical properties like modulus of elasticity and hardness, as they cannot accommodate the differing stiffness requirements for these tests.
Innovation Solution
An AFM probe with an elastically deformable frame and a stopper mechanism that controls the movement of the AFM tip within predetermined ranges, allowing for variable stiffness to suit both surface topography and nano-indentation tests, featuring a diamond-shaped frame with stopper members that adjust stiffness based on the test type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the AFM cantilever has fixed stiffness, then the structure is simple and easy to manufacture, but it cannot meet both surface topography testing requiring low stiffness and indentation testing requiring high stiffness
Solution Approach 1:
The patent applies the dynamics principle by making the frame structure capable of changing its stiffness characteristic dynamically. The frame includes a movable end that can shift position along the longitudinal axis, transforming the fixed-stiffness system into a variable-stiffness system. This allows the AFM probe to adapt between low stiffness for surface topography testing and high stiffness for indentation testing by simply repositioning the movable end, without requiring multiple different probes.
Solution Approach 2:
The patent applies segmentation by dividing the frame into distinct segments: a fixed end, a movable end, and intermediate portions. The movable end can be positioned at different locations along the longitudinal axis, effectively segmenting the frame's stiffness characteristics. This segmentation allows independent control of the stiffness parameter while maintaining a single integrated probe structure.
2Measurement precision
If the AFM cantilever has fixed stiffness, then the device complexity is low, but the measurement precision for mechanical properties deteriorates due to horizontal displacement errors
Solution Approach 1:
The patent applies asymmetry by designing the frame with a specific geometric configuration where the cross-sectional shape and dimensions vary along the longitudinal axis. The frame includes portions with different thicknesses and geometries that create asymmetric stiffness distribution. This asymmetric design, combined with the movable end positioning, allows the frame to resist horizontal displacement forces more effectively while maintaining vertical compliance, thereby improving measurement precision for indentation tests.
Solution Approach 2:
The movable end that can reposition along the longitudinal axis dynamically adjusts the frame's stiffness characteristics. When positioned closer to the fixed end, the frame exhibits higher stiffness for indentation testing, reducing horizontal displacement errors. This dynamic adjustment capability directly improves measurement precision by optimizing the frame's mechanical response to different testing requirements.
3Adaptability or versatility
If the AFM cantilever has fixed stiffness, then the manufacturing is simple, but the versatility for different testing scenarios is limited
Solution Approach 1:
The patent applies universality by designing a single AFM probe structure that can perform multiple testing functions: surface topography testing, indentation testing, and mechanical property measurement. The movable end mechanism allows the same probe to adapt its stiffness characteristics for different testing scenarios, eliminating the need for multiple specialized probes and simplifying the overall testing system while maintaining manufacturing feasibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate measurement of mechanical properties by controlling the AFM tip's movement and stiffness, reducing errors and allowing for both low and high stiffness conditions as needed for different testing scenarios.
Implementation Method 1
an elastically deformable frame having a fixed end and a movable end on one axis, wherein the movable end is configured to move along the axis relative to the fixed end
Implementation Method 2
a stopper configured to limit or dampen the movement of the movable end toward the fixed end depending upon a relative position of the movable end to the fixed end
Data Source
AI summary
Disclosed is an atomic force microscope (AFM) probe for use in an AFM, and more particularly, an AFM probe suitable for testing the topography and mechanical properties of a microstructure having a size on the order of micrometers or nanometers. To this end, an AFM probe according to the present invention comprises an elastically deformable frame having a fixed end and a movable end on one axis; an AFM tip supported by the movable end to be movable against a test sample in a direction of the axis; and a stopper provided on an inner surface of the frame to control a movement of the AFM tip within a predetermined range.