Continuous Curvilinear Scanning Probe Microscopy for Ambient Force Measurement
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Solution Overview
Problem
Conventional atomic force microscopy (AFM) systems face challenges in measuring interaction forces under ambient conditions due to capillary condensation, which introduces additional adhesion forces and complicates the measurement of magnetic, van der Waals, or electrostatic forces, and cyclic scanning methods do not allow for constant linear speed, leading to non-stationary measurements.
Innovation Solution
Implementing a continuous curvilinear relative displacement of the probe with respect to the sample using harmonic voltages applied to piezoelectric actuators, allowing for uniform movement without stopping or sudden speed changes, thereby avoiding capillary condensation and enabling constant-speed measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cyclic scanning mode is used in conventional AFM, then the measurement can be performed under ambient conditions, but capillary condensation occurs introducing additional adhesion forces and the measurement speed cannot be constant
Solution Approach 1:
The patent applies curvilinear continuous motion (circular or elliptical trajectories) of the probe relative to the sample surface, replacing the conventional cyclic back-and-forth linear scanning. This curvilinear motion eliminates stopping and reversing, preventing capillary condensation formation while maintaining ambient operation, thus resolving the contradiction between ease of operation and measurement precision
Solution Approach 2:
The patent implements continuous unidirectional curvilinear scanning motion that never stops or reverses, ensuring the probe continuously moves along a closed curve. This continuous action prevents the stationary periods that cause capillary condensation, enabling precise force measurements under ambient conditions without the harmful effects of cyclic scanning
2Area of stationary object
If cyclic scanning is performed with stopping at turning points, then the scan can cover the entire surface, but the measurement speed varies and stationary state cannot be observed
Solution Approach 1:
By using circular or elliptical curvilinear trajectories, the probe continuously covers the surface area while maintaining constant speed throughout the entire measurement cycle. The curved path eliminates the need for stopping and reversing at turning points, thus achieving both complete surface coverage and constant measurement speed simultaneously
3Ease of operation
If the probe stops or changes direction during scanning, then cyclic scanning can be performed, but capillary condensation forms adding adhesion forces of several tens of nN
Solution Approach 1:
The continuous curvilinear motion ensures the probe never stops or reverses direction, maintaining constant movement along a closed curve. This eliminates the stationary periods necessary for capillary condensation to form, thereby removing the harmful adhesion forces while preserving the ability to perform complete surface scans under ambient conditions
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
This approach allows for precise, constant-speed measurements of interaction forces, including adhesion and friction forces, without the interference of capillary forces, and enables higher displacement speeds, facilitating surface modifications and improved measurement accuracy.
Implementation Method 1
harmonic voltages applied to piezoelectric actuators, allowing for uniform movement without stopping or sudden speed changes
Implementation Method 2
This deflection is generally detected by an optical system consisting of a laser beam which is reflected on the end of the cantilever and whose path is guided using mirrors, and then picked up by a photodetector
Implementation Method 3
a nano meniscus of capillary condensation due to the humidity of the air and the hydrophilicity of the surfaces can form between the tip and the surface, typically for contact times close to and beyond a millisecond. Laplace's depression in this capillary condensation meniscus generates an adhesion force
Implementation Method 4
the non-contact mode: the cantilever oscillates near the surface of the sample around its resonance frequency at a low amplitude of the order of a few nm
Implementation Method 5
It is the attractive forces which dominate (forces of Van der Waals, magnetic, electrostatic...)
Data Source
Figure 1~2b
Figure 2c~3c
Figure 4a~4c
AI summary
The invention relates to processes for the modification of surfaces and on processes for the measurement of adhesion forces and of different forces of interaction (friction forces, adhesion forces) by scanning probe microscopy functioning in continuous <<curvilinear>> mode, as well as to a scanning probe microscope and a device permitting the implementation of said processes.