Scanning Probe Microscope Actuator Segmentation for Rough Samples
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Solution Overview
Problem
Scanning probe microscopes face challenges in maintaining a constant tip-sample force when dealing with biological tissue samples that have large surface roughness, exceeding the range of nanoscanners, leading to loss of contact or increased force, which affects the accuracy of measurements.
Innovation Solution
Monitoring the movement of the piezo element and using external motors or actuators to adjust the cantilever's position when the piezo element reaches its limits, ensuring the probe maintains optimal contact and angle with the sample surface, even with large surface corrugations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the nanoscanner range is increased to cover large surface corrugations, then the measurement capability on rough samples is improved, but the device complexity increases
Solution Approach 1:
The vertical scanning function is segmented between two independent components: the nanoscanner handles fine-scale vertical movements for force control, while the additional actuator handles coarse-scale height adjustments for rough surface compensation. This segmentation allows each component to operate within its optimal range, resolving the contradiction between measurement capability and device complexity.
Solution Approach 2:
The additional actuator is integrated into the existing nanoscanner structure, with the nanoscanner effectively nested within the larger actuation system. The additional actuator provides the outer layer of height adjustment, while the nanoscanner provides the inner layer of precise force control, creating a nested hierarchical structure that expands capability without proportionally increasing complexity.
2Reliability
If the nanoscanner extension range is increased to accommodate large surface corrugations, then the reliability of maintaining constant tip-sample force is improved, but the device complexity increases
Solution Approach 1:
The force maintenance function is segmented between the nanoscanner (fine adjustments) and the additional actuator (coarse adjustments). This segmentation ensures that the constant tip-sample force is maintained through coordinated action of both components, improving reliability without requiring a single oversized nanoscanner that would increase complexity.
Solution Approach 2:
The system employs feedback control where the cantilever deflection signal is continuously monitored and used to control both the nanoscanner and additional actuator. This feedback mechanism ensures reliable constant force maintenance by dynamically adjusting the vertical position based on real-time interaction force measurements, resolving the reliability-complexity contradiction.
3Measurement precision
If additional actuators are added to adjust probe level, then the measurement accuracy on rough samples is improved, but the device complexity increases
Solution Approach 1:
The height adjustment function is segmented into coarse adjustment (additional actuator) and fine adjustment (nanoscanner). This segmentation enables high measurement precision by ensuring that each component operates in its optimal performance range, while the modular segmented architecture manages complexity through functional decomposition.
Solution Approach 2:
The additional actuator serves multiple functions: it adjusts the probe level for rough surface compensation, maintains optimal operating range of the nanoscanner, and works in coordination with the nanoscanner for both imaging and indentation measurements. This multi-functionality justifies the added complexity by delivering comprehensive measurement capabilities across diverse sample types.
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 indentation testing and imaging of rough samples by maintaining a constant probe-sample interaction force and optimal angle, preventing loss of contact and ensuring precise measurements across varying sample topography.
Implementation Method 1
nanoscanner, in particular piezo elements, usually exhibit a range of motion that can vary between 5 μm and 100 μm depending on manufacturer design
Implementation Method 2
adjusting a level of the probe along the first direction by means of an additional actuator
Data Source
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AI summary
The present invention relates to a method for controlling a scanning probe microscope having a probe (2) with a tip (21) for interacting with a sample (4), and a nanoscanner (1) for retaining the sample (4) or the probe (2), comprising the steps of monitoring the extension of the piezo element (1) along a first direction (R) along which the tip (21) is moved towards the sample (4), and adjusting the level of the probe (2) along the first direction (R) by means of an additional actuator (3), when the nanoscanner (1) exhibits an extension below or above a threshold value. The invention further relates to a device(100) for controlling a scanning probe microscope.