Multi-Actuator Nanopositioning for High-Speed Large-Range AFM Scanning
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Solution Overview
Problem
Current atomic force microscopy (AFM) systems face challenges in achieving high-speed imaging while maintaining large out-of-plane and lateral scan ranges, as increased mechanical bandwidth requires increased rigidity and reduced mass, leading to decreased scan ranges, limiting applications due to sample topography variations and feature sizes.
Innovation Solution
A multi-actuated system with cascaded serial nano positioners of different ranges and bandwidths, each controlled by separate controllers to compensate for coupled dynamics, enabling high-speed and large-range performance in all scan directions, decoupling performance along the X, Y, and Z axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If increased mechanical bandwidth is achieved through increased rigidity and reduced mass, then high-speed performance is improved, but scan range decreases
Solution Approach 1:
The scanner is divided into multiple independent actuation systems (lateral scan actuators and out-of-plane actuators) with different optimization goals. Each actuator can be independently designed for its specific function, allowing the lateral scan system to optimize for speed while the out-of-plane system optimizes for range, and vice versa.
Solution Approach 2:
The patent extends multi-actuation from single dimension (out-of-plane only in prior art) to three dimensions (X, Y, and Z axes). By adding lateral scan actuators to the multi-actuation architecture, the system achieves high-speed performance in lateral directions while maintaining large out-of-plane range through separate out-of-plane actuators.
2Adaptability or versatility
If out-of-plane scan range is increased to accommodate sample tilt and thickness variations, then adaptability is improved, but mechanical bandwidth decreases
Solution Approach 1:
The scanning function is segmented between lateral actuators (X, Y axes) and out-of-plane actuators (Z axis). The out-of-plane actuator is specifically designed with large travel range to accommodate sample tilt and thickness variations, while lateral actuators provide the high-speed scanning capability, allowing each subsystem to optimize for its primary function.
3Adaptability or versatility
If lateral scan range is increased to cover large sample features, then adaptability is improved, but mechanical bandwidth decreases
Solution Approach 1:
Lateral scanning is implemented through separate X and Y actuators that can be independently optimized. The lateral scan actuators are designed with high mechanical bandwidth to enable fast scanning across large sample areas, while the out-of-plane actuator handles the range requirements for sample topography variations.
4Speed
If multiple actuators are combined to achieve both range and speed, then performance is improved, but system complexity increases
Solution Approach 1:
The scanner uses segmented actuation where each axis (X, Y, Z) has dedicated actuators with specific optimization goals. This modular approach allows independent design and control of each actuator subsystem, simplifying the overall control architecture compared to attempting to optimize a single actuator for all requirements.
Solution Approach 2:
The patent generalizes multi-actuation from single-dimensional (out-of-plane only) to three-dimensional implementation. By distributing actuation functions across three spatial dimensions with dedicated actuators for each axis, the system achieves comprehensive performance optimization while maintaining manageable complexity through modular design.
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
The system behaves as a single actuator with large range and high speed, achieving 120 μm lateral and 6 μm out-of-plane range, capable of high-speed imaging with fully decoupled scan axes, enhancing the capability to capture high-resolution images at video rates and study dynamic nano-scale processes.
Implementation Method 1
the at least two nano positioners each contain a piezoelectric stack
Data Source
AI summary
Multi-actuator system. The system includes at least two nano positioners having different ranges and bandwidths located in cascaded serial form to contact and move an object. A control system employs data-based control design to combine the at least two nano positioners so as to apportion actuation responsibilities among the at least two nano positioners so as to compensate for their coupled dynamics while moving the object. It is preferred to provide a separate controller for controlling separately each of the at least two nano positioners. Parameters of the separate controllers may be determined by minimizing output error.