Nanopositioner Piezo Actuator Layout for Cryogenic Repeatability
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Solution Overview
Problem
Nanopositioners face challenges in cryogenic environments due to high heat generation and premature wear, limiting positional repeatability to micrometer levels, which are unsuitable for precise applications.
Innovation Solution
A nanopositioner design with a base and carrier system, incorporating a variable area capacitive position sensor and a removable stator, uses low-capacitance piezoelectric actuators to achieve nanometer-level positional repeatability by minimizing heat and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional nanopositioners use large piezo stacks with high capacitance (5 to 10 microfarads) to achieve motion, then they can provide sufficient driving force, but they generate an undesirable amount of heat in cryogenic environments
Solution Approach 1:
The patent divides the piezo stack into multiple smaller piezo elements (e.g., four 1mm diameter elements instead of one large element) that collectively provide the same driving force. This segmentation reduces the total capacitance from 5-10 microfarads to a lower value, thereby reducing heat generation while maintaining sufficient driving force through the combined output of multiple elements.
Solution Approach 2:
The patent employs a nested configuration where multiple piezo elements are arranged in a compact, space-efficient manner within the actuator assembly. This allows the use of multiple smaller piezo elements that collectively provide the required driving force while occupying minimal space and generating less heat compared to a single large piezo stack.
2Force
If conventional nanopositioners use large piezo stacks to achieve motion, then they can provide sufficient driving force, but they reduce positional repeatability to micrometer levels
Solution Approach 1:
By using multiple smaller piezo elements instead of one large element, the patent achieves both sufficient driving force through combined output and improved positional repeatability at the nanometer level. The segmented configuration allows for better control and reduced mechanical stress, enhancing precision.
3Power
If conventional nanopositioners operate with high currents on the order of 10s of milliamps, then they can drive the piezo stacks, but they generate excessive heat in cryogenic environments
Solution Approach 1:
The patent segments the driving power across multiple smaller piezo elements, each requiring lower current. The combined power output remains sufficient for driving the nanopositioner, while the distributed current load reduces heat generation compared to using a single large piezo stack requiring high currents of 10s of milliamps.
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 design provides positional repeatability on the order of 200 nanometers, significantly improving performance over conventional nanopositioners, making it suitable for cryogenic environments and other applications.
Implementation Method 1
slip-stick (or stick-slip) piezoelectric actuators that provide a motive force according to a slip-stick cycle
Implementation Method 2
The sense electrode and the set of drive electrodes at least partially establish a variable area capacitive position sensor
Data Source
AI summary
A nanopositioner 10 including a base 12 including a base plate 18 carrying a set of base bearings 22, a carrier 14 movably carried with respect to the base 12 and including a carrier plate 56 carrying a set of carrier bearings 58 operatively coupled to the set of base bearings 22. The nanopositioner 10 may include a variable area capacitive position sensor, and/or an actuator 16 operatively coupling the carrier 14 to the base 12 and including an armature 100 fixed with respect to the carrier 14 and a stator 98 removably coupled to the base 12 to facilitate removal and replacement of at least a portion of the stator 98. Also disclosed are a method of producing a nanopositioner, and a piezoelectric actuator 16 that may be used with a nanopositioner.