MEMS Nanoindenter Chip with Reference Probe for Accurate Measurement
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Solution Overview
Problem
Nanoindentation systems face challenges in accurately measuring mechanical properties of hard materials due to low frame stiffness and thermal drift, which are exacerbated by the large size of the nanoindentation system compared to the small indentation depth, requiring sophisticated and expensive equipment.
Innovation Solution
A MEMS-based nanoindenter chip with an indenter probe and a reference probe on the same chip, where the reference probe measures the indentation depth independently of the frame stiffness, reducing thermal drift and eliminating its influence on measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large-scale nanoindentation system is used to measure small indentation depths, then measurement capability is achieved, but thermal drift errors increase significantly
Solution Approach 1:
A reference probe is introduced as an intermediary element that contacts the specimen surface alongside the indenter probe. The reference probe serves as a mediator to measure surface position and indentation depth, isolating the measurement from thermal drift affecting the large-scale system frame. This intermediary approach allows accurate local measurement without being influenced by global thermal expansion.
Solution Approach 2:
The measurement function is extracted from the large-scale nanoindentation system frame and transferred to a compact MEMS-based measurement sensor. By separating the measurement capability from the bulky system structure, the patent eliminates the thermal drift problem inherent in large-scale systems while maintaining the ability to measure sub-micrometer indentation depths.
2Measurement precision
If the nanoindentation system frame is made stiff to accurately measure hard materials, then measurement accuracy improves, but frame stiffness becomes non-constant across the working area
Solution Approach 1:
The measurement sensor is extracted from the large-scale system and implemented as a compact MEMS device integrated directly on the chip. This extraction eliminates the need for a large stiff frame, as the measurement is performed locally by the MEMS sensor which maintains constant stiffness across its small working area.
Solution Approach 2:
The patent transitions from a large-scale three-dimensional system with varying frame stiffness to a compact planar MEMS structure. By reducing the measurement to a two-dimensional chip scale, the system achieves uniform stiffness characteristics across the entire working area, eliminating the stiffness variation problem of large frames.
3Object-affected harmful factors
If MEMS-based measurement sensors are used to reduce size and thermal drift, then thermal drift is reduced, but frame stiffness becomes too low for accurate measurement
Solution Approach 1:
The patent combines the indenter probe and reference probe onto a single MEMS chip, merging multiple measurement functions into one integrated device. This merging allows the system to achieve both low thermal drift (through compact size) and sufficient measurement capability (through integrated dual-probe design) simultaneously.
Solution Approach 2:
The MEMS chip is designed with multi-functionality, serving as both the indenter mechanism and the reference measurement system. By making the chip perform multiple functions, the patent eliminates the need for separate high-stiffness external framing structures, as the chip itself provides both the mechanical function and the measurement function with appropriate stiffness characteristics.
4Measurement precision
If a reference probe is added to eliminate frame stiffness influence, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The indenter probe and reference probe are merged onto a single MEMS chip, reducing device complexity compared to having separate external probes. This integration simplifies the overall system architecture while maintaining the dual-probe measurement capability needed to eliminate frame stiffness influence.
Solution Approach 2:
The MEMS chip serves multiple functions: it provides both the indenter probe for applying load and the reference probe for measuring surface position. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall device complexity despite the addition of reference measurement capability.
Data Source
AI summary
A MEMS-nanoindenter chip performs nanoindentation on a specimen. The MEMS-nanoindenter chip has an intender probe joined with an indenter tip. The indenter tip indents into the specimen. A reference probe is joined with a reference tip, the reference tip touches the specimen. Sensing capabilities are provided to measure the position of the indenter probe relative to the reference probe. The MEMS-nanoindenter chip enables highly accurate measurements since the frame stiffness is not part of the measurement chain any more. Furthermore, thermal drift during the nanoindentation is considerably reduced.