Tunable Hierarchical Wrinkle Patterns via Compressive Strain
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Solution Overview
Problem
Current methods for fabricating micro/nano scale hierarchical structures are limited by high cost, low scalability, and inability to tune or modify the hierarchy after fabrication, preventing the creation of tunable 'smart' sensors and devices.
Innovation Solution
A scalable and affordable process for fabricating tunable hierarchical structures is developed by performing wrinkling of pre-patterned surfaces, where the hierarchy is tuned via applied compressive strain, using a bilayer system with a thin hard film on a soft compliant base, and controlling parameters through a model-driven design and precise tooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple substantially different fabrication processes are used to fabricate hierarchical micro/nano structures, then the structure-property relationship can be controlled, but the manufacturing cost increases and scalability decreases
Solution Approach 1:
The patent combines multiple fabrication steps into a single wrinkling process. By depositing a thin film on a patterned substrate and applying compression, the process simultaneously creates hierarchical structures with multiple length scales, eliminating the need for separate fabrication processes for each structural level and thereby reducing cost and improving scalability.
Solution Approach 2:
The patent uses a pre-patterned substrate as the basis for hierarchical structure formation. The substrate pattern serves as a template that guides the subsequent wrinkling process, allowing complex hierarchical structures to be formed through a single compression step rather than requiring multiple sequential fabrication processes.
2Manufacturing precision
If hierarchical micro/nano structures are fabricated using conventional processes, then the structures can be manufactured, but the hierarchy cannot be tuned or modified after fabrication
Solution Approach 1:
The patent creates dynamically tunable hierarchical structures where the compression applied during the wrinkling process can be varied to control the final structure. By adjusting compression parameters such as magnitude and duration, the hierarchy can be tuned after the basic structure is formed, enabling modification of structural properties without requiring remanufacturing.
Solution Approach 2:
The patent demonstrates that hierarchical structures can be tuned by changing process parameters during the wrinkling process. By varying compression magnitude, duration, and rate, the hierarchy characteristics such as feature size, spacing, and depth can be adjusted, providing post-fabrication tunability while maintaining manufacturing precision.
3Shape
If conventional wrinkling processes are used to fabricate hierarchical patterns, then periodic patterns can be formed, but the patterns are limited to a single period and cannot be tuned
Solution Approach 1:
The patent segments the hierarchical structure into multiple distinct periodic patterns with different lengths scales. By using a pre-patterned substrate with specific features and controlling the wrinkling process, the technique creates multiple periodic patterns simultaneously, each with tunable characteristics, rather than being limited to a single periodic structure.
Solution Approach 2:
The patent uses a pre-patterned substrate that establishes the basis for multiple periodic patterns. The pre-pattern features serve as nucleation points that guide the formation of different periodic structures during compression, enabling the creation of tunable hierarchical patterns with multiple length scales from a single process.
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 process allows for predictive design and fabrication of hierarchical patterns at a fraction of the cost of existing methods, enabling deterministic tuning of the hierarchical form and application in devices like tunable optical sensors and microfluidic circuits.
Implementation Method 1
Wrinkled patterns are formed on supported thin films as a result of buckling-based instabilities and the mechanism is similar to Euler buckling of beams under compressive loads.
Implementation Method 2
Wrinkled patterns are formed on supported thin films as a result of buckling-based instabilities and the mechanism is similar to Euler buckling of beams under compressive loads.
Implementation Method 3
mismatch in the elastic moduli of the film and the base 12 with the film being stiffer than the base
Data Source
AI summary
This invention relates to the low-cost manufacture of a tunable physical topographic pattern and more particularly to the manufacture of micro and nano scale hierarchical periodic wrinkle patterns that are generated upon compression of supported thin films. Disclosed herein is (i) a composite material with tunable hierarchical wrinkle patterns, wherein the composite material comprises a stretched and pre-patterned base layer and a thin film that is conformally attached to the pre-patterned surface of the base layer, (ii) a method of fabricating the pre-patterned base via pattern replication, and (iii) a method of fabricating tunable hierarchical wrinkle patterns, wherein the pattern can be deterministically switched across the hierarchical and non-hierarchical states via strain control.