Flexible Plasmonic Nanocups via Rigid Substrate Inversion
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Solution Overview
Problem
Existing methods for fabricating plasmonic nanostructures on rigid substrates are limited by compatibility issues with thermal treatment and lack of designer freedom, resulting in low aspect ratio and symmetric shapes, which are not suitable for flexible implantable and sensing applications.
Innovation Solution
A method involving etching silicon substrates to form nanostructures, oxidizing them, depositing metallic layers, reflowing to form bulbs, and transferring these structures onto flexible substrates, allowing for precise control of shape, embedding depth, and metal placement between nanostructures, enabling high-aspect-ratio nanocups with customizable shapes and self-aligned functionalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plasmonic nanostructures are fabricated on rigid substrates using existing methods, then the fabrication process is straightforward, but the aspect ratio is low and the shapes are symmetric and limited
Solution Approach 1:
The patent inverts the conventional fabrication approach by first creating high-aspect-ratio silicon nanostructures on a rigid substrate, then transferring them to a flexible substrate. This inversion allows the rigid substrate to provide fabrication precision while the flexible substrate provides mechanical flexibility, resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The patent uses a flexible substrate as an intermediary carrier that receives the pre-fabricated silicon nanostructures. This intermediary allows the nanostructures to be formed with high precision on a rigid substrate first, then transferred to achieve both high aspect ratio and mechanical flexibility, resolving the contradiction between fabrication simplicity and shape control precision.
2Manufacturing precision
If thermal treatment is applied during fabrication, then metal layer reflow and bulb formation are achieved, but compatibility issues with flexible substrates arise
Solution Approach 1:
The patent segments the fabrication process into two distinct stages: (1) forming silicon nanostructures and depositing metal layers on a rigid substrate where thermal treatment can be applied, and (2) transferring the complete structure to a flexible substrate. This segmentation allows thermal treatment to be applied where compatible, while still achieving flexible substrate compatibility in the final product.
Solution Approach 2:
The patent performs preliminary actions of silicon nanostructure formation, metal layer deposition, and thermal reflow on a rigid substrate before transferring to the flexible substrate. This preliminary action on a compatible substrate enables precise metal placement control while avoiding compatibility issues during the thermal treatment stage.
3Ease of manufacture
If conventional fabrication methods are used on rigid substrates, then the process is well-established, but designer freedom and customization are limited
Solution Approach 1:
The flexible substrate acts as an intermediary that enables designer freedom by allowing post-fabrication manipulation. After the nanostructures are formed with high precision using well-established methods on a rigid substrate, the flexible substrate allows for stretching, compressing, and custom positioning, providing designer freedom while maintaining process establishment.
Solution Approach 2:
The patent introduces dynamics by using a flexible substrate that can be stretched, compressed, and manipulated after fabrication. This dynamic capability provides designer freedom for customization and reconfiguration while the initial fabrication uses well-established static processes on a rigid substrate.
4Reliability
If high-aspect-ratio nanocups are fabricated, then sensing performance is improved, but fabrication complexity increases
Solution Approach 1:
The patent inverts the transfer process by first creating high-aspect-ratio silicon nanostructures on a rigid substrate using standard lithography and etching, then transferring them to a flexible substrate. This inversion achieves high sensing performance through high aspect ratio while managing fabrication complexity by using well-established processes in the initial stage.
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 the fabrication of high-aspect-ratio plasmonic nanostructures with customizable shapes and self-aligned functionalization on flexible substrates, suitable for implantable and sensing applications, overcoming limitations of rigid substrates and achieving precise control over nanostructure placement and distance.
Implementation Method 1
reflowing the metallic layer to form metallic bulbs on a top section of the silicon oxide nanostructures
Implementation Method 2
etching a silicon substrate to form silicon nanostructures on top of the silicon substrate
Implementation Method 3
oxidizing the silicon nanostructures to form silicon oxide nanostructures
Implementation Method 4
depositing a metallic layer on the silicon oxide nanostructures
Data Source
AI summary
Methods for fabricating flexible substrate nanostructured devices are disclosed. The nanostructures comprise nano-pillars and metallic bulbs or nano-apertures. The nanostructures can be functionalized to detect biological entities. The flexible substrates can be rolled into cylindrical tubes for detection of fluidic samples.