3D Polymer-Metal Microstructure via Stereolithography and Electroless Plating

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Solution Overview

Problem

Existing methods for producing three-dimensional polymer-metal microstructures are complex, require multiple steps, and can denature biomolecules, limiting their application in forming arbitrary steric structures and site-specific metal coatings for devices like nanoneedles and drug delivery devices.

Innovation Solution

A method using stereolithography to create arbitrary steric polymer structures, followed by dipping in aqueous solutions of metal-containing nanoparticles with reactive groups, allowing for site-specific metal layer formation at ordinary temperature and atmospheric pressure without denaturing biomolecules, using reactive groups that can be protected to prevent wastage and enable the use of metals like gold, silver, and magnetic metals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional metal coating methods (sputtering, vapor deposition, metal plating) are used through a mask, then metal layers can be formed on polymer structures, but the process requires a large number of steps, large-sized apparatuses, and increases installation space and cost

Engineering Contradiction:
Improvemetal layer formation precisionVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical metal coating methods (sputtering, vapor deposition, metal plating) with a chemical approach using electroless plating. This substitution eliminates the need for large-sized vacuum apparatuses and complex mask alignment systems, significantly reducing device complexity and installation space while maintaining metal layer formation capability

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary chemical process (electroless plating using reducing agents) as a mediator between the polymer structure and metal deposition. This intermediary approach allows metal layers to be formed through chemical reduction reactions in solution, avoiding the need for complex physical vapor deposition equipment and mask-based patterning systems

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If conventional metal coating methods are used, then metal layers can be deposited, but it may be impossible to apply this process to non-planar substrates and form three-dimensional structures with arbitrary steric structure

Engineering Contradiction:
Improvemetal layer deposition accuracyVSAvoidsubstrate shape adaptability
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameter of metal deposition from physical vapor phase (requiring planar substrates for mask alignment) to chemical solution phase (electroless plating). This parameter change allows the metal coating process to conform to arbitrary three-dimensional surfaces, enabling formation of complex steric structures including nanoneedles, helices, and other non-planar geometries

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of forming metal layers on planar substrates and then attempting to create three-dimensional structures, the patent inverts the approach by first forming arbitrary three-dimensional polymer structures and then applying metal coating. This inversion enables the substrate geometry to dictate the final device architecture rather than being constrained by planar processing requirements

Inventive Principle:
Principle #13The other way round (Inversion)

3Manufacturing precision

If electroless plating is used to form metal films on polymer structures, then metal coating can be achieved, but the structure must be dipped in acid or alkali solution in a heating atmosphere which denatures biomolecules

Engineering Contradiction:
Improvemetal film formation precisionVSAvoidbiomolecule denaturation
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the operational parameters of the electroless plating process from harsh conditions (acidic/alkaline solutions, elevated temperatures) to mild conditions (neutral pH, room temperature). This parameter modification eliminates biomolecule denaturation while maintaining the metal deposition capability through alternative chemistry (using reducing agents like ascorbic acid or hydrazine in neutral buffers)

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs disposable, biocompatible reducing agents (such as ascorbic acid, citric acid, or hydrazine) that can be easily removed or degraded after the plating process. These short-lived chemical intermediates enable metal deposition under mild conditions and can be washed away without affecting the final device or remaining biomolecules

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

4Manufacturing precision

If electron donors are added to photocurable resin or reducing agents are used after forming polymer structures, then metal films can be deposited on polymer structures, but it may be impossible to form metal films of different kinds depending on the site of the polymer structure

Engineering Contradiction:
Improvemetal film deposition controlVSAvoidsite-specific metal coating capability
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by introducing spatially varying electron donor concentrations or types within the photocurable resin before stereolithography. This creates regions with different metal-coating affinities, enabling site-specific deposition of different metal films on different parts of the same polymer structure. Alternatively, sequential dipping in different metal salt solutions allows different metals to be deposited on different sites based on local reducing agent distribution

Inventive Principle:
Principle #3Local quality

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 method simplifies the production of three-dimensional polymer-metal microstructures with arbitrary steric shapes and site-specific metal layers, preventing biomolecule denaturation and enabling efficient fabrication of devices such as nanoneedles and drug delivery systems with precise metal distribution.

Implementation Method 1

a fine polymer structure having an arbitrary steric structure is constituted by stereolithography using a photocurable resin

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

bind a reactive group X on the polymer structure to a reactive group X' on a metal-containing nanoparticle, thereby forming a metal-containing layer on the polymer structure

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentEP2586596B1Three-dimensional polymer-metal composite microstructure and method for producing same
Publication Date: 2017.08.09 THE JAPAN SCI & TECH AGENCY
  • EP2586596B1 patent drawingFigure 1~2
  • EP2586596B1 patent drawingFigure 3~4
  • EP2586596B1 patent drawingFigure 5

AI summary

Disclosed is a method for producing a three-dimensional polymer-metal complex microstructure including forming a polymer structure by stereolithography using a photocurable resin having a reactive group X and dipping it in a liquid of a metal-containing nanoparticle having a reactive group X' which is bound to the reactive group X, thereby forming a metal-containing layer on the polymer structure through binding the reactive group X and the reactive group X'. According to this method, it is possible to produce a polymer-metal complex structure having a steric structure and to produce a three-dimensional polymer-metal complex microstructure which does not denature biomolecules in a metal complexation process.