Microstructured Polymer Devices Primer Layer
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Solution Overview
Problem
Microfluidic devices face challenges in achieving effective conductivity due to the presence of high boiling point humectant solvents, which require higher sintering temperatures, potentially damaging thermoplastic substrates and resulting in lower and more variable conductivity.
Innovation Solution
A primer layer is introduced to absorb non-volatile components of the humectant solvents, allowing for lower temperature sintering and improving conductivity by absorbing these components, thus enhancing the conductivity of the conductive liquid and reducing substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high boiling point polyols are used as humectants in conductive liquid, then the ink reliability is improved by preventing premature drying, but the sintering temperature must be increased which may damage thermoplastic substrates and results in lower conductivity
Solution Approach 1:
A primer layer comprising hydrophilic polymer is introduced as an intermediary between the thermoplastic substrate and the conductive liquid containing high boiling point polyols. This primer layer selectively absorbs the humectant solvents through hydrogen bonding, preventing them from remaining in the final sintered electrode structure. The primer acts as a mediator that allows the use of reliable humectants during jetting while eliminating their harmful effects during sintering, enabling lower temperature processing that protects the thermoplastic substrate.
2Reliability
If high boiling point polyols are used as humectants, then drying prevention is improved, but conductivity becomes lower and more variable due to impeded conductive pathways
Solution Approach 1:
The hydrophilic polymer primer serves as an intermediary absorption medium that selectively removes humectant solvents from the conductive liquid. By absorbing these non-volatile components through hydrogen bonding interactions, the primer ensures that the sintered electrode structure contains minimal residual solvent, thereby maintaining consistent and high conductivity. This intermediary action decouples the need for humectants during jetting from their detrimental effect on conductivity.
3Loss of substance
If higher sintering temperatures are applied to evaporate humectant solvents, then solvent removal is improved, but energy input increases and thermoplastic substrates may be damaged
Solution Approach 1:
The primer layer performs preliminary absorption of humectant solvents before the sintering process. By pre-absorbing these solvents through hydrogen bonding during the coating and drying stages, the primer eliminates the need for high temperature solvent evaporation during sintering. This preliminary action protects the thermoplastic substrate from thermal damage while still achieving complete solvent removal, as the absorbed solvents are retained in the primer layer rather than requiring thermal evaporation.
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 primer layer effectively absorbs humectant solvents, enabling sintering at lower temperatures, improving conductivity, and preventing substrate damage, resulting in more reliable and consistent electrode formation in microfluidic devices.
Implementation Method 1
The primer layer absorbs the non-volatile components of the humectant organic solvents in which the electrically conductive material of the conductive liquid is dispersed
Implementation Method 2
The conductive liquid is allowed to flow throughout the microfluidic channel by capillary action to form the planar electrode structure
Data Source
Figure 1A~1G
Figure 2A~2C
Figure 3~4
AI summary
A method of manufacturing a device with a planar electrode structure, the method comprising: (a) forming a microfluidic channel on a substrate; (b) applying a primer layer to at least part of the microfluidic channel, (c) applying a conductive liquid to the microfluidic channel, the conductive liquid comprising electrically conductive particles dispersed in a carrier medium, the carrier medium including a solvent; (d) allowing the conductive liquid to flow throughout the microfluidic channel by capillary action to form the planar electrode structure; and (e) evaporating the solvent from the carrier medium, is described. Devices obtainable using the method and their applications are also described.