Primer-Coated Microfluidic Electrodes for Precise Channel Alignment
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Solution Overview
Problem
Existing microfluidic devices face challenges in accurately and precisely placing electrodes relative to fluid channels, leading to variations in electric field magnitude and potential electrical shorts, especially when using thermoplastic substrates which can be damaged by high sintering temperatures required for conductive ink drying.
Innovation Solution
A microfluidic device with a primer layer comprising organic polymers such as vinyl lactam, cellulose ether, or polyvinyl alcohol, combined with a porous particulate material, is used to absorb humectant solvents from conductive ink, allowing for lower temperature sintering and improved conductivity and edge definition of the conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high sintering temperature is used to dry conductive ink, then conductivity of the conductive layer is improved, but thermoplastic substrate is damaged
Solution Approach 1:
A primer layer comprising organic polymers (vinyl lactam, cellulose ether, or polyvinyl alcohol) and porous particulate material is applied to the thermoplastic substrate before depositing conductive ink. This primer layer acts as an intermediary that absorbs humectant solvents during lower temperature sintering, enabling conductive layer formation without exposing the thermoplastic substrate to damaging high temperatures.
Solution Approach 2:
The invention changes the sintering temperature parameter from high temperature (required for conventional conductive ink drying) to lower temperature (compatible with thermoplastic substrates). This is achieved by modifying the ink composition to use volatile solvents that evaporate at lower temperatures, and by using a primer layer to facilitate complete solvent removal at these reduced temperatures.
2Ease of manufacture
If conventional conductive ink is used, then ease of manufacture is improved, but manufacturing precision of electrode placement deteriorates due to poor edge definition and voids
Solution Approach 1:
The conductive system uses a composite structure consisting of a primer layer (organic polymer + porous particulate material) combined with a conductive ink layer. This composite approach provides both ease of manufacture through ink jet printing and high manufacturing precision through improved edge definition and void elimination, as the primer layer supports uniform ink distribution and complete solvent evaporation.
3Ease of operation
If high boiling point polyols are used as solvents in conductive ink, then ease of operation during jetting is improved, but sintering temperature requirement increases
Solution Approach 1:
The invention changes the solvent parameter from high boiling point polyols to volatile solvents with lower boiling points. This allows the conductive ink to be jetted effectively (maintaining ease of operation) while enabling complete solvent evaporation at lower sintering temperatures that are compatible with thermoplastic substrates.
Solution Approach 2:
The primer layer serves as an intermediary that facilitates complete removal of volatile solvents from the conductive ink at lower temperatures. By providing a porous structure and appropriate chemical interactions, the primer ensures thorough solvent evaporation even at reduced temperatures, maintaining conductive layer quality without requiring high energy input.
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 approach results in more uniform and reproducible conductive layers with better-defined edges and fewer voids, reducing the risk of electrical shorts and enhancing the precision of electrode placement, while avoiding damage to thermoplastic substrates.
Implementation Method 1
the primer layer comprises (i) an organic polymer selected from the group consisting of: (a) a homopolymer or copolymer including a vinyl lactam repeating unit; (b) a cellulose ether, (c) polyvinyl alcohol; and (d) unmodified or modified gelatin; (ii) a porous particulate material, the organic polymer being dispersed in the porous particulate material
Data Source
AI summary
A microfluidic device comprising: a substrate having a microfluidic channel, an electrically conductive feature comprising an electrically conductive layer arranged on a primer layer and positioned with reference to the microfluidic channel, wherein the primer layer comprises: (i) an organic polymer selected from the group consisting of. (a) a homopolymer or copolymer including a vinyl lactam repeating unit, (b) a cellulose ether; (c) polyvinyl alcohol; and (d) unmodified or modified gelatin; and (ii) a porous particulate material, the organic polymer being dispersed in the porous particulate material, is provided. Methods for manufacturing the microfluidic devices and their use in a number of applications are also provided.