Stretchable Electrode Patterning on Low-Adhesion PDMS Substrates
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Solution Overview
Problem
Stretchable substrates, such as PDMS, exhibit high surface stability, leading to low adhesion issues that hinder the application of photoresist layers and subsequent photolithography processes, limiting the ability to pattern electrodes effectively.
Innovation Solution
A method involving UV-ozone treatment to form hydrophilic groups on the substrate surface, followed by coating an adhesion-enhancing material like polyvinylpyrrolidone (PVP) to improve adhesion, allowing for the formation of photoresist layers and direct patterning through photolithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photolithography process is applied directly to a stretchable substrate, then electrode patterning can be achieved, but the process cannot be performed due to low adhesion of photoresist layer to the substrate surface
Solution Approach 1:
An adhesion enhancing layer is introduced as an intermediary between the stretchable substrate and the photoresist layer. This layer contains adhesion enhancing materials that form strong bonds with both the substrate surface and the photoresist, enabling successful photolithography processing on stretchable substrates without direct adhesion problems between photoresist and substrate
Solution Approach 2:
The surface properties of the stretchable substrate are modified through UV-ozone treatment, which changes the surface energy and chemical composition to create hydrophilic groups. This parameter change in surface properties enables better adhesion of the adhesion enhancing layer and subsequent photoresist layer
2Reliability
If the surface of the stretchable substrate is modified to improve adhesion, then photoresist layer adhesion is enhanced, but the substrate surface stability is reduced
Solution Approach 1:
Surface modification is applied locally only to the regions where adhesion is needed, rather than changing the entire substrate. The UV-ozone treatment and adhesion enhancing layer are confined to the patterned areas, allowing the bulk substrate to maintain its original stable properties while achieving local adhesion enhancement for photolithography
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 enhances the adhesive force between the substrate and the photoresist layer, enabling successful photolithography on stretchable substrates and facilitating the fabrication of stretchable electrodes with desired patterns for various applications.
Implementation Method 1
forming a hydrophilic group on a surface of a stretchable substrate by UV-ozone treatment
Implementation Method 2
a carbon chain included in the adhesion enhancing material forms ether bonding (R—O—R) with a hydrophilic group formed on the surface of the stretchable substrate
Data Source
AI summary
Disclosed are a method of directly patterning a stretchable substrate; and a stretchable electrode fabricated by the method. More particularly, the method of directly patterning a stretchable substrate includes: forming a hydrophilic group on a surface of a stretchable substrate by UV-ozone treatment; forming at least one layer to be etched on the hydrophilic group-formed stretchable substrate, wherein the at least one layer to be etched includes an adhesion enhancing material; forming a photoresist layer on the at least one layer to be etched; exposing the photoresist layer; and patterning the at least one layer to be etched using the exposed photoresist layer, wherein a carbon chain included in the adhesion enhancing material forms ether bonding (R—O—R) with a hydrophilic group formed on the surface of the stretchable substrate.