Triboelectric Sensor Film via Subzero Drop Casting
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Solution Overview
Problem
Conventional methods for depositing polymeric films on substrates for triboelectric applications often result in non-uniform films with low surface area, leading to suboptimal triboelectric performance, and are either costly or lack scalability due to the need for complex surface structuring techniques.
Innovation Solution
A triboelectric sensor is formed by dissolving a triboelectric polymer in a solution and drop casting it onto an electrode layer at a temperature below 0°C, creating a first triboelectric layer with a surface roughness of at least 0.3 microns, which enhances the triboelectric response through increased surface area and friction coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vacuum evaporation is used to deposit polymer on substrate, then the deposition process is simple, but the deposition may be non-uniform and requires finding suitable solvent/polymer matches with specific boiling point constraints
Solution Approach 1:
The patent changes the temperature parameter during drop casting by using pre-cooled substrates (below 0°C) to control the deposition process. This temperature control allows the polymer solution to form uniform films with consistent morphology, resolving the uniformity issue while maintaining the simplicity of the drop casting method.
2Manufacturing precision
If spin coating is used to achieve uniform material layer, then uniformity is improved, but high spin speeds are required which demand high mixture viscosity
Solution Approach 1:
The patent replaces the high-speed mechanical spin coating process with a static drop casting method. By substituting the mechanical spinning action with a controlled droplet deposition process on pre-cooled substrates, uniform films are formed without requiring high spin speeds or specific viscosity conditions.
3Area of stationary object
If dip coating is used to cover substrate entirely, then complete coverage is achieved, but substrate is coated on both sides wasting active material and thickness control is difficult
Solution Approach 1:
The patent applies coating only to the required area (one side of the substrate) using drop casting, rather than coating both sides as in dip coating. This localized application approach eliminates material waste while achieving complete coverage of the functional surface, and allows precise control of film thickness through solution concentration and droplet volume.
4Shape
If Breath-figure technique is used to form porous film, then porous structure is created in upper layer, but technique works only in very high humidity conditions and with nonpolar solvents
Solution Approach 1:
The patent changes the temperature parameter (using pre-cooled substrates below 0°C) to induce porous structure formation during drop casting. This approach creates porous films without requiring very high humidity conditions or being restricted to nonpolar solvents, thereby expanding the method's applicability to various solvent systems including polar solvents.
5Productivity
If spray coating is used to deposit polymer, then material can be sprayed onto substrate, but very low polymer concentrations are required due to small nozzle size limiting film thickness and requiring large solvent volumes
Solution Approach 1:
The patent extracts the nozzle constraint by using direct drop casting instead of spray coating through small nozzles. This allows the use of higher polymer concentrations in the solution since the material is deposited as discrete droplets rather than being forced through narrow spray channels, enabling formation of sufficiently thick films without requiring large volumes of solvent.
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 method produces triboelectric sensors with significantly improved output voltage and surface roughness, offering enhanced triboelectric performance, reduced manufacturing costs, and the ability to form complex, arbitrary-shaped films, making them suitable for various applications.
Implementation Method 1
drop casting the solution onto the electrode layer at a temperature below 0 degrees Celsius (°C) to form the first triboelectric layer
Implementation Method 2
The first triboelectric layer has a surface roughness of at least 0.3 micron (μm) as determined by an optical profiler... which enhances the triboelectric response through increased surface area and friction coefficient
Data Source
Figure 1
Figure 2~3
Figure 4A~5
AI summary
A triboelectric sensor includes a substrate layer, at least one electrode layer, and at least a first triboelectric layer including a triboelectric polymer. The first triboelectric layer is applied to the at least one electrode layer by a process including: dissolving the triboelectric polymer in a solution; and drop casting the solution onto the electrode layer at a temperature below 0 degrees Celsius (°C) to form the first triboelectric layer. The first triboelectric layer has a surface roughness of at least 0.3 micron (µm) as determined by an optical profiler.