Transparent Polyimide Tactile Sensor for Curved Surface Printing
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Solution Overview
Problem
Current polymer films used in printed electronics are unsuitable for forming tactile sensors on curved surfaces due to deformation issues during sintering, low transparency, and electrode formation defects, which limits their application in flexible and thin electronic devices.
Innovation Solution
A tactile sensor is developed using a polyimide thin film with a high glass transition temperature, high total light transmittance, and specific surface free energy, combined with a ferroelectric layer and electrodes, allowing for flexible and lightweight tactile sensing on both flat and curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional polymer films are used for tactile sensors, then the device can be manufactured, but the film deforms during sintering and cannot maintain shape on curved surfaces
Solution Approach 1:
The patent changes the glass transition temperature parameter of the polymer film from conventional low values to a high value of 250-310°C. This parameter change enables the film to maintain dimensional stability during sintering processes while remaining manufacturable on curved surfaces, resolving the contradiction between shape stability and ease of manufacture.
Solution Approach 2:
The patent employs a composite material system consisting of high glass transition temperature polyimide combined with ferroelectric materials (PVDF or P(VDF-TrFE)). This composite structure provides both the thermal stability needed for sintering and the piezoelectric functionality required for tactile sensing, enabling manufacture on curved surfaces without deformation.
2Illumination intensity
If conventional polymer films are used, then the device can be manufactured, but the transparency is low which limits aesthetic and functional applications
Solution Approach 1:
The patent changes the optical parameter of the polymer film by selecting materials with high total light transmittance of 80% or more. This parameter change improves transparency for aesthetic and functional applications while the specific material selection maintains suitable surface properties for reliable electrode formation through printing processes.
3Weight of moving object
If the polymer film is made thinner for flexibility, then the device becomes more flexible, but the film becomes more prone to deformation and defects
Solution Approach 1:
The patent changes multiple parameters of the polymer film including glass transition temperature (250-310°C), surface free energy (15-70 mJ/m²), and total light transmittance (80% or more). These parameter changes enable the film to maintain manufacturing precision with low defect rates even at thin dimensions, while achieving the flexibility required for wearable and conformable applications.
4Manufacturing precision
If high surface free energy materials are used for good electrode adhesion, then electrode formation improves, but the film becomes less transparent and more rigid
Solution Approach 1:
The patent optimizes the surface free energy parameter to a specific range of 15-70 mJ/m², with a polar component of 1.5 to 10 mJ/m². This parameter optimization provides sufficient adhesion for printed electrodes while maintaining high light transmittance of 80% or more, resolving the contradiction between electrode adhesion quality and transparency.
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 solution enables a high non-defective rate of tactile sensors that can detect subtle pressures and switch between on and off states effectively, suitable for various three-dimensional objects with improved transparency and reduced thickness.
Implementation Method 1
the polyimide thin film has a glass transition temperature of 250° C. or higher and 310° C. or lower
Implementation Method 2
a printed ferroelectric layer covering the first electrode; and a second electrode printed on the ferroelectric layer
Implementation Method 3
a total light transmittance of 80% or more
Implementation Method 4
a polar component of its surface free energy of 1.5 to 10 mJ/m2
Data Source
AI summary
A light, flexible, and tough thin film having high total light transmittance that can be formed on various three dimensional shapes, and also provides a stably driven tactile sensor, which is an electronic device having the switching function thereof, is provided. The tactile sensor is formed on a polyimide thin film having high total light transmittance, thermal resistance, and a polar component of surface free energy with a specific value, and has a switching device that emits a voltage signal which, through an electronic circuit for controlling noise, stably drives another device. This tactile sensor has a curved or flat surface and has a first electrode, a ferroelectric layer, and a second electrode formed over the polyimide thin film. The switching device as a tactile sensor can drive another device merely by a light touch with a finger, and can be manufactured at a high non-defective rate.