Flexible Pressure Sensor Stress Management in Foldable Devices
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Solution Overview
Problem
Flexible and foldable electronic devices with pressure sensors face issues of delamination and cracking due to the stress on layers, particularly in the touch screen displays and pressure sensors.
Innovation Solution
The electronic device design incorporates a pressure sensor with a first and second electrode layer and a dielectric layer, where the electrode layers have varying flexibility and include recesses or gaps, and a flexible printed circuit board is used to distribute stress, preventing delamination and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the touch screen display and pressure sensor are made flexible to enable folding, then the device can be folded and portable, but delamination and cracking occur between layers due to stress
Solution Approach 1:
The pressure sensor is divided into multiple independent sensing regions (first pressure sensing region, second pressure sensing region, third pressure sensing region) separated by non-pressure-sensing regions. This segmentation allows each region to independently handle stress during folding, preventing crack propagation across the entire sensor while maintaining flexibility.
Solution Approach 2:
Different regions of the pressure sensor have different properties: sensing regions are designed to detect pressure, while non-pressure-sensing regions are designed to accommodate folding stress. The non-pressure-sensing regions act as stress relief zones that prevent delamination and cracking, allowing the sensing regions to maintain their functionality.
2Reliability
If rigid support structures are added to prevent delamination, then layer integrity is improved, but the device loses flexibility and cannot be folded
Solution Approach 1:
The pressure sensor uses a flexible substrate and thin-film structure that can bend and fold without breaking. The sensor layers are designed with appropriate thickness and material selection to maintain structural integrity during folding while remaining flexible enough to enable device portability.
Solution Approach 2:
By segmenting the pressure sensor into multiple regions with non-pressure-sensing areas, the structure can flex without creating continuous stress paths that would lead to cracking. The segmented design allows localized deformation without compromising overall layer integrity.
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 design effectively prevents delamination and cracking in the touch screen display and pressure sensor layers, enhancing the durability and reliability of flexible and foldable electronic devices.
Implementation Method 1
a dielectric layer arranged between the first electrode layer and the second electrode layer
Implementation Method 2
a first electrode layer formed in substantially parallel with the touch screen display; a second electrode layer spaced apart from the first electrode layer
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An electronic device according to various examples comprises: a housing, in an unfolded state, including a first surface facing a first direction and a second surface facing a second direction opposite to the first direction and including at least one flexible portion; a touch screen display arranged between the first surface and the second surface of the housing, exposed through the first surface of the housing, and when viewed from above the first surface, including at least one flexible portion at a position corresponding to the flexible portion of the housing; and a pressure sensor arranged between the touch screen display and the second surface of the housing, and when viewed from above the first surface, including at least one flexible portion at a position corresponding to the flexible portion of the housing. The pressure sensor comprises: a first electrode layer formed substantially in parallel to the touch screen display; a second electrode layer spaced apart from the first electrode layer in the second direction and formed substantially in parallel to the first electrode layer; and a dielectric layer arranged between the first electrode layer and the second electrode layer. Other examples are also possible.