Flexible Pressure Sensor with Liquid Reservoir for Touch Screens
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Solution Overview
Problem
Existing pressure sensors, particularly those used in touch screens, face limitations in sensitivity and flexibility, as they are often made from rigid materials and lack the ability to accurately detect pressure with high reproducibility and precision.
Innovation Solution
A pressure sensor is developed using a flexible substrate made of electrically insulating plastic material, such as polyethylene naphthalate, with a liquid reservoir system that allows for high capacitance variation upon pressure application, enabling the creation of both capacitive and resistive type sensors with improved sensitivity and reproducibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pressure sensors are made from rigid materials for touch screen applications, then structural stability is improved, but flexibility and sensitivity are worsened
Solution Approach 1:
The patent employs a flexible substrate made of thin film material (such as polyethylene naphthalate or polyimide) with a thickness of 125 µm or less, which provides both structural stability and flexibility. This flexible substrate supports the pressure sensor elements while allowing the sensor to conform to curved surfaces and provide tactile feedback, resolving the contradiction between rigidity and flexibility.
Solution Approach 2:
The pressure sensor utilizes a composite structure combining conductive polymer material (such as polyethylenedioxythiophene or polyaniline) with the flexible substrate. This composite approach enables the sensor to maintain structural integrity while achieving both flexibility and pressure sensitivity, as the conductive polymer layers provide mechanical strength and electrical functionality simultaneously.
2Device complexity
If pressure sensors use simple detection mechanisms, then device complexity is reduced, but measurement precision and sensitivity are worsened
Solution Approach 1:
The patent replaces traditional mechanical pressure detection mechanisms with an electrical field-based detection system using conductive polymer layers. Instead of mechanical switches or levers, the sensor detects pressure through changes in electrical resistance or capacitance in the conductive polymer layers, achieving high precision with simpler, more reliable components.
Solution Approach 2:
The sensor achieves high measurement precision by detecting changes in electrical parameters (resistance, capacitance, or conductivity) of the conductive polymer material in response to pressure. This parameter-based detection method provides continuous, high-resolution pressure measurement without complex mechanical mechanisms, as the electrical properties of the polymer change predictably with applied pressure.
3Manufacturing precision
If pressure sensors are made with fixed detection thresholds, then manufacturing precision is improved, but adaptability to different pressure ranges is worsened
Solution Approach 1:
The patent implements a dynamic detection system where the sensor can adjust its operating parameters based on the applied pressure magnitude. The conductive polymer-based sensor provides a continuous range of electrical property changes that can be calibrated to detect different pressure thresholds, allowing the same sensor to adapt to various pressure ranges while maintaining manufacturing precision through consistent material properties.
Solution Approach 2:
The pressure sensor is designed with universal applicability across different pressure ranges by using the inherent non-linear electrical response of conductive polymers to pressure. The same sensor structure can be configured for different applications (from light touch to heavy pressure) by adjusting the measurement parameters and calibration, achieving both manufacturing precision and adaptability through a single versatile design.
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 provides a pressure sensor with enhanced sensitivity and short response time, allowing precise detection of pressure with high reproducibility, suitable for touch screen applications and potentially other flexible interface technologies.
Implementation Method 1
the mechanical contact of the liquid with the two electrodes establishing a variation in resistance or capacitance between the two electrodes
Implementation Method 2
the liquid being in contact with the two electrodes in such a way as to establish a short circuit between these two electrodes
Data Source
Figure 1A~1C
Figure 2~4
Figure 2A~4A
AI summary
The invention relates to a pressure sensor device including: a substrate made of an electrical insulating material including a first container, a second container, which is connected to the first container and two inner walls of which are each provided with an electrode, and a flexible diaphragm made of an electrical insulating material including an outgrowth and rigidly connected to the substrate in order to enable movement of the outgrowth between a position in which same is distant from a liquid filling the first container and at least one second position in which same exerts pressure on the liquid while thereby at least partially discharging same from the first container to the second container with mechanical contact between the two electrodes, said mechanical contact of the liquid with the two electrodes establishing a variation in resistance or capacitance between the two electrodes. The invention is useful in producing a touch-sensitive screen.