Dual Fingerprint Pressure Sensor With Transparent Flexible Electrodes
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Solution Overview
Problem
Current fingerprint and pressure sensors integrated with displays face challenges in achieving high transmittance and electrical conductivity, particularly due to limitations in materials like indium tin oxide, which affects their performance in flexible displays and high-frequency applications.
Innovation Solution
A dual sensor system is developed with first and second electrodes, channel regions, dielectric layers, and a capacitive change layer, utilizing materials like indium tin oxide, graphene, and nanostructures to enhance transmittance and conductivity, allowing for simultaneous fingerprint and pressure sensing with adjustable capacitance for pressure detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If indium tin oxide is used to form transparent electrodes in a matrix driving method, then transmittance is high and device structure is simple, but resistance value is high and noise is much, limiting high-frequency operation
Solution Approach 1:
The patent combines indium tin oxide (transparent conductive oxide) with metal nanoparticles or conductive polymers to create composite transparent electrodes. This composite structure maintains high transmittance while the metallic components provide lower resistance and reduced noise, enabling high-frequency operation up to 10 kHz or higher
2Illumination intensity
If indium tin oxide is used for transparent electrodes, then transmittance is high, but flexibility is low and high-frequency driving is difficult
Solution Approach 1:
The patent employs thin-film deposition techniques to create ultra-thin indium tin oxide layers combined with flexible substrate materials. The thin-film structure reduces brittleness and enables bending, while maintaining optical transmittance. This allows integration with flexible displays and wearable devices
3Measurement precision
If unit cells are used in fingerprint sensor, then noise is less and recognition is accurate, but process is complicated and transparency is decreased
Solution Approach 1:
The patent merges the fingerprint sensing function with the display structure by integrating capacitive sensing electrodes directly into the display's transparent electrode layers. This unified structure maintains high transparency while achieving accurate fingerprint recognition through capacitive coupling, eliminating the need for separate opaque sensor layers
4Area of stationary object
If physical buttons are removed from mobile devices, then screen size can be increased, but integrated sensor structure is required
Solution Approach 1:
The patent creates multi-functional integrated structures where the same electrode layers serve multiple purposes: display function, fingerprint sensing, and pressure sensing. This universal design allows physical button removal while maximizing screen area, as the sensing functions are embedded within the display structure itself rather than requiring separate components
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 system achieves high transmittance and electrical conductivity, enabling effective fingerprint recognition and pressure sensing with reduced noise and improved flexibility, suitable for use in flexible displays and wearable devices.
Implementation Method 1
a capacitive change layer formed by the first openings and the second openings and disposed between the channel region and the gate electrodes
Implementation Method 2
a thickness of the second dielectric layer may be changed by an external pressure so that a capacitance of the capacitive change layer is changed and thus the external pressure is sensed
Implementation Method 3
The second dielectric layer may include an elastic material, and a thickness of the second dielectric layer may be changed by an external pressure
Data Source
AI summary
A finger print and pressure dual sensor includes first electrodes disposed on a substrate and extending in a first direction, and source electrodes and drain electrodes disposed to face each other in the first direction; channel regions disposed on the substrate and electrically connected to the source electrode and drain electrode; a first dielectric layer disposed on the substrate, covering the first electrodes, the source electrodes, and the drain electrodes and having first openings for exposing the channel region; second electrodes disposed on the first dielectric layer and extending in a second direction; a second dielectric layer disposed on the first dielectric layer, covering the second electrodes and having second openings for exposing the channel region; gate electrodes disposed on the second dielectric layer, extending in the second direction and disposed on the channel region; and a cover layer disposed on the second dielectric layer and covering the gate electrodes.