Transparent Flexible Bioelectrode for Optical Tissue Sensing
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Solution Overview
Problem
Existing flexible biodevices are unable to perform optical observation or light irradiation on living tissue due to opaque electrodes, limiting their ability to study living tissue behavior.
Innovation Solution
A flexible device with a transparent insulating substrate and a carbon material extended gate electrode, combined with an organic semiconductor channel and an ionic liquid or gel gate dielectric, allowing for both electrical measurement and optical observation or light irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opaque electrodes are used in flexible biodevices, then electrical measurement capability is achieved, but optical observation and light irradiation on living tissue become impossible
Solution Approach 1:
The gate electrode material is changed from traditional opaque materials (such as gold) to transparent conducting oxide materials (such as ITO or IZO), fundamentally altering the optical parameter of the electrode from opaque to transparent while maintaining electrical conductivity. This enables light to pass through the electrode to reach the living tissue for optical observation and photogenetic manipulation while the electrode continues to perform electrical measurement functions.
Solution Approach 2:
The device employs a composite structure combining transparent conducting oxide materials for the gate electrode with organic semiconductor materials for the channel layer. This composite material approach allows the gate electrode to simultaneously achieve optical transparency and electrical conductivity, resolving the contradiction between electrical measurement capability and optical observation capability.
2Illumination intensity
If transparent materials are used for electrodes, then optical observation and light irradiation become possible, but electrical measurement accuracy may deteriorate
Solution Approach 1:
The thickness of the transparent conducting oxide gate electrode is optimized to balance optical transparency and electrical conductivity. By controlling the thickness parameter within a specific range, the electrode achieves sufficient light transmission while maintaining adequate electrical conductivity for accurate electrical signal measurement from the living tissue.
Solution Approach 2:
The gate electrode structure is designed with different functional regions: the gate electrode layer itself is optimized for transparency and conductivity, while the gate dielectric layer (ionic liquid or ionic gel) is optimized for electrical isolation and signal sensing. This local quality differentiation ensures that each layer performs its specific function optimally, maintaining electrical measurement accuracy while enabling optical transparency.
3Reliability
If gold thin film is used as extended gate electrode, then electrical conductivity is achieved, but biocompatibility and light transmissivity are compromised
Solution Approach 1:
The gate electrode material is changed from gold thin film to transparent conducting oxide materials (ITO, IZO), fundamentally altering the material parameters to achieve simultaneous transparency, conductivity, and biocompatibility. This material substitution resolves all three issues: light can pass through, electrical conductivity is maintained, and the material is biocompatible for direct contact with living tissue.
Solution Approach 2:
The device uses a composite material system where transparent conducting oxide provides the gate electrode function with transparency and conductivity, while ionic liquid or ionic gel provides the gate dielectric function with excellent biocompatibility. This composite approach ensures all requirements of transparency, conductivity, and biocompatibility are met.
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
Enables simultaneous electrical measurement of living tissue and optical observation or light irradiation, enhancing the capability to study living tissue behavior.
Implementation Method 1
the gate dielectric is an ionic liquid or an ionic gel
Implementation Method 2
a gate dielectric formed so as to cover all of the channel and a part of the extended gate electrode
Implementation Method 3
the extended gate electrode is a carbon material thin film having biocompatibility and light transmissivity
Implementation Method 4
the extended gate electrode may be a graphene film
Implementation Method 5
the channel is an organic semiconductor thin film
Data Source
AI summary
A flexible device (1) includes an insulating substrate (2), a source electrode (3), a drain electrode (4), and an extended gate electrode (5) formed on a surface of the insulating substrate (2) at intervals, a channel (6) arranged at an interval between the source electrode (3) and the drain electrode (4), and a gate dielectric (7) formed so as to cover all of the channel (6) and a part of the extended gate electrode (5), in which the insulating substrate (2) is a flexible thin film having light transmissivity, the extended gate electrode (5) is a carbon material thin film having biocompatibility and light transmissivity, the channel (6) is an organic semiconductor thin film, and the gate dielectric (7) is an ionic liquid or an ionic gel.