Organic Transistor Floating Gate for Low-Voltage Cell Monitoring
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Solution Overview
Problem
Existing organic thin film transistors (OTFTs) are not suitable for monitoring electrophysiological signals from living cells due to the need for high operating voltages and low charge carrier mobility, which limits their frequency range and effectiveness as amplifying transducers.
Innovation Solution
A system comprising a plurality of organic thin film transistors with a floating gate electrode, source and drain electrodes, and an insulating layer, operating at low voltages (0.5 V to 2 V) and amplifying signals in the 1 Hz to 1000 Hz frequency range, without an external reference electrode, to measure and respond to electrophysiological signals from cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If organic thin film transistors are used for electrophysiological monitoring, then biological compatibility and mechanical flexibility are improved, but operating voltage requirement increases to tens of volts
Solution Approach 1:
The patent changes the operating voltage parameter from tens of volts to less than 3 volts by optimizing the organic semiconductor material properties and transistor structure. This allows the device to maintain biological compatibility while reducing energy consumption to levels safe for in-vivo applications.
Solution Approach 2:
The patent employs disposable organic transistor devices that can be fabricated at low cost on flexible substrates. These single-use devices eliminate the need for complex sterilization and long-term stability requirements, enabling safe low-voltage operation for temporary implantation or in-vitro applications.
2Adaptability or versatility
If organic thin film transistors are used for electrophysiological monitoring, then mechanical flexibility is improved, but charge carrier mobility decreases limiting frequency range
Solution Approach 1:
The patent uses composite material structures combining organic semiconductors with carefully selected dielectric and electrode materials. This composite approach optimizes charge carrier mobility within the organic semiconductor while maintaining the mechanical flexibility needed for biomedical applications.
Solution Approach 2:
The patent applies different material compositions and structures to different regions of the transistor device. The organic semiconductor channel is optimized for charge transport, while other regions prioritize mechanical flexibility and biocompatibility, achieving overall device performance that satisfies both requirements.
3Ease of manufacture
If conventional organic transistors are used, then fabrication on flexible substrates is simplified, but signal amplification capability is insufficient for cell activity detection
Solution Approach 1:
The patent designs the organic transistor with dynamic operating characteristics optimized for detecting small AC signals from cell activity superimposed on DC bias. The transistor operates in a specific region of its characteristic curve that maximizes transconductance and signal amplification while maintaining ease of fabrication.
Solution Approach 2:
The patent creates a universal organic transistor platform that simultaneously provides signal detection, amplification, and processing capabilities. The device can detect small electrophysiological signals, amplify them to usable levels, and output the processed signal, all while maintaining simple fabrication processes suitable for flexible substrates.
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 effectively monitors and maps electrophysiological signals from cells with high accuracy, enabling sensitive detection of rapid, low-amplitude extracellular signals and reducing the risk of undesired electrochemical processes, while avoiding the limitations of traditional OTFTs.
Implementation Method 1
an insulating layer fabricated between said source and drain electrodes, and said floating gate electrode
Implementation Method 2
a floating gate electrode... apt to be in contact with said cells to be monitored... detect dynamic, relatively small, charge variations
Data Source
AI summary
An organic transistor-based system for electrophysiological monitoring of cells is disclosed. The system includes a plurality of organic transistors each comprising: a floating gate electrode; a source electrode and a drain electrode; an organic semiconductor; an insulating layer; and a sensing area. A barrier mechanically separates said sensing area and a transistor area. Each organic transistor includes a control gate electrode coupled to a second portion of said floating gate electrode external to said sensing area by a capacitor. The control gate electrode is separated from said floating gate electrode by said insulating layer. The control gate electrode sets a working point of the organic transistor to which the control gate electrode belongs to by a control voltage (VGS) applied to it. In each organic transistor, an overlapping area defined by said control gate electrode formed above said floating gate is comprised between 9*10−4 cm2 and 2*10−3 cm2.