Nanofluidic FET Surface Charge Modulation
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Solution Overview
Problem
Existing nanofludic field effect transistors face challenges in completely turning off ionic current due to native surface charges on channel walls, requiring high gate voltages and lacking active electrical gate control.
Innovation Solution
A nanofludic field effect transistor with a membrane composed of three layers, including an electrically conductive gate layer between two insulating layers, allows for surface charge modulation by applying a gate voltage to control ionic current through a nanochannel filled with an ionic solution, enabling easy measurement and regulation of ionic flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniformly surface-charged ionic channel is used to modulate ionic current by gate voltage, then the ionic current can be modulated, but high gate voltages are required and it is very difficult to completely turn off the ionic current due to native surface charge on the channel walls
Solution Approach 1:
The patent changes the surface charge parameter of the nanochannel by applying a gate voltage that modulates the surface charge density. This allows dynamic control of the ionic current by altering the electrostatic conditions at the channel walls, enabling complete turn-off of ionic current while using lower gate voltages compared to uniformly charged channels.
2Reliability
If a bipolar ionic transistor is used to chemically modulate the surface charge of the nanochannel, then the ionic current can be completely turned off, but the transistor is passive with no active electrical gate control
Solution Approach 1:
The patent introduces an electrical gate as an intermediary component that mediates between the external control circuit and the nanochannel. This gate allows active electrical control of the surface charge modulation, combining the complete turn-off capability with active electrical control, thus bridging the gap between passive chemical modulation and active electrical control.
3Reliability
If high gate voltages are applied to modulate ionic current through a uniformly surface-charged channel, then ionic current modulation is achieved, but the device complexity and power consumption increase
Solution Approach 1:
The patent modifies the surface charge parameter dynamically through gate voltage control, allowing the nanochannel to transition between different conduction states. This parameter change approach enables efficient ionic current modulation with lower voltages, reducing the complexity of the gate control system while maintaining reliable modulation capability.
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 effectively turns on and off ionic current by applying a gate voltage, facilitating the measurement and control of ion transport, which can be used for chemical sensing and controlling biomolecules, offering a faster and more efficient alternative to traditional MOSFETs.
Implementation Method 1
by applying a gate voltage on the electrical gate, one can turn on the ionic current through the ionic channel, gating the transportation of ions through the ionic channel
Implementation Method 2
the ionic current through a uniformly surface-charged ionic channel can be modulated by the gate voltage applied on the channel
Data Source
AI summary
A field effect transistor device includes: a reservoir bifurcated by a membrane of three layers: two electrically insulating layers; and an electrically conductive gate between the two insulating layers. The gate has a surface charge polarity different from at least one of the insulating layers. A nanochannel runs through the membrane, connecting both parts of the reservoir. The device further includes: an ionic solution filling the reservoir and the nanochannel; a drain electrode; a source electrode; and voltages applied to the electrodes (a voltage between the source and drain electrodes and a voltage on the gate) for turning on an ionic current through the ionic channel wherein the voltage on the gate gates the transportation of ions through the ionic channel.