FET Ionic Sensor with Segmented Reference Electrodes
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Solution Overview
Problem
Conventional field effect transistors (FETs) for detecting ionic materials face challenges in miniaturization and have high scattering during manufacturing, leading to variations in measured electrical values, which complicates the detection of similar samples and requires the use of multiple FETs for accurate results.
Innovation Solution
The design includes a field effect transistor with a semiconductor substrate, oppositely doped source and drain regions, an insulating layer, and strategically placed reference electrodes to improve signal-to-noise ratio and reduce scattering, allowing for accurate detection of ionic materials using fewer devices. The configuration includes a separation layer and specific materials for the electrodes, such as silicon dioxide or metal oxides, and reference electrodes made from polysilicon or platinum, enabling miniaturization and enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional FET design with a single large reference electrode is used, then the reference electrode can provide stable voltage, but the overall sensor size cannot be reduced
Solution Approach 1:
The reference electrode is divided into two separate electrodes (first reference electrode and second reference electrode) instead of using a single large electrode. This segmentation allows the reference electrode functionality to be distributed across smaller components, enabling sensor miniaturization while maintaining stable voltage reference through the combined action of both electrodes
Solution Approach 2:
The reference electrodes are positioned in different spatial dimensions relative to the insulating layer - one at the edge and one spaced apart - creating a three-dimensional configuration that provides stable voltage reference while reducing the planar footprint of the sensor
2Manufacturing precision
If conventional FET manufacturing processes are used, then standard fabrication can be maintained, but scattering between devices is high leading to wide variation in measured electrical values
Solution Approach 1:
The insulating layer is positioned to contact specific portions of the source and drain regions rather than the entire structure, creating localized electrical characteristics that reduce device-to-device variation. This local modification of the insulating layer configuration improves manufacturing precision by controlling where electrical interactions occur
Solution Approach 2:
The configuration parameters of the reference electrodes (positioning one at the edge and one spaced apart from the insulating layer) are optimized to reduce scattering effects. By changing the spatial parameters of the reference electrode system, device uniformity is improved while maintaining compatibility with standard fabrication processes
3Measurement precision
If multiple FET devices are used to filter and average values, then measurement accuracy can be improved, but device complexity and cost increase
Solution Approach 1:
The reference electrode system is extracted and configured as two separate electrodes with specific spatial relationships to the insulating layer. This extraction and reconfiguration reduces scattering effects that normally require multiple devices for averaging, thereby improving measurement precision while reducing the number of FET devices needed
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
This configuration enables accurate and efficient detection of ionic materials, such as biomolecules, with improved signal-to-noise ratio and reduced scattering, allowing for precise measurement using one or a small number of FET devices, facilitating the miniaturization of the detection system.
Implementation Method 1
a biosensor capable of identifying an antigen-antibody reaction by detecting a current that varies due to a change in the surface charge concentration of a semiconductor inversion layer
Implementation Method 2
an insulating layer disposed on the channel region and formed of an electrically insulating material
Data Source
AI summary
A field effect transistor for detecting ionic material and a method of detecting ionic material using the field effect transistor. The field effect transistor for detecting ionic material includes a substrate formed of a semiconductor material, a source region and a drain region spaced apart from each other in the substrate and doped with an opposite conductivity type to that of the substrate, a channel region interposed between the source region and the drain region, an insulating layer disposed on the channel region and formed of an electrically insulating material, a first reference electrode disposed at an edge of the upper portion of the insulating layer and a second reference electrode disposed to be spaced apart from the insulating layer.