Ion Concentration Sensor with Extracted Transistors
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Solution Overview
Problem
Conventional ion concentration sensors, such as ISFETs, face challenges with low sensitivity and accuracy due to the large area requirement of transistors in fine cells, leading to variations in ion concentration detection.
Innovation Solution
An ion concentration sensor with a semiconductor substrate, a sensing section for accumulating electric charges, an electric charge transfer section, and an ion-sensitive film that changes with ion concentration, where the electric charges are injected only into the sensing section by applying a voltage to the semiconductor substrate, eliminating the need for additional charge injection electrodes and increasing the sensing section area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transistors are provided in each cell for ion concentration detection, then the sensing function is achieved, but the sensing section area is reduced and sensitivity decreases
Solution Approach 1:
The invention extracts and removes the transistors from each cell structure, eliminating the need for input transistors, output transistors, and reset transistors in every sensing cell. This extraction of unnecessary components frees up the sensing section area while maintaining detection functionality through alternative charge transfer mechanisms.
Solution Approach 2:
The invention implements a universal charge transfer mechanism where a single electric charge transfer section serves multiple sensing sections. Instead of each cell having its own dedicated transistors, the system uses a shared transfer pathway that can handle charges from multiple sensing areas, thereby increasing the effective sensing area without proportionally increasing device complexity.
2Ease of operation
If transistors are provided in each cell, then charge transfer is enabled, but device complexity increases and fine cell formation becomes difficult
Solution Approach 1:
The invention segments the device into distinct functional regions: multiple simple sensing sections that generate charges, a shared electric charge transfer section that moves charges, and an electric charge detecting section that reads charges. This segmentation allows each component to be optimized independently, with sensing sections being simple and small, while the transfer and detection sections handle the complexity.
Solution Approach 2:
The invention merges the charge transfer functionality from individual cell-level transistors into a unified electric charge transfer section that serves multiple sensing sections. This consolidation reduces the total number of active components and simplifies the overall device structure while maintaining the ability to transfer charges from all sensing areas.
3Measurement precision
If transistors are provided in each cell, then charge detection is possible, but variation in element characteristics reduces measurement accuracy
Solution Approach 1:
The invention changes the fundamental operating parameters from transistor-based voltage control to direct charge transfer and detection. By using electric fields and charge movement rather than transistor switching, the system avoids the parameter variations and threshold voltage differences that plague transistor-based sensors, achieving more consistent and reliable measurements across multiple cells.
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 enhances the sensitivity and accuracy of ion concentration detection by increasing the sensing section area and allowing for precise measurement of ion concentrations without additional electrodes, enabling high-resolution analysis of fine cells and efficient ion detection.
Implementation Method 1
a photodiode-type ion concentration sensor for detecting an ion concentration by detecting an amount of a change in electric potential level of a channel
Data Source
AI summary
An ion sensor is configured such that part of a P well on which part a sensing section is provided is different, in dopant concentration, from the other part of the P well so that electric charges are injected merely to the sensing section in a state where a voltage is applied to an N-type substrate.