Integrated MOS-Bipolar Detector for Low Slope Factor Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional lab-on-a-chip devices have a high slope factor, making them inadequate for detecting small variations in electric potential, such as those required for DNA molecule detection, and existing advanced technologies like silicon nano-wires or carbon nanotubes are not suitable for industrialization.
Innovation Solution
An integrated electronic detector is designed using conventional FDSOI technology, comprising an MOS transistor and a bipolar transistor, where the bipolar transistor's base forms the input terminal, and the MOS transistor's drain serves as the output terminal, allowing for a low slope factor detection by transitioning between conducting and sub-threshold configurations in response to potential variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional field-effect transistors are used in lab-on-a-chip devices, then the device can be easily manufactured, but the slope factor is too high (60 mV/decade) for detecting small potential variations
Solution Approach 1:
The patent merges a bipolar transistor and an MOS transistor into a single integrated detector device. The bipolar transistor's base serves as the input terminal connected to the sensor, while the MOS transistor amplifies the signal. This combination allows the device to achieve low slope factor (high detection sensitivity) while remaining compatible with conventional FDSOI fabrication processes.
Solution Approach 2:
The patent utilizes the vertical structure of FDSOI technology by introducing a buried secondary control electrode (back gate) beneath the insulator layer. This adds a third dimension of control to the MOS transistor, enabling independent control of the channel through both the front gate and back gate, which is key to achieving the low slope factor.
2Measurement precision
If advanced technologies like silicon nano-wires or carbon nanotubes are used to reduce slope factor, then detection sensitivity improves, but fabrication becomes complex and不适合 industrialization
Solution Approach 1:
The patent changes the operational parameters of the MOS transistor by introducing a buried secondary control electrode that enables independent control of the channel. By controlling the potential of this back gate, the device achieves a slope factor of 11 mV/decade, significantly lower than conventional transistors, while using standard FDSOI fabrication processes.
3Power
If the MOS transistor operates in sub-threshold mode with floating gate, then large drain current variation is achieved, but the device configuration becomes more complex
Solution Approach 1:
The patent prepares the MOS transistor in advance by introducing a buried secondary control electrode and configuring it for sub-threshold operation. The back gate is pre-biased to enable the transistor to operate in the sub-threshold region, where small gate voltage changes produce large drain current variations. This preliminary configuration simplifies the operational complexity during actual sensing.
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 detector achieves a significantly lower slope factor of 11 mV/decade, enabling large variations in drain current for small potential changes, suitable for detecting molecules like DNA, while being fabricated using conventional methods compatible with industrialization.
Implementation Method 1
a bipolar transistor whose base forms the input terminal and whose collector is electrically connected to the gate of the MOS transistor
Implementation Method 2
the sub-threshold operation of an MOS transistor is an operation in which a current may be measured flowing between the source and the drain of the transistor while the gate-source voltage is below the threshold voltage
Implementation Method 3
For example, for a variation in potential VG of 0.3 volts on the gate of a conventional field-effect transistor, the value of the drain current Idrain of the transistor may be multiplied by 105
Data Source
AI summary
An integrated electronic detector operates to detecting a variation in potential on an input terminal. The detector includes a MOS transistor having a drain forming an output. Variation in drain current is representative of the variation in potential. A bipolar transistor has a base forming the input terminal and a collector electrically connected to the gate of the MOS transistor. The detector has a first configuration in which the bipolar transistor is conducting and the MOS transistor is turned off. The detector has a second configuration in which the bipolar transistor is turned off and the MOS transistor is in a sub-threshold operation. Transition of the detector from the first configuration to the second configuration occurs in response to the variation in potential.