Graphene FET Sensor Array on CMOS Wafer for Liquid Detection
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Solution Overview
Problem
Conventional transistor-based sensors for chemical and biological analysis have limited sensitivity and scalability, often requiring external circuitry or chips for reading and processing outputs, which can be cumbersome and inefficient.
Innovation Solution
An integrated circuit (IC) chip with a read-out integrated circuit (ROIC) formed in a silicon-based CMOS wafer, incorporating a graphene field effect transistor (gFET) sensor array, where the gFETs have a 2D graphene channel and access transistors for direct liquid gate interaction, enabling enhanced sensitivity and scalability for chemical and biological analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional transistor-based sensors are used for chemical and biological analysis, then device complexity is reduced, but sensitivity and scalability are limited
Solution Approach 1:
The patent merges the sensor array and read-out circuitry onto a single integrated circuit chip. The gFET sensor array is fabricated directly on the CMOS substrate, with access transistors and read-out circuits integrated in the same device. This integration eliminates the need for external circuitry while maintaining high sensitivity through the graphene channel's superior charge carrier mobility and surface area-to-volume ratio.
Solution Approach 2:
The patent utilizes the two-dimensional nature of graphene as the channel material in gFETs. This 2D structure provides enhanced surface area for analyte interaction and improved charge carrier mobility compared to conventional 3D transistor channels. The liquid gate configuration further exploits the interface between the 2D graphene channel and liquid electrolyte to achieve high sensitivity for chemical and biological sensing.
2Productivity
If conventional transistor-based sensors are used, then ease of manufacture is improved, but scalability is limited
Solution Approach 1:
The patent divides the sensing function into multiple identical gFET elements arranged in an array on the CMOS substrate. Each gFET can be independently controlled by access transistors and read-out circuits, allowing parallel measurement of multiple analytes or multiple sensing locations. This segmented architecture enables scalable sensing applications while maintaining compatibility with standard CMOS fabrication processes.
3Productivity
If external circuitry is used for reading and processing sensor outputs, then device functionality is achieved, but operational efficiency is reduced
Solution Approach 1:
The patent combines the sensor array and read-out circuitry onto a single integrated circuit chip. The gFET sensor array is fabricated directly on the CMOS substrate, with access transistors and read-out circuits integrated in the same device. This integration eliminates the need for external circuitry while maintaining high sensitivity through the graphene channel's superior charge carrier mobility and surface area-to-volume ratio.
Solution Approach 2:
The integrated circuit chip is self-sufficient, with all necessary read-out and processing functions built-in. The access transistors automatically control signal routing from selected gFETs to the read-out circuits, and the CMOS processing circuits immediately process the sensor outputs without requiring external intervention. This self-service architecture improves operational efficiency by eliminating signal transmission delays and external processing requirements.
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 provides improved sensitivity and scalability for chemical and biological analysis by allowing direct liquid interaction with the graphene channel, enabling precise detection of analytes and biologic activity without the need for external circuitry, thus enhancing the accuracy and efficiency of sensor outputs.
Implementation Method 1
graphene field effect transistors (gFETs) serving as the sensing transistors and individually including: a graphene channel patterned in a two-dimensional (2D) layer of graphene
Implementation Method 2
a second insulating layer that acts as a passivation layer added above the gFET sources and the gFET drains of the sensor array, the second insulating layer patterned to form a passivation opening that allows direct contact of a sample liquid with the graphene channel, such that a liquid gate is formed above the graphene channel upon receipt of the sample liquid
Data Source
AI summary
An integrated circuit (IC) chip includes ROIC circuitry in a CMOS wafer with a top dielectric layer and at least one graphene field effect transistor (gFET) sensor array added above the CMOS wafer. The IC chip includes access transistors controlled by the ROIC circuitry and further includes sensing circuitry which includes the at least one gFET sensor array and a passivation opening that allows direct contact of a sample liquid with the graphene channels of the gFETs in the at least one gFET sensor array, such that a liquid gate is formed above the graphene channel upon receipt of the sample liquid. In some examples, the IC chip includes a process, memory controller, and memory. A system and a method have similar structures and perform the functions of the apparatus.