BJT Biosensor Sziklai Pair for CMOS-Compatible High-Gain Sensing
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Solution Overview
Problem
Existing biosensor technologies are not compatible with advanced CMOS technology nodes, limiting their sensitivity and integration capabilities for detecting biomolecules.
Innovation Solution
A biosensor device is developed, featuring an amplifying bipolar junction transistor (BJT) and a sensing BJT forming a Sziklai pair, with the sensing BJT integrated vertically on the amplifying BJT, creating a highly sensitive and tightly integrated biosensor structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing biosensor technologies are used, then detection capability is provided, but sensitivity and integration capabilities are limited
Solution Approach 1:
The patent combines the sensing BJT and amplifying BJT into a single integrated device structure, where the sensing element and signal amplification are merged into one biosensor device. This integration enables compatibility with advanced CMOS technology nodes while maintaining high detection sensitivity through the inherent current amplification capability of the BJT configuration.
2Measurement precision
If a sensing BJT with intrinsic gain is used, then detection sensitivity is improved, but device complexity increases due to the Sziklai pair configuration
Solution Approach 1:
The Sziklai pair configuration enables the sensing BJT to serve dual functions: it acts as both the sensing element that detects biomolecules and as an amplifying element that provides intrinsic current gain. This self-service approach allows the same transistor to perform multiple functions, reducing the need for separate sensing and amplification stages while achieving very high effective gain.
3Measurement precision
If the sensing BJT and amplifying BJT are tightly integrated, then sensitivity is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent employs a universal BJT fabrication process that can simultaneously create both the sensing BJT and amplifying BJT using the same manufacturing steps and materials. This multi-functional approach allows the integrated device to be manufactured using standard CMOS-compatible processes, reducing fabrication complexity despite the tight integration of multiple transistor functions.
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 biosensor achieves a very high effective gain due to the intrinsic gain of the sensing BJT, further amplified by the current gain of the amplifying BJT, enabling sensitive detection of biomolecules while being compatible with advanced CMOS technology nodes.
Implementation Method 1
an analyte has a gating effect on the base of the sensing BJT, changing the base current and therefore the collector and emitter currents of the sensing BJT
Implementation Method 2
the sensing BJT has an intrinsic gain associated with a BJT current gain which is further amplified by the current gain of the amplifying BJT, creating a very high effective gain
Data Source
AI summary
A biosensor device is provided. The biosensor includes an amplifying bipolar junction transistor (BJT) and a sensing BJT defining a sensing trench. The sensing BJT and the amplifying BJT are coupled to form a Sziklai pair with an emitter of the sensing BJT connected to a collector of the amplifying BJT and a collector of the sensing BJT connected to a base of the amplifying BJT.