Biosensor Photodiodes Using Angle-Sensitive Filters to Distinguish Light
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Solution Overview
Problem
Existing CMOS image sensors face issues with spectrum shift due to angle-sensitive filters, leading to inaccurate light detection in applications like cell behavior observation and DNA sequencing, and current solutions complicate the fabrication process.
Innovation Solution
A biosensor design utilizing a substrate with first and second photodiodes, an angle-sensitive filter, and an immobilization layer, which exploits the spectrum shift property to distinguish different lights by obtaining and analyzing signal intensities from multiple filter configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an angle-sensitive filter is used for color isolation, then various color identification applications can be achieved, but the transmittance spectrum shifts when light irradiates at an angle greater than 0 degrees
Solution Approach 1:
The patent introduces a micro-lens array layer above the angle-sensitive filter to control and standardize the incident angle of light. By adding this optical element in the vertical dimension, the system maintains the spectral filtering capability of the angle-sensitive filter while compensating for angle-dependent spectrum shifts, thus resolving the contradiction between versatility and measurement precision.
2Measurement precision
If light angle directing components are added to reduce spectrum shift, then light detection accuracy improves, but the fabrication process becomes complicated and expensive
Solution Approach 1:
The patent segments the optical control function into individual micro-lens elements arranged in an array, where each micro-lens independently directs light to its corresponding pixel. This segmentation allows for standardized fabrication of simple micro-lens structures rather than requiring complex angle-directing components for the entire sensor, reducing overall device complexity while maintaining detection accuracy.
3Adaptability or versatility
If multiple photodiodes with angle-sensitive filters are used to distinguish different lights, then light distinction capability improves, but the device structure becomes more complex
Solution Approach 1:
The patent makes the angle-sensitive filter and micro-lens array configuration universal across all pixels in the sensor array. Each pixel uses the same filter and lens structure, allowing the system to distinguish different lights through spatial arrangement and signal processing rather than requiring structurally complex multi-filter configurations at each pixel, thus maintaining light distinction capability while reducing device complexity.
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
Effectively distinguishes between different lights by leveraging the spectrum shift phenomenon, providing accurate light detection without the need for complex fabrication processes.
Implementation Method 1
When light irradiates an angle-sensitive filter at an angle of more than 0 degrees, the transmittance spectrum of the filter wavelength will shift. This phenomenon is called a spectrum shift.
Implementation Method 2
a photodiode, and light emitted by the biological or biochemical sample may be directed to the photodiode
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A biosensor is provided. The biosensor includes a substrate, a first photodiode, a second photodiode, an angle-sensitive filter, and an immobilization layer. The first photodiode and the second photodiode are disposed in the substrate and define a first pixel and a second pixel, respectively. The first pixel and the second pixel receive a light. The angle-sensitive filter is disposed on the substrate. The immobilization layer is disposed on the angle-sensitive filter.