Concave Photodiode Structure for Biosensor Light Collection
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Solution Overview
Problem
Current biosensors face challenges in efficiently collecting light emitted by fluorescence or chemiluminescence from biological samples, which limits their ability to accurately analyze and identify nucleic acid macromolecules.
Innovation Solution
The development of backside illumination CMOS image sensors with photodiodes featuring a concave surface on the light receiving surface, functionalized to contain nucleic acid macromolecules, and incorporating metal oxide layers to enhance light collection efficiency, along with a method for iteratively detecting and correlating light parameters from fluorescent or chemiluminescent labels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional planar microelectrode array structures are used, then device complexity is reduced, but light collection efficiency deteriorates due to light scattering and absorption by planar surfaces
Solution Approach 1:
The patent applies curvature by replacing conventional planar microelectrode surfaces with three-dimensional curved structures, specifically microwells arranged in an array. These microwells have curved side walls that guide light toward the electrodes, improving light collection efficiency while maintaining a manageable device structure through systematic arrangement of the curved elements.
2Measurement precision
If light guides are added to improve light collection, then light collection efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the light-guiding function with the microelectrode structure itself. The microwell structures serve dual purposes: they contain the electrodes and simultaneously act as light guides through their curved geometry. This integration eliminates the need for separate light guide components, reducing manufacturing complexity while maintaining improved light collection efficiency.
3Measurement precision
If conventional planar surfaces are used, then manufacturing is simpler, but light scattering and absorption increase reducing measurement precision
Solution Approach 1:
The patent replaces planar surfaces with curved microwell surfaces that actively guide light through total internal reflection. The curved geometry of the microwell side walls directs scattered light toward the electrodes, converting what would be lossful scattering into useful signal collection, thereby improving detection sensitivity without excessive structural 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
This approach significantly improves light collection efficiency, enabling precise analysis and identification of nucleic acid macromolecules by effectively capturing and measuring the emitted light, thereby enhancing the accuracy of biological or chemical analysis.
Implementation Method 1
the curved side walls of which are configured to guide light toward the electrode
Data Source
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AI summary
A photodiode(112,200,400,500) includes a semiconductor substrate(210) having a first surface(211) and a second surface(212,412,512), and a light sensing junction(220) located adjacent to the first surface(211). The second surface(212,412, 512) is located opposite the first surface(211), and the second surface(212,412,512) includes a concave surface covering a recessed region(415,515) in the semiconductor substrate(210).