Integrated Photodetector Alignment Using Pixel Current Feedback
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Solution Overview
Problem
Current instruments for massively-parallel biological or chemical sample analysis are limited by size, portability, operational requirements, and cost, making them unsuitable for point-of-care applications, and face challenges in aligning excitation light sources with integrated photodetectors, leading to nonuniform fluorescence measurements.
Innovation Solution
A method that determines the illumination position on an integrated photodetector based on current output measurements from its pixels, allowing for precise alignment of the excitation light source with the photodetector, using drain region current measurements to discriminate between excitation and fluorescent light, and adjust the alignment to ensure uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current instruments are used for massively-parallel sample analysis, then analysis capability is provided, but size and portability are limited making them unsuitable for point-of-care applications
Solution Approach 1:
The patent combines the excitation light source and integrated photodetector into a single integrated device structure, where the photodetector is directly coupled to the light source. This integration reduces the overall instrument size and eliminates the need for separate alignment systems, making the device suitable for point-of-care applications while maintaining massively-parallel analysis capability.
2Measurement precision
If excitation light source is aligned with integrated photodetector, then fluorescence measurement quality improves, but alignment precision is difficult to achieve
Solution Approach 1:
The system uses the photodetector's own pixel current measurements as feedback to automatically determine and adjust the illumination position. The photodetector measures the current output from its pixels, which corresponds to the amount of excitation light received, and this information is used to determine the optimal illumination position without requiring external alignment equipment or manual adjustment.
Solution Approach 2:
The patent implements a feedback mechanism where the photodetector continuously measures pixel current output in response to excitation light, and this measurement is used to adjust the illumination position on the photodetector. The system iteratively adjusts the illumination position based on the measured current until optimal alignment is achieved, ensuring uniform excitation across all pixels.
3Manufacturing precision
If pixel current measurements are used to determine illumination position, then alignment accuracy improves, but measurement and detection complexity increases
Solution Approach 1:
The photodetector serves multiple functions: it detects fluorescence signals from samples and simultaneously measures pixel current output to determine illumination position. The same photodetector array used for fluorescence detection is also used for alignment measurement, eliminating the need for separate alignment sensors or measurement systems.
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 enables accurate and uniform illumination of sample wells, improving the quality of fluorescence measurements and facilitating the use of these instruments in point-of-care settings by ensuring precise alignment of the excitation light source with the integrated photodetector.
Implementation Method 1
Integrated photodetectors have been developed that produce an electrical signal indicative of the intensity of incident light
Implementation Method 2
measuring an amount of current output from a drain region of a pixel of an integrated photodetector
Data Source
AI summary
Described herein are techniques for determining an illumination position on an integrated photodetector, as may be used within a fluorescence detection system. In some embodiments, such techniques may include determining an illumination position on an integrated photodetector based, at least in part, on a measurement of an amount of current output from a pixel of the integrated photodetector, the amount of current corresponding to an amount of excitation light (e.g., used for exciting fluorescence in a sample) that is received at the pixel. In some embodiments, such techniques may include measuring an amount of current output from one or more drain regions of one or more pixels of an integrated photodetector (e.g., regions used to draw away charge carriers corresponding to excitation light so as to not pollute collected charge carriers that correspond to fluorescence light to be detected).