Flow Cytometer Photodetection Layout for Wider Dynamic Range
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Solution Overview
Problem
Semiconductor photodetection elements operating in Geiger mode have an insufficient dynamic range for applications like flow cytometers, which struggle with both dark and bright particles, and increasing the number of pixels to widen the dynamic range leads to increased chip area and cost.
Innovation Solution
A biological sample analyzer that includes a first semiconductor photodetection element for detecting light from a biological sample and a second element for detecting reflected light, with a processing circuit that acquires information from both signals, allowing for extended dynamic range without increasing chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to extend dynamic range, then the dynamic range is improved, but the chip area increases in proportion to the number of pixels
Solution Approach 1:
The patent implements a nested detection structure where a second photodetection element detects light reflected by a first photodetection element. This creates a hierarchical detection system where the second element captures only the reflected portion, allowing the first element to maintain high sensitivity for dark particles while the second element captures brighter reflected signals, thereby extending the overall dynamic range without increasing the chip area.
2Measurement precision
If the number of pixels is increased to extend dynamic range, then the dynamic range is improved, but the cost increases
Solution Approach 1:
The nested detection architecture allows the system to achieve extended dynamic range using a limited number of photodetection elements. By having the second element detect reflected light from the first element rather than requiring many parallel pixels, the system reduces the total number of pixels needed, thereby lowering manufacturing costs while maintaining wide dynamic range capability.
3Measurement precision
If the pixel size is maintained to preserve quantum efficiency, then the quantum efficiency is improved, but the chip area increases when the number of pixels is increased
Solution Approach 1:
The nested detection system allows each photodetection element to maintain its optimal pixel size for high quantum efficiency. The first element detects direct light with high quantum efficiency, while the second element detects reflected light from the first element. This hierarchical approach eliminates the need to increase pixel count, thereby maintaining quantum efficiency without increasing chip area.
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 configuration enhances sensitivity to a wide dynamic range, enabling accurate measurement of both dark and bright particles without saturating the photodetection elements, thus improving the analytical capabilities of the flow cytometer.
Implementation Method 1
a first semiconductor photodetection element that detects first light generated by irradiation of a biological sample and generates a first signal
Implementation Method 2
a second semiconductor photodetection element that detects second light reflected by the first semiconductor photodetection element among the first light and generates a second signal
Data Source
AI summary
A dynamic range is extended while suppressing an increase in a chip area.A biological sample analyzer of the present disclosure includes: a first semiconductor photodetection element that detects first light generated by irradiation of a biological sample and generates a first signal; a second semiconductor photodetection element that detects second light reflected by the first semiconductor photodetection element among the first light and generates a second signal; and a processing circuit that acquires information regarding the first light on the basis of the first signal and the first signal.