Multichannel PMT Calibration for Flow Cytometer Signal Stability
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Solution Overview
Problem
Flow cytometers face challenges in calibration due to the sensitivity variations of photomultiplier tubes (PMTs) over time, making it difficult to compare results across different instruments and sessions, and requiring frequent re-calibration.
Innovation Solution
A method using a single multichannel PMT with a spectral sorting arrangement to separate fluorescence into multiple wavelength bands, where normalization factors are determined from fluorescent calibration samples to adjust measured intensities, allowing for accurate and long-term reliable calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separate PMTs are used for each wavelength channel, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple separate PMT detectors into a single multichannel PMT detector that can detect multiple wavelength bands simultaneously. This single detector module integrates the functionality of multiple individual PMTs, reducing device complexity while maintaining measurement precision through its ability to resolve multiple wavelength channels concurrently.
Solution Approach 2:
The single multichannel PMT detector is designed to perform multiple detection functions across different wavelength bands. Each channel of the multichannel PMT can detect specific wavelength ranges, making the single detector module universally capable of detecting various fluorescence signals that would otherwise require multiple separate detectors.
2Measurement precision
If frequent re-calibration is performed to account for PMT sensitivity variations, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
The patent implements preliminary calibration using fluorescent beads with known spectral characteristics before actual measurements. This preliminary calibration establishes baseline sensitivity factors for each wavelength channel, allowing the system to compensate for PMT sensitivity variations over time without requiring frequent re-calibration, thus maintaining measurement precision while improving productivity.
3Device complexity
If a single multichannel PMT is used, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent applies local quality by optimizing each wavelength channel within the multichannel PMT detector individually. Each channel is calibrated and characterized for its specific sensitivity characteristics, allowing the system to account for channel-to-channel variations. This per-channel optimization ensures that measurement precision is maintained across all wavelength bands despite using a single integrated detector.
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 method provides accurate and stable calibration, reducing the need for frequent re-calibration and enabling reliable comparison of results across different flow cytometers, while utilizing a single detector module to account for collective sensitivity fluctuations.
Implementation Method 1
a spectral sorting arrangement for separating fluorescence extending over a wavelength range into a plurality of at least four wavelength bands
Implementation Method 2
The detectors used are typically photomultiplier tubes (PMTs) and these are well known for having sensitivity that changes over time
Implementation Method 3
flowing a fluorescent calibration sample through the flow cell which fluoresces across the wavelength range
Data Source
AI summary
A calibration method for a flow cytometer with a multichannel detector module. During calibration, the fluorescence intensity data values for the different detector channels are used to calculate normalization factors needed to adjust subsequent data collected by each of the channels. By using a multichannel detector module, the results from the different flow cells can be reliably compared, so that multiple stages of flow cells can be arranged in series along a common flow path, for example to measure the same sample at defined time intervals.