Dynamic Decimation for TOF Mass Spectrometry Data Compression
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Solution Overview
Problem
Time-of-flight (TOF) mass spectrometry instruments generate large amounts of data, requiring efficient data compression to reduce storage and processing times, especially as resolution increases, but existing methods are limited by hardware implementation and do not account for information content needed to discern peaks.
Innovation Solution
A method that dynamically adjusts the sampling rate based on the relationship between instrument resolution, digitization rate, and information content, allowing for data compression during acquisition or post-processing by preserving the minimum number of points required to reconstruct peaks, thereby reducing data without losing information content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high sampling rate is used to adequately sample analog pulses for lighter mass ions, then measurement precision is improved, but the quantity of data generated increases significantly
Solution Approach 1:
The patent applies dynamic decimation where the sampling rate is adjusted dynamically based on the time of arrival of ions. The decimator circuit changes its decimation factor during the mass scan, using higher sampling rates for lighter ions (earlier arrival times) and lower sampling rates for heavier ions (later arrival times), thus adapting the data acquisition rate to the actual information content needs at different time points
Solution Approach 2:
The patent changes the sampling rate parameter dynamically during data acquisition. The decimation factor is modified as a function of time of arrival, transitioning from lower decimation (higher effective sampling rate) at the beginning of the scan to higher decimation (lower effective sampling rate) toward the end of the scan, optimizing the balance between measurement precision and data volume
2Measurement precision
If the sampling rate is increased to improve resolution, then measurement precision is improved, but the time needed to transfer and process data increases
Solution Approach 1:
The decimator circuit dynamically adjusts the sampling rate during the mass scan based on resolution requirements. By reducing the sampling rate for heavier ions where high resolution is less critical, the system maintains necessary measurement precision while significantly reducing the total data volume that requires transfer and processing, thus decreasing the time loss associated with these operations
3Measurement precision
If a fixed high sampling rate is used throughout the mass scan, then measurement precision is maintained, but data compression efficiency is reduced
Solution Approach 1:
The patent implements a dynamic decimation strategy where the decimation factor varies during the mass scan. The decimator circuit transitions from lower decimation ratios for lighter ions to higher decimation ratios for heavier ions, maintaining measurement precision where needed while maximizing data compression efficiency for portions of the scan where high sampling rates are less critical
Solution Approach 2:
The sampling rate parameter is changed dynamically during the scan based on the time of arrival. The system adjusts the decimation factor as a function of mass-to-charge ratio and arrival time, optimizing the balance between maintaining measurement precision and achieving efficient data compression at different stages of the mass spectral acquisition
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 effectively compresses TOF mass spectrometry data by reducing the number of data points while maintaining peak integrity, leading to faster data transfer and analysis times, as demonstrated by plots showing increased compression efficiency with arrival time.
Implementation Method 1
In a time-of-flight (TOF) mass spectrometer or mass analyzer, ions of different masses are accelerated with the same amount of energy at a starting time and travel over the same fixed distance to a target detector. At the target detector, the different arrival times of the ions are recorded.
Data Source
AI summary
A time-of-flight (TOF) mass spectrometer analyzes a sample producing a time series of data points representing amounts of detected ions per unit time. A spectrometer resolution, a spectrometer digitization time period, and a minimum number points per peak needed to maintain the information content of a peak are received. A peak width value is calculated for each point from the resolution and a time of each point. The calculated peak width value for each point is divided by the minimum number points per peak. A maximum time difference between points for each point is produced. A point is selected based on the digitization time period. Adjacent points of the selected point are found. If a difference between the adjacent points does not exceed a sum of a maximum time differences of the adjacent points, the selected point is deleted to compress the time series.