Direct Electron Detector for Microcrystal Diffraction
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Solution Overview
Problem
Current methods for collecting electron diffraction patterns from microcrystals face challenges such as radiation damage, limited dynamic range of detectors, and integration accuracy due to spot overlaps, which degrade resolution and increase radiation damage.
Innovation Solution
Using a direct electron detector with a high sensitivity and fast readout rate, such as the Falcon III, to collect diffraction patterns with lower exposure and faster data acquisition, minimizing radiation damage and improving resolution by reducing exposure time and increasing data completeness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera with high dynamic range is used to accurately record both low and high pixel values, then measurement precision is improved, but device complexity increases and the camera may be more susceptible to radiation damage
Solution Approach 1:
The patent segments the diffraction pattern recording into multiple exposure frames with different exposure times. Low-resolution spots are captured in shorter exposures while high-resolution spots are captured in longer exposures, allowing each frame to be optimized for different signal intensities without requiring a single complex high dynamic range camera
Solution Approach 2:
The patent adds the time dimension by collecting diffraction data over multiple frames during crystal rotation. Instead of relying on a single complex camera setting, the solution spreads the measurement across multiple simpler frames that can be processed and combined to achieve the desired dynamic range
2Loss of information
If the nanocrystal is continuously rotated in the beam to create a sequence of frames, then data completeness is improved, but the dead time during detector readout introduces systematic gaps in sampling reciprocal space
Solution Approach 1:
The patent employs periodic action by rotating the crystal through multiple complete cycles and collecting frames at regular angular intervals. This periodic rotation ensures that all regions of reciprocal space are sampled repeatedly, filling in any gaps that occur during detector readout dead time and achieving complete data coverage
Solution Approach 2:
The patent maintains continuity of useful action by overlapping the rotation period with the detector readout time. The crystal continues rotating throughout the entire data collection process, ensuring that no region of reciprocal space is permanently missed during detector readout, thus maintaining continuous sampling
3Manufacturing precision
If longer camera lengths are used to compensate for lack of detector real estate, then spot overlaps are reduced and integration accuracy is improved, but the equipment complexity and data collection time increase
Solution Approach 1:
The patent employs dynamics by rotating the crystal during data collection rather than using a static long camera length. The rotation dynamically changes the orientation of diffraction spots relative to the detector, effectively spreading spots across different detector regions over time and avoiding overlaps without requiring extended camera length
Solution Approach 2:
The patent adds the rotational dimension to the data collection process. Instead of relying solely on the spatial dimension (camera length) to separate spots, the solution uses temporal and angular dimensions through crystal rotation, allowing spots to be separated in orientation space rather than requiring increased physical detector distance
4Object-affected harmful factors
If the exposure time is reduced to minimize radiation damage, then the microcrystal is protected from damage, but the signal-to-noise ratio decreases and measurement precision is affected
Solution Approach 1:
The patent segments the total exposure into multiple short-duration frames collected over an extended rotation period. Each individual frame receives minimal radiation dose, preserving the microcrystal, while the cumulative data from all frames achieves the necessary signal-to-noise ratio through aggregation
Solution Approach 2:
The patent maintains continuous useful action by rotating the crystal throughout the entire multi-frame data collection process. This continuous rotation ensures that diffraction data is continuously accumulated across all frames, compensating for the low signal in individual short-exposure frames and achieving high measurement precision without increasing per-frame radiation dose
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
Enables the collection of high-resolution electron diffraction data with reduced radiation damage and improved integration accuracy, allowing for faster and more precise structural model determination of microcrystals.
Implementation Method 1
recording at least one electron diffraction pattern (EDP) from the microcrystal having the first orientation or orientation group using a direct electron detector (DED)
Data Source
AI summary
Methods of collecting diffractionpatterns from a microcrystal having an ordered array of a molecule are disclosed, which nclude using an exposure rate of at most 0.02 electrons per square angstrom per second on the microcrystal and using a direct electron etector to record electron diffraction patterns. Also disclosed are methods of determining a structural model for a molecule, identifying a material present in a trace amount within a sample, identifying a polymorph, and identifying the stereochemistry of a molecule.