Laser Speckle PSD Monitoring for Pharmaceutical Drying
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Solution Overview
Problem
Current methods for monitoring particle size distribution (PSD) during the drying process in pharmaceuticals are inadequate, as they lack real-time online monitoring capabilities to detect and prevent the formation of abnormally large agglomerates.
Innovation Solution
A method and device that utilize an at least partially coherent beam to illuminate particles, capturing scattered light with a pixelated photoelectric detector to create raw speckled images. These images are then processed to compute an ensemble-averaged intensity correlation, which is used by an inverse module to determine the PSD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard camera imaging is used to monitor particles, then the device is simple and easy to operate, but the spatial resolution is insufficient to extract accurate particle size distribution
Solution Approach 1:
The patent replaces conventional mechanical imaging systems with a laser speckle-based optical measurement system. Instead of using standard cameras to directly image particles, the system uses laser light scattering properties to encode particle size information, which is then decoded through computational algorithms. This substitution enables high-resolution particle size measurement without requiring complex mechanical imaging apparatus.
Solution Approach 2:
The patent changes the measurement parameter from direct spatial imaging to optical scattering intensity analysis. By measuring the intensity variations of scattered laser light (speckle pattern) rather than directly imaging particles, the system achieves high particle size resolution. The transformation from spatial domain to intensity domain allows for precise particle size extraction through correlation analysis of the speckle pattern.
2Measurement precision
If probe-based fiber bundle imaging is used, then measurement precision is improved, but the field of view becomes very small and may miss large agglomerates
Solution Approach 1:
The patent replaces the mechanical fiber bundle probe with a non-contact laser illumination system. Instead of using a physical probe that limits the field of view, the system uses laser light that can illuminate the entire powder bed surface. The scattered light is collected by a camera, allowing the system to monitor the entire area and detect large agglomerates while maintaining high measurement precision through speckle analysis.
3Ease of operation
If visual observation by trained personnel is used, then device complexity is minimized, but measurement precision is subjective and unreliable
Solution Approach 1:
The patent replaces subjective visual observation with an automated optical measurement system. The system uses laser speckle imaging and computational algorithms to objectively quantify particle size distribution. The automated image processing and correlation analysis provide consistent, repeatable measurements without relying on operator experience or judgment, thereby eliminating subjectivity while maintaining ease of operation through automated data collection and analysis.
4Measurement precision
If periodic sampling and particle size analysis are performed, then measurement precision is improved, but productivity is reduced due to invasive and slow measurement process
Solution Approach 1:
The patent replaces invasive physical sampling with non-contact optical measurement. Instead of extracting powder samples for analysis, the system uses laser light to measure particle size distribution in real-time through scattering patterns. This eliminates the need for physical contact with the powder, allowing continuous monitoring without interrupting the drying process or requiring periodic sampling, thereby significantly improving productivity while maintaining measurement precision.
Solution Approach 2:
The patent enables continuous real-time monitoring of particle size distribution throughout the drying process. The laser speckle imaging system operates continuously, providing ongoing data on particle size evolution. This continuous measurement capability allows for real-time detection of agglomeration and immediate process adjustment, eliminating the interruptions and delays associated with periodic sampling methods.
5Manufacturing precision
If delumping process is added to break hard aggregates, then manufacturing precision is improved, but loss of product increases and process time extends
Solution Approach 1:
The patent implements real-time feedback control based on laser speckle measurements. The system continuously monitors particle size distribution and detects the formation of hard aggregates as they occur. This feedback information is used to immediately adjust drying parameters such as temperature or agitation speed to prevent aggregate formation. By preventing the problem rather than addressing it after occurrence, the system avoids the need for additional delumping processes that would cause product loss and extend cycle time.
Solution Approach 2:
The system performs preliminary detection and prevention of aggregate formation through real-time monitoring. By detecting the early stages of agglomeration before hard aggregates form, the feedback control system can adjust process parameters to prevent the formation of problematic aggregates. This preliminary action eliminates the need for subsequent delumping operations, thereby reducing product loss and process time while maintaining manufacturing precision.
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 real-time, quantitative monitoring of PSD, allowing for early detection of agglomeration and enabling feedback control to prevent the formation of large agglomerates, thus improving process efficiency and product quality.
Implementation Method 1
illuminating a plurality of particles having a particle size distribution (PSD) by an at least partially coherent beam to produce scattered light
Implementation Method 2
capturing the scattered light by a pixelated photoelectric detector, thereby creating an ensemble of raw speckled images
Data Source
AI summary
A method of monitoring a particle size distribution (PSD) is provided. A plurality of particles having a particle size distribution (PSD) may be illuminated by an at least partially coherent beam to produce scattered light. The scattered light may be captured by a pixelated photoelectric detector, thereby creating an ensemble of raw speckled images. Based on the ensemble of the raw speckled images. an ensemble-averaged intensity correlation may be computed. The ensemble-averaged intensity correlation may be provided to an inverse module. The inverse module may be configured to determine the PSD based on the ensemble-averaged intensity correlation. The particle size distribution may be obtained from the inverse module.