Continuous-Flow Microfluidic Crystallization for Supersaturation Control
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Solution Overview
Problem
Existing screening techniques for crystalline polymorphs and morphology struggle with maintaining controlled, continuous-flow supersaturation conditions, leading to inconsistent polymorph formation and morphology due to decreasing supersaturation during crystallization.
Innovation Solution
A microfluidic system with a passive mixing zone and trap zone is used to maintain controlled supersaturation, allowing for continuous crystallization and retention of crystals for study, fabricated using additive technologies like 3D printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batch crystallization is used to screen polymorphs and morphology, then crystals can form under controlled conditions, but supersaturation decreases continuously during nucleation and growth leading to inconsistent polymorph formation
Solution Approach 1:
The patent implements a continuous-flow microfluidic system where supersaturated solution is continuously supplied to the trap zone, dynamically maintaining stable supersaturation levels during crystal formation. This replaces static batch conditions with dynamic continuous flow, ensuring consistent polymorph formation throughout the screening process
Solution Approach 2:
The system maintains continuous supply of supersaturated solution through the microfluidic device, with the trap zone continuously retaining crystals while fresh supersaturated solution flows through. This continuous action prevents supersaturation depletion that occurs in batch systems, ensuring reliable polymorph screening
2Productivity
If microtiter plates are used for high-throughput screening, then many conditions can be evaluated per run, but the technique requires automated systems and solid-state analysis which may not provide real-time monitoring
Solution Approach 1:
The patent transitions from traditional planar microtiter plate screening to a three-dimensional continuous-flow microfluidic system with trap zones. This dimensional change allows crystals to be retained in specific spatial regions while solution flows continuously, enabling both high throughput and real-time optical monitoring of crystal formation
Solution Approach 2:
The trap zone acts as an intermediary region within the microfluidic device that retains crystals while allowing continuous flow of supersaturated solution. This intermediary structure enables real-time monitoring of trapped crystals through transparent device walls while maintaining high-throughput continuous operation
3Productivity
If mini-batch crystallizers are used for parallel operation, then screening efficiency improves, but magnetic stirring causes crystal breakage
Solution Approach 1:
The patent replaces mechanical stirring with passive diffusion-based mixing in the microfluidic device. The trap zone retains crystals without mechanical agitation, eliminating crystal breakage while maintaining parallel screening capability through multiple microfluidic channels operating simultaneously
Solution Approach 2:
The invention extracts the mixing function from the crystal retention zone. Mixing occurs in separate inlet zones before solutions enter the trap zone, allowing crystals to be retained and monitored without exposure to mechanical stirring forces that would cause breakage
4Reliability
If 100 mL-1 L batch crystallizers are used for well-mixed conditions, then nucleation and growth kinetics can be studied, but the process is expensive and time-consuming
Solution Approach 1:
The patent segments the large-scale batch crystallization process into micro-scale continuous flow channels. Multiple parallel microchannels provide statistically significant kinetics data without requiring large volumes, reducing both time and material costs while maintaining measurement accuracy through continuous flow conditions
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 high-throughput screening of polymorphs and morphology under stable supersaturated conditions, overcoming issues of concentration gradients and supersaturation depletion, facilitating accurate monitoring and tracking of crystal growth.
Implementation Method 1
passive mixing zone
Implementation Method 2
fluid flowing through the microfluidic chamber
Implementation Method 3
the trap zone is positioned within the microfluidic chamber such that fluid flowing through the microfluidic chamber has a sufficiently low velocity to retain solute crystals formed in the trap zone within the trap zone
Implementation Method 4
screening of crystalline polymorphs and morphology under a controlled, continuous-flow, supersaturated environment
Implementation Method 5
continuous crystallization of solute, for example, by mixing with an antisolvent and/or cooling a saturated solution
Data Source
AI summary
The disclosure relates to a microfluidic system for the screening of polymorphs, morphology, and crystallization kinetics under well-mixed, continuous-flow at controlled supersaturations. The disclosure also relates to a method for screening crystalline polymorphs and morphology, and crystallization kinetics. The microfluidic system includes a microfluidic chamber having one or more inlets, a passive mixing zone, and a trap zone. The passive mixing zone promotes mixing of solvent, solute, and optionally antisolvent under stable, controlled levels of supersaturation. The trap zone similarly has stable, controlled levels of supersaturation and correspondingly low velocity to retain solute crystals formed in the trap zone for time-dependent evaluation.