Microsphere Preparation via Ultrasonic Stream Segmentation
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Solution Overview
Problem
Existing methods for producing microparticles, such as sonication and spray-based techniques, face challenges including high variability in particle size, limited scalability, and inability to produce particles larger than 100 microns, with sonication methods applying energy repeatedly and spray methods requiring high pressure and being difficult to scale.
Innovation Solution
A method using a sonication device with a tip that breaks a continuous stream of particle-forming solution into droplets with controlled size by varying sonication frequency and amplitude, allowing the droplets to solidify in a hardening solution, resulting in uniform particle size distribution from a few nanometers to several hundred micrometers and enabling easy scalability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bulk sonication is used to produce microparticles, then microparticles can be formed, but the particle size becomes highly variable and mostly smaller than one micron to about 20 microns
Solution Approach 1:
The continuous stream of particle-forming solution is segmented into discrete droplets by the sonication tip, which breaks the stream at regular intervals. This segmentation approach allows for controlled droplet formation with uniform size, overcoming the size variability problem of bulk sonication while enabling larger particle sizes through controlled droplet coalescence in the hardening solution.
Solution Approach 2:
The sonication tip operates periodically to break the continuous stream into droplets at regular intervals. This periodic action, driven by acoustic waves, ensures consistent droplet formation and size control, resolving the contradiction between particle size uniformity and size range limitations.
2Manufacturing precision
If nozzle spray method with acoustic wave is used, then single droplet formation with tight size control is achieved, but the production rate is limited and scalability is reduced
Solution Approach 1:
The system maintains a continuous stream of particle-forming solution that is continuously converted into droplets by the sonication tip. This continuous process, as opposed to discrete droplet formation, significantly increases production rate while maintaining tight size control through the periodic action of the sonication tip on the continuous stream.
3Force
If high pressure is applied to force polymer solution through nozzle, then solution can be pumped, but the pumping rate is limited and becomes difficult to sustain at high viscosity
Solution Approach 1:
The system replaces high-pressure mechanical pumping with acoustic energy from the sonication tip to propel and disperse the polymer solution. This substitution allows the solution to be processed without sustained high pressure, enabling higher pumping rates and better handling of viscous solutions through acoustic cavitation and vibration forces.
4Ease of manufacture
If spray drying or evaporation is used, then particles can be formed, but the particle size distribution becomes broad with high relative standard deviation
Solution Approach 1:
The invention introduces a hardening solution as an intermediary medium between droplet formation and final particle solidification. Droplets are formed in the hardening solution rather than through direct spray drying, allowing for more controlled solvent removal and polymer hardening. This intermediary step prevents the broad size distribution problem by maintaining droplet integrity during the phase change process.
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 produces microparticles with a tight size distribution and scalability, capable of producing large quantities efficiently, overcoming the limitations of previous techniques by applying sonication energy only once and using a continuous stream process.
Implementation Method 1
directing a particle forming solution comprising a particle forming liquid and a particle forming agent as a stream into contact with a sonicating tip of a sonication device under conditions sufficient to transform the stream containing the particle forming solution into a plurality of droplets
Implementation Method 2
The hardening solution contains ingredients such as surfactants or chemical reactants that cause the particles to harden either by loss of solvent or by a chemical reaction
Implementation Method 3
The hardening solution contains ingredients such as surfactants or chemical reactants that cause the particles to harden either by loss of solvent or by a chemical reaction resulting in formation of a new material
Data Source
AI summary
Methods of preparing particles using a sonication device are disclosed. The methods include directing a particle forming solution containing a particle forming liquid and a particle forming agent as a stream into contact with a sonicating tip of a sonication device under conditions sufficient to transform the stream containing the particle forming solution into a plurality of droplets having a substantially uniform size. The plurality of droplets are contacted with a hardening solution under conditions sufficient to solidify the droplets into particles having a substantially uniform particle size which are then recovered. Particles made in accordance with the methods can be solid or semi-solid and range in size from sub-micron to over 100 microns in diameter.