Acoustophoretic Particle Separation via Ultrasonic Standing Waves
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Solution Overview
Problem
Current separation technologies face challenges in efficiently separating particles of varying sizes, particularly sub-micron particles, in fluid streams, often resulting in high operational costs, energy consumption, and inefficiencies in processes like oil recovery and biofuel production, as well as limitations in wastewater treatment and bioreactor processes.
Innovation Solution
The implementation of acoustophoretic separation technology using ultrasonic standing waves to create a three-dimensional acoustic radiation force that traps and concentrates particles, allowing for efficient separation of particles and droplets by overcoming fluid drag and buoyancy forces, with the use of piezoelectric transducers and advanced computer models to optimize particle trapping and collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional separation technologies are used to separate particles of varying sizes, then separation capability is achieved, but energy consumption and operational costs increase
Solution Approach 1:
The patent replaces conventional mechanical separation systems (centrifuges, filters, settlers) with an acoustic field-based separation system. Ultrasonic transducers generate standing waves that create acoustic radiation forces to manipulate and separate particles, substituting mechanical motion with acoustic field effects for energy-efficient separation across a wide particle size range
Solution Approach 2:
The patent utilizes changes in acoustic parameters (frequency, amplitude, standing wave patterns) to optimize particle separation. By adjusting the ultrasonic frequency and power levels, the system can selectively separate particles of different sizes, densities, and compressibilities, achieving high separation precision while maintaining low energy consumption
2Measurement precision
If conventional separation technologies are used for sub-micron particles, then separation is achieved, but efficiency decreases
Solution Approach 1:
The patent employs ultrasonic vibration at high frequencies (typically 20 kHz to several MHz) to generate standing waves in the fluid medium. This mechanical vibration creates acoustic radiation forces that are particularly effective for sub-micron particles, enabling efficient separation by exploiting differences in particle compressibility and density without the limitations of conventional mechanical methods
Solution Approach 2:
The system uses periodic ultrasonic waves to create stable standing wave patterns with fixed nodes and anti-nodes. Particles are periodically forced toward these stable positions, achieving efficient separation of sub-micron particles through repeated acoustic cycling rather than single-pass mechanical separation
3Quantity of substance
If acoustic radiation force is used to trap particles, then particle concentration increases, but device complexity increases
Solution Approach 1:
The patent employs ultrasonic transducers that serve multiple functions: generating standing waves for particle trapping, heating the fluid for enhanced separation, and potentially serving as reflectors or phase shifters. This multi-functionality reduces the need for additional dedicated components, thereby limiting device complexity while achieving high particle concentration
Solution Approach 2:
The system uses dynamically controllable transducer arrays where individual elements can be independently activated or phased to create movable or reconfigurable standing wave patterns. This dynamic control allows flexible particle manipulation and concentration at different locations without requiring complex fixed mechanical structures
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 enables efficient separation of particles across a wide size range, including sub-micron particles, with reduced energy consumption and operational costs, enhancing processes such as oil recovery, biofuel production, and bioreactor efficiency, while minimizing waste and environmental impact.
Implementation Method 1
At least one ultrasonic transducer is embedded in a wall of said flow chamber or located outside the flow chamber wall and is driven by an oscillating, periodic, modulated, or pulsed voltage signal of ultrasonic frequencies
Implementation Method 2
Standing waves are produced in acoustic resonators. Common examples of acoustic resonators include many musical wind instruments such as organ pipes, flutes, clarinets, and horns.
Implementation Method 3
Acoustophoresis is the separation of particles using high intensity sound waves. It has long been known that high intensity standing waves of sound can exert forces on particles.
Implementation Method 4
driven by an oscillating, periodic, modulated, or pulsed voltage signal of ultrasonic frequencies which drives the transducer in a higher order mode of vibration to create multi-dimensional standing waves in the flow channel
Data Source
AI summary
A system having improved trapping force for acoustophoresis is described where the trapping force is improved by manipulation of the frequency of the ultrasonic transducer. The transducer includes a ceramic crystal. The crystal may be directly exposed to fluid flow. The crystal may be air backed, resulting in a higher Q factor.