Acoustic Standing Wave Generation for Particle Separation
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Solution Overview
Problem
Conventional acoustophoresis devices face limitations due to heat generation, use of planar standing waves, restricted fluid flow, and inability to capture diverse materials, along with challenges in controlling power supply to ultrasonic transducers for efficient performance.
Innovation Solution
The implementation of a multi-dimensional acoustic standing wave system within a flow chamber, utilizing a scaling circuit to provide an equivalent current source drive signal to an ultrasonic transducer, which includes a piezoelectric element, to create a three-dimensional acoustic field for effective separation of particles or fluids, allowing for continuous operation and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single planar acoustic standing wave is used for particle separation, then the structure is simple and easy to implement, but the particle trapping capability is limited and separation efficiency is reduced
Solution Approach 1:
The patent transitions from a single planar (2D) acoustic standing wave to a multi-dimensional (3D) acoustic standing wave field by superimposing multiple acoustic waves at different orientations. This creates a three-dimensional node structure that significantly enhances particle trapping capability across the entire flow chamber volume, resolving the contradiction between structural simplicity and separation efficiency.
Solution Approach 2:
The patent combines multiple acoustic waves propagating in different directions to create a superimposed multi-dimensional standing wave field. By merging these waves, the system achieves enhanced particle trapping throughout the 3D space while maintaining a unified acoustic field structure, balancing complexity and productivity.
2Use of energy by moving object
If conventional planar standing waves are used, then power consumption is lower, but heat generation occurs and continuous operation is hindered
Solution Approach 1:
The patent addresses heat generation from acoustic energy dissipation by designing a system where multiple acoustic waves are superimposed to create a multi-dimensional standing wave field. This distributes the acoustic energy more uniformly throughout the 3D space, reducing localized heating while maintaining effective particle separation, thereby enabling continuous operation.
3Ease of operation
If half or quarter wavelength acoustic chambers are used at micrometer scale, then laminar flow operation is achieved with minimal fluid dynamic optimization, but the system is not scalable and flow rates are extremely slow
Solution Approach 1:
The patent scales up from microscale half/quarter wavelength chambers to macroscale flow chambers by creating multi-dimensional acoustic standing waves. This approach maintains laminar flow conditions while enabling much higher fluid flow rates and system scalability, as the 3D acoustic field effectively spans the entire macroscopic chamber volume.
4Productivity
If acoustic standing waves are used to trap particles, then separation from primary fluid is achieved, but the standing wave must be turned off or removed which hinders continuous operation
Solution Approach 1:
The patent enables continuous particle separation by maintaining a stable multi-dimensional acoustic standing wave field throughout the flow chamber. The superimposed acoustic waves create a persistent 3D node structure that continuously traps and separates particles as they flow through the chamber, eliminating the need to turn the standing wave off and enabling uninterrupted operation.
5Productivity
If power is supplied to ultrasonic transducer to generate acoustic standing wave, then particle trapping is achieved, but control of power supply is challenging and efficient performance is difficult to implement
Solution Approach 1:
The patent employs a single ultrasonic transducer that generates multiple acoustic waves propagating in different directions. By controlling the phase and amplitude of the electrical signals supplied to the transducer, the system creates a multi-dimensional standing wave field, combining multiple functions in a single device and simplifying the power control architecture.
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 or fluids with enhanced trapping capabilities, continuous operation, and reduced energy usage, overcoming the limitations of conventional acoustophoresis devices by creating a robust three-dimensional acoustic field for effective particle trapping and separation.
Implementation Method 1
an ultrasonic transducer, having a transducer input impedance and located within the flow chamber includes at least one piezoelectric element driven by the equivalent current source drive signal to create an acoustic standing wave in the flow chamber
Implementation Method 2
Acoustic standing waves can exert forces on particles in a fluid when there is a differential in density and/or compressibility, otherwise known as the acoustic contrast factor. The pressure profile in a standing wave contains areas of local minimum pressure amplitudes at standing wave nodes and local maxima at standing wave anti-nodes.
Data Source
AI summary
Aspects of the disclosure are directed to an apparatus for separating a second fluid or a particulate from a host fluid. That apparatus comprises a flow chamber with at least one inlet and at least one outlet. A drive circuit configured to provide a drive signal to a filter circuit configured to receive the drive signal and provide a translated drive signal. An ultrasonic transducer is cooperatively arranged with the flow chamber, and transducer includes at least one piezoelectric element configured to be driven by the current drive signal to create an acoustic standing wave in the flow chamber. At least one reflector opposing the ultrasonic transducer to reflect acoustic energy.