Acoustic Fluid Ejector Frequency Sweep to Prevent Cell Aggregation

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Solution Overview

Problem

Particle aggregation in acoustic wave-driven fluid ejectors, particularly those with closed cavities and solid nozzles, leads to inefficient ejection of biological cells due to acoustophoretic forces, causing clogging and reduced recovery in applications like mechanoporation.

Innovation Solution

Implementing frequency sweep excitation, increasing nozzle density, using acoustically transparent materials, and adjusting the ejector structure to enhance fluid flow drag forces to overcome acoustophoretic forces, thereby preventing particle aggregation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If acoustic radiation pressure is used to separate droplets or generate jets from a fluid reservoir, then ejection efficiency is improved, but particle aggregation occurs due to standing wave and acoustophoretic effects

Engineering Contradiction:

Improveejection efficiencyVSAvoidparticle aggregation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies dynamics by switching between different acoustic modes (e.g., from a mode with strong standing waves for ejection to a mode with traveling wave characteristics for particle suspension). This temporal variation in acoustic field characteristics prevents particle aggregation while maintaining ejection efficiency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements periodic action by alternately activating different acoustic modes in a cyclic manner. During ejection phases, one mode is activated, and during suspension phases, another mode is activated, creating a periodic cycle that prevents continuous particle aggregation

Inventive Principle:

Principle #19Periodic action

2Use of energy by moving object

If standing wave patterns are excited at modal frequencies, then energy efficiency is improved, but particle aggregation is caused by acoustophoretic forces

Engineering Contradiction:

Improveenergy efficiencyVSAvoidparticle aggregation

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The system dynamically switches between acoustic modes that favor energy efficiency and those that prevent particle aggregation. By temporally separating the benefits of standing waves (energy efficiency during ejection) from their harmful effects (particle aggregation), the system achieves both goals

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent converts the harmful acoustophoretic forces into a beneficial suspension mechanism by using specific acoustic modes to keep particles in motion and prevent aggregation, while other modes provide the energy-efficient ejection function

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Enhances the ejection efficiency of biological cells by minimizing aggregation, ensuring higher recovery rates and preventing device clogging.

Implementation Method 1

Some of these ejectors would utilize acoustic radiation pressure to separate droplets or generate jets from a surface of a fluid reservoir

Methodology Applied

Scientific EffectAcoustic radiation pressure: Acoustic Radiation Pressure

Implementation Method 2

acoustic waves can form standing wave patterns (pressure maxima and minima) in the fluid reservoir volume

Methodology Applied

Scientific EffectStanding wave:

Implementation Method 3

these particles can be collected and aggregated in pressure maxima and minima due to the acoustophoretic forces generated by the pressure field in the fluid reservoir

Methodology Applied

Scientific EffectAcoustophoresis:

Implementation Method 4

administering to a sample in need thereof a standing acoustic field comprising a frequency sweep excitation to eject particles during the sweep while not allowing a clear standing aggregation to develop

Methodology Applied

Scientific EffectFrequency sweep excitation:

Implementation Method 5

The flow drag will also move the fluid and the particles to the orifice during ejection

Methodology Applied

Scientific EffectFluid drag: Drag

Data Source

PatentUS20250360473A1Systems and methods for mitigating particle aggregation caused by standing wave and transient acoustophoretic effects

Publication Date: 2025.11.27 OPENCELL TECH

AI summary

In some embodiments according to the present disclosure, methods for mitigating particle retention are provided including the use of frequency sweep excitation to eject particle in the sweep. In some embodiments according to the present disclosure, the acoustically driven fluid ejector can be capable of being switched between multiple modes of operation. In other embodiments according to the present disclosure, the acoustically driven fluid ejector can be altered such that it includes the capability to be filled with a biocompatible material to aid in the mitigation of particle aggregation in the acoustically driven fluid ejector. In some embodiments according to the present disclosure, the solid structure and number of nozzles of the acoustically driven fluid ejector can be adjusted such that the ejector of the acoustically driven fluid ejector can be self-pumping, i.e. no external pumping mechanism other than acoustics driven flow drag is used.