Acoustic Focusing Chip with Reflective Portions for Cell Alignment
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Solution Overview
Problem
Conventional flow cytometers face challenges in accurately aligning cells due to irregular flow paths, and acoustic focusing alone lacks sufficient performance for practical use, often requiring a sheath liquid that dilutes cell samples and can impair cell growth. Additionally, existing technologies struggle with maintaining strength and preventing thermal deformation under ultrasonic wave application.
Innovation Solution
An acoustic focusing chip with a simple structure that incorporates ultrasonic waves, reflective portions, and a heat conductive design to enhance focusing accuracy and durability, eliminating the need for a sheath liquid by forming ultrasonic standing waves within the chip's flow path, thereby maintaining cell sample concentration and preventing thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acoustic focusing is used to align cells, then measurement precision is improved, but device complexity increases and heat generation occurs
Solution Approach 1:
The chip is divided into distinct functional regions: an ultrasonic wave application region with reflective portions for acoustic focusing, and an imaging region for measurement. This segmentation allows the complex acoustic focusing function to be isolated in a specific zone while keeping other areas simple for their intended purposes.
Solution Approach 2:
Reflective portions are introduced as intermediary structures within the flow path to redirect ultrasonic waves. These reflective surfaces act as mediators that enhance acoustic focusing by reflecting waves toward the center of the flow path, improving cell alignment without requiring complex external acoustic equipment.
2Measurement precision
If ultrasonic waves are applied for flow focusing, then cell alignment is improved, but temperature rise occurs causing harmful effects
Solution Approach 1:
The imaging region is extracted and separated from the ultrasonic wave application region. This allows optical measurement to be performed in a zone free from ultrasonic heating, while acoustic focusing occurs in a dedicated region where heat can be managed separately.
Solution Approach 2:
The flow path itself acts as an intermediary medium that transports cells from the ultrasonic focusing region to the imaging region. This allows cells to be aligned acoustically and then measured optically without direct exposure to both ultrasonic waves and measurement equipment simultaneously, reducing cumulative thermal effects.
3Measurement precision
If sheath liquid is added for hydrodynamic focusing, then cell alignment is improved, but cell concentration is diluted and cell growth is impaired
Solution Approach 1:
The patent replaces the mechanical hydrodynamic focusing system (which requires sheath liquid flow) with an acoustic focusing system using ultrasonic waves. This substitution eliminates the need for sheath liquid while achieving comparable or superior cell alignment through acoustic radiation pressure and standing wave formation.
Solution Approach 2:
The focusing mechanism is changed from hydrodynamic (fluid flow-based) to acoustic (wave-based). By changing the physical parameter from fluid velocity profiles to ultrasonic wave frequency and amplitude, the system achieves focusing without adding external fluids, thereby maintaining cell sample concentration.
4Measurement precision
If reflective portions are added to enhance ultrasonic wave reflection, then acoustic focusing is improved, but chip strength near flow path decreases
Solution Approach 1:
The flow path wall thickness is optimized locally: thinner walls are provided in regions where reflective portions are located to enhance acoustic reflection, while thicker walls are maintained in regions requiring structural strength. This local differentiation of wall thickness allows simultaneous optimization of acoustic performance and mechanical strength.
Solution Approach 2:
The chip is constructed using composite material layers with different properties: outer layers made of glass or sapphire glass for strength and optical clarity, and an inner layer made of silicon for acoustic reflection. This composite structure provides both the required mechanical strength and acoustic focusing performance.
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
The solution achieves high-accuracy cell alignment without dilution, improves ultrasonic wave generation efficiency, increases measurement throughput, and enhances heat dissipation and rigidity, while maintaining chip strength and preventing thermal issues.
Implementation Method 1
an acoustic element arranged on the plate surface in the ultrasonic wave application region
Implementation Method 2
a reflective portion capable of reflecting the ultrasonic waves toward the flow path is formed along the flow path in the ultrasonic wave application region
Implementation Method 3
forming ultrasonic standing waves within the chip's flow path
Implementation Method 4
a heat conductive portion is provided on an opposite side of the flow path with respect to the reflective surfaces
Data Source
AI summary
An acoustic focusing chip is irradiated with ultrasonic waves from an acoustic element P. A flow path having an inlet and an outlet is formed inside of a plate body along a plate surface. A region proximate to the inlet of the flow path of the plate body is set as an ultrasonic wave application region for receiving irradiation of the ultrasonic waves. The acoustic element is arranged on the plate surface in the ultrasonic wave application region. A reflective portion capable of reflecting the ultrasonic waves toward the flow path is formed along the flow path in the ultrasonic wave application region. Thereby, the flow focusing ability, heat dissipation, and strength retention can be cost-effectively improved with a simple configuration.