Flow Cytometer Optics and Pump Layout for Pulsation-Free Detection
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Solution Overview
Problem
Existing flow cytometers face challenges in providing reliable, compact, and efficient components for optical systems, fluidics, and peristaltic pumps, which are crucial for accurate cell analysis and sorting, while also dealing with pulsation issues and chromatic aberrations.
Innovation Solution
The flow cytometer incorporates a diode laser-based optical system with an elliptical beam profile, a composite microscope objective with minimal chromatic aberration, a pulseless peristaltic pump, and a wavelength division multiplexing system for precise light separation, along with a fluidic subsystem that reduces pulsation and a compact design for multiple excitation beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional peristaltic pump is used to supply liquid flow, then the pump structure is simple, but pulsation occurs in the liquid flow
Solution Approach 1:
The pump roller is divided into multiple independent compression sections (first compression section, second compression section, third compression section) along the tube path. Each section independently compresses the tube at different positions, allowing continuous liquid flow without pulsation while maintaining a relatively simple overall pump structure.
2Adaptability or versatility
If multiple excitation laser beams are used for flow cytometry, then detection capability is improved, but the optical system becomes more complex
Solution Approach 1:
Multiple excitation laser beams (first excitation laser beam, second excitation laser beam) are combined and directed through a shared optical path using beam combining optics. This allows multiple wavelengths to excite particles simultaneously while using a single detection optical system, improving detection capability without proportionally increasing system complexity.
Solution Approach 2:
The optical system is designed to handle multiple excitation wavelengths universally through a single detection path. The system can accommodate different laser sources (e.g., 488nm, 633nm) by adjusting optical elements while maintaining the same detection architecture, enabling versatile multi-parameter detection.
3Measurement precision
If a standard microscope objective is used, then chromatic aberration occurs, but the objective design becomes more complex to correct
Solution Approach 1:
The microscope objective employs asymmetric lens element arrangements and varying refractive indices across different glass elements to correct chromatic aberration. By strategically placing lenses with different dispersion properties in an asymmetric configuration, the objective achieves high optical resolution while managing the complexity through optimized rather than overly symmetric design.
4Area of stationary object
If an extended light source is used for illumination, then the field of view is improved, but beam collimation becomes more difficult
Solution Approach 1:
A beam combining optical element acts as an intermediary between the extended light source and the excitation beams. This element receives light from the extended source and transforms it into collimated excitation beams, enabling a large field of view while maintaining effective beam collimation through the intermediary optical component.
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 improved flow cytometer achieves high-resolution, reliable, and efficient cell analysis and sorting with reduced pulsation and chromatic aberrations, enabling better detection and sorting capabilities.
Implementation Method 1
a peristaltic pump for supplying a sample liquid that is free from pulsation and carries particles to be analyzed into the flow cell
Implementation Method 2
a laser diode (LD) based optical subsystem for illuminating particles passing through the flow cytometer's viewing zone
Implementation Method 3
a wavelength division multiplexer (WDM) for separating into multiple colored bands a beam of light
Data Source
AI summary
The disclosed flow cytometer includes a wavelength division multiplexer (WDM). The WDM includes an extended light source providing light that forms an object, a collimating optical element that captures light from the extended light source and projects a magnified image of the object as a first light beam, and a first focusing optical element configured to focus the first light beam to a size smaller than the object of the extended light source to a first semiconductor detector. The disclosed flow cytometer further includes a composite microscope objective to direct light emitted by a particle in a flow channel in a viewing zone of the composite microscope to the extended light source, a fluidic system and a peristaltic pump configured to supply liquid sheath and liquid sample to the flow channel, and a laser diode system to illuminate the particle in the flow channel.