CytoSense

The portable/benchtop flow cytometer CytoSense combines high sensitivity with an extremely wide particle size range (from sub micron up to 1.5 millimeter diameter). What differentiates the CytoSense from conventional flow cytometers is its size range, its ability to gather flow cytometric data as well as pictures of particles, and the acquisition of multiple data points per particles. This results in a pulse shape of the particle, in which features and internal structure are clearly visible. It therefore allows for better (phyto)plankton species classification and analysis of filamentous algae (up to 4mm length).

There is a fixed flow cell mounted to measure both the small & thin cells and the big cells and colonies. Thanks to the usage of a carrier fluid, the particles align in one direction in the flow, and their speed through the laser beam is precisely known. Also fouling of the flow cell is prevented, which is crucial for autonomous use. The wide range of sample intake speed (0.07 - 17 ul/s) allows high particle loads (thousands of particles per second) as well as very low concentrations. The device is completely computer controlled and very compact (cylinder of 30 cm diameter) to fit in various enclosures.

Accessories & Upgrades

Although there is a standard CytoSense configuration, it is possible to extend the instrument with specific equipment to suit your needs. Due to the modular design upgrades and extra accesories are easily added.

Lasers and detectors

The CytoSense can hold up to 2 excitation lasers and 6 detectors, among which:

• Scatter sensors pointed at the flow cell at multiple angles.
• Deep red fluorescence: the main chlorophyll emission band.
• Orange fluorescence: allows distinction of species containing accessory pigments such as erythrins and phycobilins
• Yellow/Green fluorescence: typical for certain ciliates and cysts and sometimes lysing cells (such as after being ingested by zoo-plankton) - also useful for artificial fluorescent staining of cellular components, DNA etc.
• Blue fluorescence.
• Curvature detector: by distinguishing across the width of the flow cell the position of the particle in the flow cell can be known or, with longer particles, the way in which they are curved.
• Polarized light detector: some plankton species polarize light in a certain direction. We have developed a special sensor to measure this polarisation.

Furthermore, the CytoSense optical unit can be upgraded with a second laser to increase the available excitation/emission combinations for optimum species recognition and/or multiple color flow cytometry. In the case of 2-laser operation the following laser lines can be chosen from:
Laser 1: 460 nm or 488 nm or 532 or 561 nm.
Laser 2: 445 nm or 635 or 640 or 660 nm.

Imaging

By adding a camera to the instrument, particles can be photographed. A group of particles is targeted and photographed. This allows for easy identification of clusters. The images are coupled to the laser scans individually to allow further analysis.

Flow cell dimensions

To increase the size range of the CytoSense even further (up to 1.3mm diameter) the flow cell can be widened. This decreases accuracy in lower size ranges.