A microfluidic platform for real-time enumeration and retrieval of low numberof cells

Şahin B., Karayalçın G., Toral T., Şen Doğan B., Özgür E., Zorlu Ö., ...More

Microfluidics 2022, Heidelberg, Germany, 11 July 2022, pp.80

  • Publication Type: Conference Paper / Summary Text
  • City: Heidelberg
  • Country: Germany
  • Page Numbers: pp.80
  • Middle East Technical University Affiliated: Yes


Precisely prepared standards for cell counting are essential to characterize the performance of any technology used to recover rare cells, like circulating tumor cells.  However, it is challenging to spike tumor cells at very low concentrations in a standard laboratory environment with conventional methods. In serial dilution, the variation becomes quite high.  Other platforms for single-cell picking are extremely high cost.  

We propose a low-cost, repeatable, and robust microfluidic platform to spike a very low number of cells (1-100) with high accuracy, without any sample loss and dead volume. The platform included a PDMS microfluidic chip and a flexible hydraulic reservoir (FHR)1 connected to the outlet reservoir, providing zero dead volume.  The microfluidic chip comprises two inlets – for the sample and the sheath flow – and one outlet for sample collection.  

Spike accuracy was tested with MCF-7 breast cancer cells. Fluorescently stained cells were passed through the channel at 5 µl/min flow rate and collected directly in the pipette tip connected to the FHR.  Cells passing through the microchannel were monitored under a microscope and counted in real-time by image processing.  Then, the collected cells were seeded to a well plate and counted for comparison.    The average collected cell count was 9.4±2.8, 51.5±5.1 and 98.7±4.3, for targeted 10, 50, and 100 MCF7 cells, respectively. The counting accuracy was demonstrated by linear regression between real-time versus collected cell counts with an R2 of 0.9908.  Average processing time for collecting 10 cells at the outlet was 5 minutes.  The microfluidic platform does not affect cell viability.

The proposed system provides a very low-cost and robust technique for accurate spiking of a low number of cells for analytical performance characterization of rare cell isolation platforms and any other analytical study requiring a few cells.  


1 Atay et al., 2021, Microfluidics and Nanofluidics, 25(1), 1–10.