Axis 1 – Self-Adaptive Architectures:

Real-time tracking of a single cell in a lab-on-a-chip

There is huge interest in biology for microdevices that can analyse very small biological samples by combining microfluidic technology with electrical and/or mechanical functions (lab-on-a-chip). This can even be downsized at the single-cell level, like in a cell sorter at the output of which single cell analysis is to be performed in parallel in several tens of different bioreactors. However, one of the main challenges is to handle about 100 cells per second. This requires being able to monitor and control in real time the high-speed displacements of the cells during their journey in the chip. Performing such task with classical vision-based sensors is tremendously harsh, due to the high number of cells that must be handled at the same time.

A real-time position sensor, directly integrated within this kind of device, has been developed by EIPHI in collaboration with EPFL Lausanne (International Collegium SMYLE between FEMTO-ST and EPFL) and Ecole Centrale at Lyon, and published in Lab-On-A-Chip. It is based on impedance measurement, whose magnitude varies when the position of a cell trapped between purposely-designed electrodes evolves. Helped by a further signal processing, fast sampling, sensitive and repeatable real-time measurement of the cell position is performed, as conceptually proved with 8.7-µm-diameter polystyrene beads.

Illustration (left) and photograph (right) of the chip. The fluidic actuation guides the beads into the channel, and focusing electrodes center them in the channel section. The position of the beads is detected by impedance measurement in the detection area.

B. Brazey et al., “Impedance-based real-time position sensor for lab-on-a-chip devices”, Lab-On-A-Chip 18, 5, 818-831 (Mar. 7 2018). DOI: 10.1039/c7lc01344b