On-chip integrated optical stretching and electrorotation enabling single-cell biophysical analysis

Cells have different intrinsic markers such as mechanical and electrical properties, which may be used as specific characteristics. Here, we present a microfluidic chip configured with two opposing optical fibers and four 3D electrodes for multiphysical parameter measurement. The chip leverages optical fibers to capture and stretch a single cell and uses 3D electrodes to achieve rotation of the single cell. According to the stretching deformation and rotation spectrum, the mechanical and dielectric properties can be extracted. We provided proof of concept by testing five types of cells (HeLa, A549, HepaRG, MCF7 and MCF10A) and determined five biophysical parameters, namely, shear modulus, steady-state viscosity, and relaxation time from the stretching deformation and area-specific membrane capacitance and cytoplasm conductivity from the rotation spectra. We showed the potential of the chip in cancer research by observing subtle changes in the cellular properties of transforming growth factor beta 1 (TGF-β1)-induced epithelial–mesenchymal transition (EMT) A549 cells. The new chip provides a microfluidic platform capable of multiparameter characterization of single cells, which can play an important role in the field of single-cell research. A microfluidic chip utilizing optical fibers and electrodes can determine the mechanical and electrical parameters of different cell types. The biophysical behavior of cells are key markers for cellular identification, as well as for the study of diseased cells. Here, a team led by Wenhui Wang from Tsinghua University report a microfluidic chip that enables simultaneous probing of the mechanical and electrical behavior of single cells. Their device features two optical fibers to induce optical trapping and stretching of the cell, and four electrodes to measure electrical properties and for electrical rotation. They demonstrate the device for five different cell types, and study changes in the properties of cancerous cells.