Mechanical properties of mammalian cells in suspension measured by electro-deformation

Abstract

We describe a planar, micro-fabricated device for generating fringing non-uniform electric fields. We used it to measure the mechanical properties of individual mammalian cells in suspension by deforming them in time-varying, non-uniform electric fields. Electrical stresses generated by the planar microelectrodes were used to trap and stretch cells, while cell deformation was observed using optical microscopy. Two distinct cell types were compared after fitting strain data with a three-parameter 'standard linear solid' model of visco-elasticity, and with a two-parameter power-law method. Chinese hamster ovary (CHO) cells were approximately twice as stiff as U937 human promonocytes, and CHO cells displayed an elastic behaviour with recovery of initial shape, while U937 strain data bore witness to plastic deformation. Our results demonstrate that electrical stresses generated by micro-fabricated electrodes permit mechanical characterization of distinct mammalian cell types.

A microfluidic device for simultaneous electrical and mechanical measurements on single cells

“…52,53 The main concern of the -EIS technique is that differences in impedance profiles between measurements taken with and without a cell's presence are usually small and sometimes unobservable. 51 In the meantime, several microfluidic-based devices have also been developed to measure the mechanical properties of single cells, such as micropipette aspiration, 54,55 electrodeformation, [56][57][58] and optical stretchers. 16,20,59,60 In micropipette aspiration, a cell is deformed by applying negative pressure through an aspiration channel.…”

Recent advances in microfluidic techniques for single-cell biophysical characterization

“…75,76 Electro-deformation devices utilize the DEP force for trapping and generating mechanical stimuli to quantify the deformability of individual cells. 77,78 The Young's modulus of tested cells can be extracted with either analytical models or numerical simulation. For improving the throughput of electro-deformation devices, a single-cell microchamber array device 79 was proposed.…”

“…On the other hand, the complex physical phenomena involved in electro-deformation and unknown cell electrical properties pose difficulties in extracting forces experienced by an electro-deformed cell. 75,77,78 Since the DEP force is determined by the dielectrical properties of cells, DEP-based techniques can also be used to electrically characterize cells, which is discussed in the electrorotation section under electrical characterization.…”

Trends in characterizing single cell's stiffness properties

“…Therefore, cell with higher diameter when exposed to higher voltage would be easily porated. On the contrary, MacQueen et al [70] fabricated an array of planar Ti/Pt electrodes for trapping and stimulating hamster ovary cell and human promonocyte cell. This work demonstrated the use of electrodeformation, which is defined as whenever a dielectric forces (DEP) was utilized to apply mechanical stimuli to deform a cell [71].…”