Dynamic mechanical measurement of the viscoelasticity of single adherent cells

Abstract

Many recent studies on the viscoelasticity of individual cells link mechanics with cellular function and health. Here, we introduce a measurement of the viscoelastic properties of individual human colon cancer cells (HT-29) using silicon pedestal microelectromechanical systems (MEMS) resonant sensors. We demonstrate that the viscoelastic properties of single adherent cells can be extracted by measuring a difference in vibrational amplitude of our resonant sensor platform. The magnitude of vibration of the pedestal sensor is measured using a laser Doppler vibrometer (LDV). A change in amplitude of the sensor, compared with the driving amplitude (amplitude ratio), is influenced by the mechanical properties of the adhered cells. The amplitude ratio of the fixed cells was greater than the live cells, with a p-value <0.0001. By combining the amplitude shift with the resonant frequency shift measure, we determined the elastic modulus and viscosity values of 100 Pa and 0.0031 Pa s, respectively. Our method using the change in amplitude of resonant MEMS devices can enable the determination of a refined solution space and could improve measuring the stiffness of cells. V

Simultaneous Measurement of Multiple Mechanical Properties of Single Cells Using AFM by Indentation and Vibration

“…According to the simulation results, 1) the amplitude ratio β increases with increasing actuation frequency ω below the resonance frequency and decreases above the resonance frequency ω 0 [see Fig. 2(a) and (c)], this is consistent with other report [12]. And, 2) the phase difference θ increases with increasing actuation frequency below the resonance frequency and approaches a constant value above the resonance frequency [see Fig.…”

“…According to the thickness-corrected Hertz model [33], the Young's modulus of the sample cell was calculated based on the indentation curves obtained in the AFM indentation experiment, as previously described in detail [28], [36]. Then, the cellular elasticity parameter k was calculated from the indentation curves according to (10)- (12).…”

“…Therefore, the cellular mechanical properties can be used as label-free biomarkers to reflect the physiological properties of cells [11], tissues and organs. Therefore, understanding cellular mechanical properties could be a useful strategy for the early diagnosis of serious diseases and to provide personalized medication [10], [12]- [14].…”

“…Furthermore, an array of micro-electro-mechanical system (MEMS) resonant sensors combined with a laser Doppler vibrometer (LDV) can be utilized to measure the micromechanical properties of bio-samples and hydrogels, including their mass and viscoelasticity parameters, based on various vibration quantities, such as resonance frequency shifts, vibrationinduced phase shifts and amplitude ratios [8], [12], [21]- [24]. However, using QCM, QCM-D and resonant sensors requires that the biological samples be adhered onto measuring platforms that must be sterilized and functionalized with collagen for biocompatibility.…”

Characterization of the mechanical properties of resected porcine organ tissue using optical fiber photoelastic polarimetry

“…However, there remain issues with resolution and understanding tissues with micron-scale heterogeneity. Parallel efforts have emphasized single cell methods, leaving tissue-level analysis out of reach [7][8][9].…”