Investigating Dielectric Impedance Spectroscopy As a Non-Destructive Quality Assessment Tool for 3D Cellular Constructs

In any three dimensional (3D) biofabrication process, assessing critical biological quality attributes of 3D constructs such as viable cell number, cell distribution and metabolic activity is critical to determine the suitability and success of the process. One major limitation in current state-of-the-art is the lack of appropriate methods to monitor these quality attributes in situ in a non-destructive, label-free manner. In this study, we investigate the feasibility of using dielectric impedance spectroscopy to address this gap. We first measured the relative permittivity of 3D alginate constructs with four different concentrations of encapsulated MG63 cells (1–6.5 million cells/mL) and found them to be statistically significantly different (p < 0.05). Within the tested range, the relationship between cell concentration and relative permittivity was noted to be linear (R² = 0.986). Furthermore, we characterized the β-dispersion parameters for MG63-encapsulated in alginate (6.5 million cells/mL). These results demonstrate that dielectric impedance spectroscopy can be used to monitor critical quality attributes of cell-encapsulated 3D constructs. Owing to the measurement efficiency and non-destructive mode of testing, this method has tremendous potential as an in-process quality control tool for 3D biofabrication processes and the long-term monitoring of cell-encapsulated 3D constructs.