The possibility to use the electric field as a way to interact with the cell or tissue has recently led to many applications in research laboratories and industry: gene therapy, tumour treatment, electrochemiotherapy, cell fusion, cancer diagnosis and characterization of biological tissues. Among the AC electrokinetic techniques, the electrorotation allows identification of the dielectric properties of analysed bio-samples (single prokaryotic or eukaryotic cell, algae, or cell assemblies like spheroids) through the analysis of their rotational velocity when immersed within a rotating electric field. This paper presents a microfluidic device, dedicated to the determination of the electro-physiological properties of biological samples, which uses the combination of two forces, the negative dielectrophoresis force (nDEP) for the cell trapping and the electrorotation torque for the rotation of the biosample. An estimation of the biosample dielectric parameters is obtained through the analysis of the rotational velocity curve versus the electric field frequency. An observation set-up includes a fast camera that allows time controlled image sequence acquisition. Frames are then digitalized and from the analysis of the rotational velocity of the sample, its complex permittivity is determined, leading to the estimation of the conductivity and the permittivity of the membrane and the cytoplasm in the case of single cell.