Cells Electrical Characterization: Dielectric Properties, Mixture, and Modeling Theories

Table 3

Techniques for nanomaterial characterization [71].

	Techniques	Problems
Electron microscopy methods	Scanning electron microscopy	(i) SEM requires conductive samples; (ii) Needs a high vacuum; (iii) Wet materials and biological samples
	Transmission electron microscopy	(i) Thickness bound is 200 nm; (ii) Time-consuming; (iii) A small field of view; (iv) The electron beam can damage biological portions; (v) For atomic-scale resolution, an ultrahigh vacuum is required; (vi) Light atoms exhibit contrast
Scanning probe microscopy methods	Scanning tunneling microscopy (STM)	(i) Conductive samples; (ii) Noise reduction is required
	Atomic force microscopy (AFM) or scanning force microscopy	(i) Small scan image size; (ii) Scanning speed is restricted; (iii) A slow rate of scanning leads to thermal drift; (iv) Images affected by hysteresis property of the piezoelectric material
Optic methods	Dynamic light scattering and fluorescence correlation spectroscopy	(i) Average particle size, error when larger atoms or impurity elements are present in a sample; (ii) In the nanoparticle sample, the analysis is biased toward highly refractile particles
	Absorption spectroscopy	(i) Error due to scattering via solid particles in heterogeneous samples; (ii) Restricted to turbid samples
X-ray methods	X-ray diffraction	Broad peaks from small crystals, making it problematic to verify the crystalline orientation
	X-ray photoelectron spectroscopy	(i) Errors in the chemical analysis for heterogeneous exteriors; (ii) Degradation during the study; (iii) A high vacuum is required