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Real time monitoring of cellular activities like cell adhesion, spreading, proliferation, apoptosis and wound healing is of significant importance for understanding the mechanisms involved in cell–cell and cell–matrix communication, which eventually is expected to unfold some of the mysteries related to the functioning of diseased and normal cells. Towards this direction, surface topography plays a crucial role to provide a distinct in vitro environment for better manipulation and understanding of in vivo cell behavior. In this review, we focus on the real time monitoring of mammalian cell activities along with distributed electrical models using planar electric cell impedance sensing (ECIS) substrates and micro/nano patterned topographic cytosensors.

In this paper, a simple and convenient method based on impedance measurement has been proposed for the first time to evaluate the average porosity, pore radius, and internal surface area of macroporous silicon structure fabricated by electrochemical method. The porosity and the average pore radius have been obtained by developing a geometrical model and applying the generalized effective medium approximation theory to the dc and ac impedance measurement of both unoxidized and thermally oxidized macroporous silicon. The internal surface area per unit volume is then computed from the porosity and the pore radius using the same model. The method has been applied to a wide range of porosity from 30 to 58 fabricated on ptype <100> silicon with a resistivity of 10–20 Ω cm. Experimental verification of porosity, mean pore radius, and internal surface area have been performed by standard gravimetric technique and by topview and crosssection SEM imaging, respectively. A typical mean pore radius, porosity, and internal surface area of a macroporous silicon sample has been obtained to be 1.52 µm, 54.2, and 3565.7 cm2cm3, respectively, from the impedance measurement and 1.5 µm, 55, and 3666.7 cm2cm3from SEM and gravimetric analysis which shows that the results are within 2 of the values obtained by conventional methods. The advantages of this method over the other recently reported techniques for similar characterization have been discussed.

Reduced graphene oxide, in various configurations has been extensively researched as field effect transistor (FET) biosensor, but they usually exhibit low signal to noise ratio. In this paper, we report the fabrication of low noise FET biosensors with electrochemically reduced graphene oxide(ERGO) on fluorine doped tin oxide(FTO) glass, directly by electrochemical reduction of GO in solution. It has been observed that the sensor is capable of detecting down to1 fM concentration of Hep-B in serum with a dynamic range from 1 fM to 20 pM, linearity of around 95% and current sensitivity of 1.21 mA. Moreover, the signal to noise ratio is around 80 in serum, which is enhanced by more than one order of magnitude compared to the most sensitive reports. Further, the presence of Hep-B can be confirmed by the Lorentzian nature of noise spectra, which makes the detection more precise. The combined advantages of low cost and clean fabrication coupled with sensitive and reliable performance renders the device suitable for point of care diagnostics.