The sensitivity of inter-digitated electrode (IDE) impedance sensors for adherent cell monitoring is investigated by computer simulation. Governing equation based on Maxwell’s equation is solved using finite element method by a commercially-available software to obtain impedance with/without living cells on sensor surface. For IDE, the current concentration is shown to be higher along the edges, as a result of which the electrode edges have a higher impact on impedance. The higher sensitivity is observed in case of higher cell density and larger cell size due to larger occupancy on sensor surface. It is also seen that the smaller electrode geometry displays higher sensitivity in the presence of adherent cell comparable or smaller than electrode spacing. This behavior is explained in view of the increase in number of electrode edges. It is also found out that the sensitivity of IDE outperforms to that of facing electrode (FE) for adherent cell sensing owing to the larger cell coverage and higher current concentration along the electrode edges. It is important to note that the IDE shows higher sensitivity than the FE in the presence of adherent cell, which is in contrast to the previously reported sensitivity behavior for floating cell. This makes IDE as a suitable choice of electrode for experimentalists working on adherent cell studies.

No abstract

The 3D computer simulation based on the finite element method was performed to obtain the impedance in the presence/absence of adherent living cells. The sensitivity of the inter-digitated electrode was investigated by varying the width (W) and spacing (S) for different number of electrode fingers N. It was found that the peak sensitivity corresponding to W/S < 1 and W/S > 1 exhibited higher sensitivity than W/S = 1. However, the sensitivity was relatively large when W/S < 1. Furthermore, the slope of the peak sensitivity curve decreased with the increase in N, emphasizing the fact that it has greater impact on sensitivity than W/S. It is important to note that the peak sensitivity due to smaller electrode width results in higher sensitivity. Hence, the experimentalists are recommended to choose the smaller electrode geometry with smaller electrode width in order to realize better sensitivity in the presence of adherent cell.