a) Both glass substrate and extracellular fluid were modeled as infinite boundaries. The microelectrode height was set at 200 nm and its width to 30 μm as per our experimental needs. The neuron was positioned 50 nm above the microelectrodes to mimic the gap found at the neuron-electrode interfaces , and was modeled with diameters in the range of 5 to 80 μm, which is representative of most vertebrate and invertebrate cell diameters. Finally, the nano-edge was modeled at various heights from 0 (no nano-edge, similar to traditional planar electrodes) to 50 nm (same height as the cleft). ( 10, 16, 17 b) Table of physical values of electrical conductivity and relative permittivity used to run the computational simulation (Refs 18, 25, 26, 27 are listed in brackets in the table). ( c) Graphical representation of the sealing resistance disparity when computationally varying the nano-edge height and the cell’s diameter using a heat map, function of the cell’s diameter and the nano-edge height. Note the rapid increase in sealing resistance when the nano-edge is present and the cell’s diameter is equal or larger than the electrode (here 30 μm in diameter). ( d) Variation of the sealing resistance for each cell diameter when the nano-edge increases in height. When the cell’s diameter reaches a diameter equal to or larger than the microelectrode and that an edge is present, the sealing resistance reached a plateau of 7.49 ± 0.34 MΩ. ( e) Variation of the sealing resistance for each nano-edge height when the cell diameters increases. A dip between 10 and 25 μm can be attributed to current leakages happening when a cell’s diameter is smaller than the electrode. A similar plateau as for ( d) can be seen.