Design And Fabrication Of Nanodevice For Cell Interfacing
Abstract
The goal of this thesis is to (a) design and fabricate a nanodevice that interface with cells and (b) optimize neuronal cell culturing protocol. The long term objective of this thesis is to perform intracellular electrical signal recording and stimulation of neuronal cells. To achieve this objective, a nanodevice with "Fin" shaped electrodes was designed that increases the electrode area and conductance so that it reduces the signal loss as shown in the case of traditional circular Nanopillar design. The overarching goal of neuroscience is to target and discover the relationships between the functional connectivity-map of neuronal circuits and their physiological or pathological functions. . For recording large number of neurons, technologies such as gold mushroom-shaped microelectrodes (Hai et al.), vertical nanowire electrode arrays (VNEAs) (Robinson et al.) and nanoFET technology (Tian et al.) are currently under development. The gold mushroom-shaped electrodes in order of microns are invasive for smaller cells with no successful recording for long durations. The VNEAs show high electrode impedance which causes large signal loss. The nanoFET shows higher noise levels and the manipulation of a single nanotube to penetrate a single cell is very challenging. This thesis presents the design and fabrication of a “Fin” shaped nanoelectrode which seeks to overcome the restrictions between electrode impedance and electrode size. Compared to the 3x3 array of 200nm diameter nanowire electrodes, the “Fin” electrodes reduces the interfacial impedance. The fabrication was done in Silicon on insulator wafer with conducting lines and contact pads completely insulated by Silicon dioxide layer and gold coated nanofins. Nanofins of width 200 nm were fabricated using Focused Ion Beam (FIB) milling. Both high density and low density nanofins were optimized and cells were cultured over them. The optimization of cell culture, adherence and differentiation protocols were done to grow cells over the nanofins.