Fabrication of Parylene-Based Flexible Microelectrode Arrays

In neural engineering,microelectrode arrays are the interfaces between nervous system and external electronic circuits.Their performance determines the effects of signal acquisition and stimulation of the whole nervous system.A Parylene-based hemispherical flexible microelectrode array was proposed.The microelectrode arrays were fabricated by photoresist melt technology and MEMS technology.The hemispherical morphology can ensure good contact between microelectrode and tissue,and will increase surface area to the double size compared with planar microelectrodes with the same bottom area which is helpful in decreasing interface impedance and power consumption.Experimental results showed that the interface impedance of the hemispherical microelectrodes decreased by 55% compared with planar microelectrodes whose bottom area is 1.3 times larger than that of the hemispherical microelectrodes,and the interface impedance varied with the contact area of microelectrodes and tissue caused by different dimensions of opening on the top of the microelectrodes.Comsol was used to simulate the current density of microelectrodes.Simulation results showed that the current density also varied with the opening dimension.Current density of microelectrode can be adjusted by adjusting the opening dimension at the top of microelectrode so as to meet the needs of different parts of tissue.