Extending upper cutoff frequency of electrochemical seismometer by using extremely thin Su8 insulating spacers

Here we presented a scheme based on MEMS technology to manufacture electrochemical seismometers and improved the seismometers´ high-frequency property. This device contained 2 pairs of perforated electrodes and 3 pieces of insulating spacers. Numerical simulations indicated the upper cutoff frequency f_c of the devices was related not just to the radium of holes in electrodes but to insulating spacers´ thickness. A thin layer of Su8 torn off from the substrate by a special craft was chosen to fabricate insulating spacer, and to ensure proper size of hole in electrodes and good consistency of electrodes, silicon wafers covered with platinum were applied to fabricate electrodes. Through this method we could obtain insulating spacers 300-5μm thick. Finally, we demonstrated, the upper cutoff frequency of the devices was expend to 50Hz by reducing the spacers´ thickness to 30μm, without any circuit compensation. Meanwhile, devices´ low frequency properties weren´t affected.