Silicon compatible process to integrate impedance cytometry with mechanical characterization

We introduced 3D silicon electrodes to perform impedance cytometry on single cells without compromising practical integration with sensors measuring complementary properties, e.g., mechanical properties. Microfabricated from a highly-doped SOI wafer, some design modifications were made to improve their sensing performance. According to simulations, a trajectory-free measurement can be obtained by replacing the silicon backside under the sensing area with an insulating material. In addition, enlarging the distance between the electrodes and the surrounding silicon structure and filling them with some insulating material results experimentally in better signal quality and reduced parasitics. Combining these two device modifications improves the system frequency response and the signal quality at higher frequencies. The proposed process aims at creating silicon-based electrodes for impedance spectroscopy applications while providing opportunities to integrate them with MEMS sensors and actuators.