Design and development of a microfluidic platform with interdigitated electrodes for electrical impedance spectroscopy

In this paper, we describe the design, manufacturing, and characterization of a sensor array suitable for implementing wide broad band EIS for samples in aqueous solution on a microfluidic platform. Its wide-ranging capacity will allow the development of fluid characterization studies with results that are not possible to obtain in systems with a lower frequency range. The microfluidic system consists of four filling chambers and the fluid transport channels required for flushing and filling. At the bottom section of each chamber there is a gold-deposited electrode that allows electrical interaction with the sample. The chamber's geometry, transport channels, and the electrodes were designed using an optimization process through multiphysics simulations. Then, different manufacturing processes were developed experimentally for SU8 and PDMS which allowed to carry out the implementation of the microfluidic system. An electrical communication interface was designed for the interconnection of the microfluidic system with the vector network analyzer (VNA). Then, the measurements required to obtain the behavior of each sensor were developed. The results obtained show a predominant capacitive behavior of each sensor from low frequencies up to 2 GHz, allowing to obtain sufficient contrast between different aqueous solutions and a good repeatability in different sensing chambers with the same solutions.