Design of an impeller-mounted electrode array for EIT imaging

The information content in electrical impedance tomography (EIT) reconstructions is limited by the number of independent impedance measurements acquired for each image frame. This paper describes the design and construction of an electrode array mounted onto a rotating impeller used for mixing processes. By combining the process compliant rotation of the electrodes with a dynamic measurement protocol, a substantial increase in the number of independent measurements is reported. A pitch-blade impeller is built and fitted with four electrodes. A number of challenges associated with operating a rotating electrode array have been addressed including a wireless communications protocol. The impeller has been accurately modelled and measurement simulations closely correspond to those acquired using the array. The apparatus has been used to successfully visualize a test distribution to a consistent standard compared to a conventional EIT electrode array and strategy. Presently, the limiting factor to this approach is the necessary high measurement acquistion rates which lead to restricted impeller velocities.