“…This result indicated that the purpose of early research on EIT hardware was to improve the EIT image quality [‘contrast’ and ‘distinguishability’ ( Adler et al, 2011 ) ] through the cooperation of hardware (‘electrode model’ ( Mueller et al, 1999 )) and algorithm (‘state estimation’ ( Kolehmainen et al, 2001 ) and ‘decomposition’ ( Clay and Ferree, 2002 )). Recent keywords mainly focus on the performance improvement of each module of EIT hardware system by applied new designs or techniques, including ‘voltage measurement’ ( Fu et al, 2022 ; Shi et al, 2022 ), current source (‘Howland current source’ ( Oh et al, 2011 ), ‘current driver’ ( Hong et al, 2010 ; Shahghasemi, 2020 )and ‘output impedance’ ( Shishvan et al, 2021 )) and novel electrode sensor (‘textile electrodes ( Katashev et al, 2018 ; Hu et al, 2021 )’ and ‘active electrode’ ( Wu et al, 2019 )). For example, Saulnier et al and Liu et al designed a DSP-based current source and a FPGA-based adaptive different current source in order to meet the requirement of high output impedance for current source in the most popular EIT hardware frameworks with a parallel and multiple source architecture ( Saulnier et al, 2020 ; Liu et al, 2021 ).…”