Design and construction of the Artificial Patient module for testing bioimpedance measuring devices

The purpose of this study was to describe the design of the electronic module for testing bioimpedance measuring
devices, for example impedance cardiographs or impedance pneumographs. Artificial Patient was conceived as an
electronic equivalent of the impedance of skin-electrode interface and the impedance between electrodes – measured
one. Different approaches in imitating a resistance of skin and an impedance of electrode-skin connection were
presented.
The module was adapted for frequently applied tetrapolar electrode configuration. Therefore the design do not enclose
the elements simulating impedance between skin and receiver electrodes due to negligible effect of this impedance on
the current flow through the receiver.
The Artificial Patient enables testing either application generators, or receiver parts, particularly the level of noise and
distortions of the signal. Use of digitally controlled potentiometer allows simulating different tissue resistances changes
such as constant values, very-low-frequency and low-frequency changes corresponding to those caused by breathing or
heart activity. Also it allows distorting signals in order to test algorithms of artifacts attenuation.