Custom-designed electrochemical test systems allow for specific measurements to be generated for isolated variables in advanced materials testing. A well designed first-principle system can give insight into more complex interactions often found in real-world devices. Often, such isolated test systems utilize sub-systems that draw upon external reactants for sustained testing and exhaust reaction products as a result. Practical limitations on delivery of purified feed streams and mediation of exhaust require system operation that can fail unexpectedly, often as a result of failure of the system itself rather than of the materials under investigation.

A novel system for testing of zinc-air fuel cell cathodes is presented as an example system that allows for total internal flows of reactant and product chemical flows. Such systems allow for cyclic purification and analysis of reaction products and establishment of a device in which the only output of the testing is heat and reliable data.

Examination of test system control of state properties and elimination of suspected system contaminants highlight the benefits of the developed self-contained flow systems. Insight into general design characteristics for robust electrochemical test systems are developed in light of the limitations of the presented entropy machines.