Evaluation methods and instruments of dry biopotential electrodes

Dry biopotential electrodes (DBPE) are suitable for measuring biopotential in longterm health monitoring systems due to simpler operation and less skin irritation than wet electrodes in the application process. So far, no uniform test standard and instrument was performed for evaluating the quality of dry electrodes. In this chapter, measurement methods and instruments for evaluating the quality of dry biopotential electrodes were reviewed systematically. These measurementmethods and instruments were classified into two categories: (1) common methods and instruments and (2) special methods and instruments. Properties of dry biopotential electrodes were summed up in the following several aspects: electrical conductivity, electrochemical impedance spectra, contact impedance, appearance, crystal texture, open circuit potential (OCP), biopotential signal noise and dynamic open circuit potential (DOCP), and so on. With progress of materials and electronics technology, more and more novel dry electrodes will be developed, and corresponding evaluation methods and instruments will also be fabricated.