Development, fabrication, and applications of biomedical electrodes

Abstract

Biomedical electrodes convert the ion potential generated by electrochemical activities into an electronic potential that can be measured by instrumentation systems; they are widely used as sensors in modern clinical detection and biomedical measurement. In recent years, with increasing applications in the fields of electrocardiography (ECG), electroencephalography (EEG), electromyography (EMG), and electrical impedance tomography (EIT), a great number of new biomedical electrodes with novel structural design and new material selection have been explored and developed; low-cost fabrication methods are also being intensively studied. In this paper, biomedical electrodes are classified into five types, including traditional silver/silver chloride electrodes, microneedle electrodes, flexible textile electrodes, foam electrodes, and insulated dry electrodes. The conversion mechanisms from ion potential to electronic potential of different biomedical electrodes described in the prior literature are firstly introduced, and then the latest research results concerning the fabrication processes for different biomedical electrodes, and the methods of using them, are reviewed. The advantages and disadvantages of each type of electrode for practical applications are discussed, based on the published literature. A general description of the current applications of biomedical electrodes in ECG, EEG, EMG, and EIT is presented. Typical results from researchers in various countries are reviewed to further introduce the detailed application of different biomedical electrodes. Emerging application fields for biomedical electrodes, such as electrooculography, electrogastrography, and the study of the nervous system, are also presented. Finally, the development and application prospects of biomedical electrodes are described briefly. With the rapid development of microelectronics, micro-nano manufacturing and signal processing technology, the related manufacturing technologies and signal processing methods for biomedical electrodes have achieved great progress; in particular, a much deeper understanding about the contact mechanism with human tissue and skin has been obtained. We believe that many new biomedical electrodes will be developed in the next few years to greatly improve the detection level of bioelectric information.