[paper] Polymer Electrodes in Clinical EEG and MEG

Laura M. Ferrari, Usein Ismailov, Jean-Michel Badier, Francesco Greco and Esma Ismailova 

Conducting polymer tattoo electrodes in clinical electro- and magneto-encephalography

npj Flex Electron 4, 4 (2020)
Received: 17 October 2019; Accepted: 20 February 2020;

DOI: 10.1038/s41528-020-0067-z

Abstract - Temporary tattoo electrodes are the most recent development in the field of cutaneous sensors. They have successfully demonstrated their performances in the monitoring of various electrophysiological signals on the skin. These epidermal electronic devices offer a conformal and imperceptible contact with the wearer while enabling good quality recordings over time. Evaluations of brain activity in clinical practice face multiple limitations, where such electrodes can provide realistic technological solutions and increase diagnostics efficiency. Here we present the performance of inkjet-printed conducting polymer tattoo electrodes in clinical electroencephalography and their compatibility with magnetoencephalography. The working mechanism of these dry sensors is investigated through the modeling of the skin/electrode impedance for better understanding of the biosignals transduction at this interface. Furthermore, a custom-made skin phantom platform demonstrates the feasibility of high-density recordings, which are essential in localizing neuropathological activities. These evaluations provide valuable input for the successful application of these ultrathin electronic tattoos sensors in multimodal brain monitoring and diagnosis.

Fig: Temporary tattoo electrodes (TTEs) for EEG: a The layered structure of the temporary tattoo paper permits the release of the top film on which electrodes are fabricated. b Expanded view of an all-polymer printed TTE. c A TTE released on the scalp, in Oz position. d Close-in view of a TTE released on the scalp after 12 h from application. e Impedance recordings on the forearm using TTE and Ag/AgCl electrodes. 

Experiments involving human participants -Two able-bodied participants (one male and one female aged 33.5 ± 3.5 years old) free of any motor and neural disorders gave their informed consent and participated in this study. One participant performed the impedance recordings with the three diverse TTEs sets while another participant volunteered in the EEG/MEG evaluations with TTEs and Ag/AgCl electrodes. All experiments are performed following Timone hospital’s regulations regarding personal data protection. The experiment was conducted under conditions provided by French regulations.

Data Availability - The experimental data referenced in this text is available from the authors upon reasonable request.