Electric field gradients and bipolar electrochemistry effects on neural growth: A finite element study on immersed electroactive conducting electrode materials. (10th September 2019)

• Record Type: Journal Article
• Authors: Abad, Llibertat; Rajnicek, Ann M.; Casañ-Pastor, N.
• Is Part Of: Electrochimica acta. Volume 317(2019)
• Page Start: 102
• Page End: 111
• Publication Date: 2019-09-10
• Subjects: Electric gradients -- Neural electrodes -- Charge asymmetry -- Finite elements -- Electroactive materials -- Implants; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.05.149
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Implantable electrodes act with direct electrical contact although recent work has shown that electrostimulation is also possible through non-contact wireless settings, through the generation of dipoles at the borders of the material by bipolar electrochemistry. The experimental observations with neural cell cultures demonstrate a clear difference between insulator and conducting materials, but also between conducting and mixed conducting intercalation materials used as substrates of neural growth. Known bipolar electrochemistry effects may explain voltage profiles induced on conducting materials. Finite element studies shown here with the same configuration that the experimental processes described, evidence voltage profiles in qualitative agreement with known bipolar effects, although with a clear difference between intercalation materials and metals. Calculations also show a clear mapping of charge gradients at the material surface influencing growing neurons cells. While insulating materials only distort the electric field space distribution, the dipole generated at the borders of an implanted conducting material, inverted with respect to the insulating case, extends along the material interface, being relevant that is much smoother in intercalation materials. Mapping of the gradients as the distance is increased from the conducting material is also discussed. These observations may explain the differences in neural cell growth observed for various substrate materials. Graphical abstract: Image 1 Highlights: Finite element analysis shows inversion of voltage and charge gradient at immersed borders of conducting material. Intercalation materials show smaller and softer profiles of voltage and charge than gold. The dipolar effect extends to the whole material surface and reaches heights in the scale of neuron bodies. Finite element modelling envisages different charge and voltage gradients and spatial distribution for each material. Observations explain in vitro neural cell behavior in each material.