Highly Porous Platinum Electrodes for Dry Ear-EEG Measurements

The interest in dry electroencephalography (EEG) electrodes has increased in recent years, especially as everyday suitability earplugs for measuring drowsiness or focus of auditory attention. However, the challenge is still the need for a good electrode material, which is reliable and can be easily processed for highly personalized applications. Laser processing, as used here, is a fast and very precise method to produce personalized electrode configurations that meet the high requirements of in-ear EEG electrodes. The arrangement of the electrodes on the flexible and compressible mats allows an exact alignment to the ear mold and contributes to high wearing comfort, as no edges or metal protrusions are present. For better transmission properties, an adapted coating process for surface enlargement of platinum electrodes is used, which can be controlled precisely. The resulting porous platinum-copper alloy is chemically very stable, shows no exposed copper residues, and enlarges the effective surface area by 40. In a proof-of-principle experiment, these porous platinum electrodes could be used to measure the Berger effect in a dry state using just one ear of a test person. Their signal-to-noise ratio and the frequency transfer function is comparable to gel-based silver/silver chloride electrodes.

Investigation of Structural, Optical, Electrical, and Biological Properties of a Porous Platinum Electrode for Neurostimulation Devices

The structural and optical properties, as well as the electrical and biological characteristics of a porous platinum (Pt) structure for neurostimulation applications, are investigated. Critical factors such as biocompatibility, electrical performance, and structural and optical differences, which can adversely affect the functionality of implantable devices, are systematically analyzed and compared with general electrodes. By employing an integration of three-dimensional simulations and implantation experiments, we demonstrate that the remarkably extensive surface area, low reflectance, and outstanding peak current values inherent in porous Pt facilitate effective stimulation while simultaneously ensuring a high degree of biological safety. Our findings suggest that these beneficial characteristics collectively position porous Pt as a notably promising candidate for implantable electrodes in biomedical devices.