On the Stability of Porous Platinum Coatings for In-Ear EEG Applications

Challenging applications, like in-ear electroencephalography (EEG), call for small electrode geometries with a large active area. Porous platinum (pPt) coating is a promising candidate, whereby the stability and reusability remain pressing manners. Here, different seeding layers were examined to find the most stable base substrate. In all cases the pPt reduced the impedance by two orders of magnitude in the low frequency region (<; 100 Hz), and the atomic concentration of platinum was preserved with 85%wt. Roughening of the materials by hatching or using medical alloys like MP35N leads to increased abrasion after peeling tests. Smooth platinum or platinum-iridium (90/10) performed best and withstood up to 2 MPa peeling force.