Electrochemical Sensing with Spatially Patterned Pt Octahedra Electrodes

Locally controlling the position of electrodes in 3D can open new avenues to collect electrochemical signals in complex sensing environments. Implementing such electrodes via an electrical network requires advanced fabrication approaches. This work uses corner lithography and Pt ALD to produce electrochemical 3D electrodes. The approach allows the fabrication of (sub)micrometer size Pt octahedra electrodes spatially supported over 3D fractal-like structures. As a proof of concept, electrochemical sensing of ferrocyanide in biofouling environments, e.g., bovine serum albumin (BSA) and Pseudomonas aeruginosa (P. aeruginosa), is assessed. Differences between before and after BSA addition show a reduction in the active electrode surface area (Delta Aeff) approximate to 49% +/- 7% for the flat electrode. In comparison, a Delta Aeff reduction of 25% +/- 2% for the 3D electrode has been found. The results are accompanied by a 24% +/- 16% decrease in peak current for the flat Pt substrate and a 14% +/- 5% decrease in peak current for the 3D electrode 24 h after adding BSA. In the case of P. aeruginosa, the 3D electrode retains electrochemical signals, while the flat electrode does not. The results demonstrate that the 3D Pt electrodes are more stable than their flat counterparts under biofouling conditions. A fabrication method for the spatial patterning of Pt octahedra is introduced. Electrochemical sensing is carried out to demonstrate the electrochemical readout capabilities of the Pt octahedra under biofouling conditions. In the near future, the technology can habilitate local electrochemical sensing over a Pt octahedron in more complex cellular environments.image