In a classical amperometric experiment (e.g. chronoamperometry at a bare electrode), the analyte is consumed at the electrode–electrolyte interface, and the current is limited by mass transport. This leads to the formation of a diffusion layer.

However, I’m unsure whether the same concept of a diffusion layer applies in amperometric sensors based on immobilised enzymes, such as those using glucose oxidase (GOx).

Here’s my reasoning:

Therefore, I question whether a classical diffusion layer forms at the electrode in enzymatic sensors.