Biosensor Biofouling & Signal Drift: 2D Diffusion-Path Simulator

An implanted electrochemical biosensor only reports what actually reaches its electrode, and what reaches the electrode changes the moment it is implanted: adsorbed tissue proteins and a maturing fibrous capsule form a biofouling shell that lengthens the diffusion path analyte molecules must cross. This 2D companion to the 3D biosensor simulator keeps the same real Fick's-law diffusion-path model — the fouling layer's thickness follows a saturating growth curve, and sensitivity decays as its inverse — but renders it as a clean top-down cross-section you can pan and zoom, and adds a live true-vs-reported concentration strip chart with no 3D equivalent, so the slow divergence between what the sensor reports and what is actually in the blood is visible as a graph, not just a percentage. A recalibration only zeroes the current offset rather than reversing the underlying drift, and only replacing the sensor resets the fouling clock to zero.