Biomarker Discovery Simulator

Biosensor Assay

Sample concentration 1.0×

Assay sensitivity 0.60

Flow speed 1.0×

Background noise 0.05

Measured signal

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Bound sites

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Diagnostic call

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How it works

Biomarker molecules (orange) flow through a microfluidic channel and pass over an antibody array bonded to the sensor floor. Each pass over the array is a chance to bind — the probability follows Langmuir binding kinetics: the fraction of occupied sites rises with sample concentration but saturates once every antibody site is full, exactly like a real ELISA or lateral-flow assay reaching its dynamic-range ceiling.

θ = [C] / ([C] + Kd)
signal = Bmax·θ + noise
call = "positive" if signal > threshold else "negative"

Sample concentration — how much biomarker [C] is in the flowing sample; higher concentration means more molecules pass the array per second.
Assay sensitivity — inverse of the dissociation constant Kd; a more sensitive antibody captures molecules at lower concentrations, shifting the binding curve left.
Flow speed — how fast the sample moves past the sensor; too fast and molecules pass before they can bind, under-reading the true concentration.
Background noise — random non-specific binding (cross-reactivity) that raises the baseline signal even with no real biomarker present, the main source of false positives in real diagnostics.

Real-world relevance: this binding-and-saturation loop is the physical basis of troponin, PSA, HbA1c and antigen tests — clinicians read the plateaued signal against a validated threshold to call a result positive or negative, which is exactly what the "Diagnostic call" readout does here.

Free biomarker Bound to sensor Antibody array

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