Lateral-Flow Dipstick (LFD)

A lateral-flow dipstick (short: LFD) is a detection platform based on the lateral-flow principle. This is capillary forces move a liquid along the surface (= lateral) of a membrane.

Neither use nor read-out of a LFDs require a device: the liquid transport is done by capillary forces and the read-out is possible by the human eye. Expensive detection technique is not required.

A lateral-flow dipstick comprises of several so-called "pads" and a membrane:

1. The "sample application pad" (SAP): here the liquid to analyse is applied which may contain the molecules to detect.
2. The "conjugate release pad" (CRP): contains dried particles with marker molecules conjugated to it's surface. The liquid to analyse dissolves these particles. The molecules to detect bind to the marker molecules and thus to the particles.
3. The lateral-flow membrane: here further marker molecules are immobilized in lines. The membrane transports the particles with the liquid stream which pass these marker molecules. If the molecules to detect bind also to these markers, then the particles stick to these lines. Thus the particles accumulate at the lines which is visible by the human eye.
4. The "wicking pad" (Wick): This is the pad where the liquid flows to. It hinders the liquid to flow back into the membrane.

Usually a lateral-flow dipstick has two lines on the membrane: a test line and an assay control. The assay control checks if the conjugate, i.e. the binding between particles and it's marker molecule is still intact.

AMODIA offers several variations of lateral-flow strips, which differ in the number of detectable amplification products.