Pressure-driven flow

Pressure driven flow is a method to displace liquids in a capillary or microfluidic channel with pressure. The pressure typicalls is generated pneumatically by compressed air or other gasses (Nitrogen, Carbondioxide, etc) or by electrical and magnetical fields or gravitation.

physical fundamentals

It is known from thermodynamics that conjugated quantities scale in a different manner. Two classes can be distinguished: intensive quantities as temperature T, pressure P and amount of substance N or extensive quantities as entropy S, volume V and chemical potential μ. Extensive quantities scale with system size, whereas the intensive ones do not. The quantity pressure, for example, is defined as the (differential) quotient of two extensive variables: p=dE/dV (Energy E und Volume V) and therefore scal-independent as a scaling factor appearing in the nominator as well as the denominator just cancels out.