Various embodiments include composite wicks for ultra-low noise condensation particle counters (CPCs). In one embodiment, a composite wick includes a first porous material having a first pore density, with the first porous material further having a first surface and an opposing second surface. A second porous material is in fluid communication with the first porous material and has a first surface with an area substantially the same as an area of the first surface of the first porous material. The first surface of the second porous material is substantially in contact with the first surface of the first porous material. The second porous material has a pore density that is dissimilar the first pore density of the first material. The first material and the second material are configured to provide vapor from a liquid to a fluid-based particle counter. Other apparatuses are disclosed.