This Strange Filter Only Lets Big Things Through

Reverse filter lets bigger things through, hold back smaller things, by using an improbable membrane that can have many uses in the future. Separation of substances is central to many industrial and medical processes ranging from wastewater treatment and purification to medical diagnostics. Conventional solid-based membranes allow particles below a critical size to pass through a membrane pore while inhibiting the passage of particles larger than that critical size; membranes that are capable of showing reversed behavior, that is, the passage of large particles and inhibition of small ones.