The aerolayer: airborne filtration by aerodynamic focusing and growth

In this work, a novel approach for airborne filtration with particular reference to medical (non-oil) medical mask is discussed. Here, and contrariwise to current approaches, filtration is attained neither by reducing the hydraulic diameter of the pore nor by increasing the fibre layers thickness-both of them with a strong penalty in the breathability of the mask, but rather by aerodynamic focussing and growth of the particles themselves. Aerodynamic focussing of particles is achieved by a proper simple parallel rearrangement of the traditional crisscrossing fibres-a configuration which we called the aerolayer; and the growth by coalescence. Utilizing a simplified geometrical and physical model, an expression for the required length of the aerolayer was derived. It is shown that the aerolayer is not only able to increase the probability of capture for small particles but also can potentially improve the breathability by reduction of the total thickness of the current layers required. Additional R &D is required in order to arrive to the most optimized practical design of the aerolayer.