micro - and nanofilters have a wide range of applications in many fields , including medical diagnostics , drug delivery , medical implants , and hemodialysis . some issues that limit commercial application of current nanofilters in medicine are low pore density , non - uniform pore size , and the use of materials that are not biocompatible . a method is described to fabricate high porosity polymer and diamond micro - and nanofilters producing smooth , uniform and straight pores of high aspect ratio . pore size , density , and shape can be predetermined with a high degree of precision by masks and controlled etch . the method combines energetic neutral atom beam lithography and a mask . this technology allows etching polymeric materials in a clean , well - controlled , and charge - free environment , making it very suitable for fabricating nanofilters and other components for biomedical applications .