Customized Filter Material Supports Innovation In The Medical Industry

Selecting customized expanded PTFE for medical filtration products pays multiple dividends. By R. L. Rama Chandra EDITED BY STEPHEN J. MRAZ Poro-Tex, a customizable expanded polytetrafluoroethylene material (ePTFE) from DeWAL Industries, has high tensile strength and is available in a range of uniform pore sizes and pore distributions. The density and width of the material can be customized, and its water-repellent, oil-absorbent, and dielectric properties can be altered. The material complies with FDA regulations for medical applications, and has a wide variety of uses in the medical and scientific industries. It has been used in blood filtration and other ultra and microfiltration applications, as well as in venting, in clean-room and medical garments, and in EMI/RFI insulation. In-line intravenous filters frequently use ePTFE as the filtration or venting material. Its porosity can be customized according to the end-use requirements. Because it is chemically inert, it is well suited for harsh chemical and biological environments. Billets of PTFE are extruded at a controlled temperature to ensure the resulting film is stable and homogenous. Bags are diestamped from a laminate of porous UHMW-PE and expanded PTFE. The bags are used to extract certain chemicals from samples using heated solvents. Expanded PTFE film is slit into the widths specified by the customer. The slit films are collected on cores prior to packaging and shipping. Expanded ePTFE emerges from a machine that expands it laterally under heat. Here the PTFE is being expanded from an initial width of 6.5 in. to a final width of 32 in. When it comes to specifying filter materials for medical and laboratory equipment, "one size fits all" and "best fit" are seldom both applicable. Almost every new filtration system presents a unique combination of working specifications for variables such as pressure, flow rate, and working temperature. Some lab applications,