The size of the apertures changes along the membrane’s thickness, with the greatest openings appearing on one side and the smallest openings on the other. Each side of the membrane appears slightly different when viewed with reflected light at low incidence angles. In comparison to the side with the smallest pores, the side with the greatest pores will appear more matte or dull (which will appear shinier).

The majority of people can quickly distinguish the sides if they have some experience. Without effecting retention, the membranes can be utilized with either surface pointed upstream. However, pointing the bright side upstream enables more accurate examinations of the retained particles while orienting the dull side upstream boosts overall throughput.

At Sanitek, we pay attention to the details of every link and strictly adhere to ISO 9001:2008 and ISO 13485:2005 standards to ensure the quality of our products.

In the raw material procurement phase, we work with reliable suppliers to ensure that the quality of raw materials meets our standard requirements.

In the production process, we strictly control the quality of each link to ensure that the manufacturing process of the product is stable and reliable. At the factory inspection stage of the final product, we carry out a comprehensive quality check to ensure that the product meets the customer’s requirements and specifications.

In case of any issues, Sanitek will respond promptly to assist you in analyzing the problem and finding out the cause. We retain the raw material of all shipments, which is essential for identifying if the issue originates from the membrane. While incidents are extremely rare, if the problem is confirmed to be from the membrane, we will take corrective action, including prioritized full replacement of the affected lot.

Hydrophilic membranes readily absorb water due to surface tension, allowing water to flow through their pores. These filters are commonly used for water and aqueous solutions but are unsuitable for air or gas filtration, as they would block flow if wetted.

Hydrophobic membranes, on the other hand, repel water, preventing it from entering the pores unless pressure exceeds a certain threshold. These filters are typically used for air, gas, or non-aqueous fluid filtration. When used with water, hydrophobic filters must first be pre-wetted with a compatible fluid to allow water flow.

PES membrane filters offer low protein binding, making them an excellent choice for applications like tissue culture media sterilization, as well as in life sciences and microbiology. Their unique properties ensure minimal interference with sensitive fluids, maintaining the integrity of the solution.

Nominal pore size ratings offer a general indication of filter retention but may allow particles equal to or slightly larger than the rated size to pass through. These ratings can vary between manufacturers and may not always represent identical retention capabilities.

Absolute pore size ratings, on the other hand, are determined through retention tests using known microorganisms or particles, indicating the smallest size fully retained by the filter. These ratings are more consistent across manufacturers and are often tied to bubble point specifications. However, application conditions can still affect particle retention, even for filters with absolute ratings.

PES membrane filters are generally not suitable for lateral flow assays due to their low protein binding capacity. Lateral flow applications typically require membranes that can bind proteins more effectively.