A membrane filter is a type of filtration device that uses a thin barrier, or membrane, to separate particles from liquids or gases. These filters are designed with tiny pores that allow certain substances to pass through while blocking others, making them effective for purifying water, air, and various industrial processes. Membrane filters are commonly used in laboratories and industries for applications such as sterilization, clarification, and separation of microorganisms. They can be made from various materials, including polyethersulfone and cellulose acetate, depending on the specific requirements of the filtration process.