Synkera offers both symmetric and asymmetric membranes made from nanoporous anodic aluminum oxide (AAO). Symmetric membranes have uniform cylindrical pores throughout the entire thickness of the membrane, with the same pore diameter on both faces of the membrane. Asymmetric membranes have uniform pores throughout most of the membrane thickness (base or support layer) ending in a thin layer (0.1-2 µm, depending on other specifications) with gradually reduced pore diameter and increased pore density (active layer).

                         Figure 1: SEM photo of the Active and Support/Base Layer

Normally, the membranes are packaged with the base layer facing up in the container.

If the orientation of a membrane is unknown, simple examination under a lamp with a clear glass bulb in which the filament can be observed will typically allow for differentiation.

• The active layer of the membrane will reflects more light and the image of the lamp/filament will appear blurry as shown in Figure 2.   The active layer is also characterized by a glossy, iridescent appearance.
• The base layer of the membrane allows less light to reflect from its surface than the active layer. This results in a more defined image of the lamp filament as shown in Figure 3. The base layer is also characterized by a dull, matte appearance.;

                                                                                                                                             Figure 2: Active Layer of Membrane                  Figure 3: Support Layer of Membrane

For more information on AAO membranes and other products, please visit our website at www.synkera.com. If you need additional information or to place an order, please contact us at: 720-494-8401 or info@synkera.com