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Diffusion 101


If diffusion studies are new to you, perhaps you’ve been assigned one and you have no idea where to begin, please read Diffusion Cell Basics for terms, definitions and background information.  Once you have an idea of how to proceed but feel some additional guidance would be helpful, you can download our Diffusion Testing Fundamentals primer to help you learn what is required for a proper study and begin to design one. For comprehensive membrane and selection guidance, please view the following documents:

For further assistance, please email us at: [email protected]

Basics for Ordering

If you plan to use Franz Cells and you’re not sure how to proceed, here are some practical basics to consider:

  • 1 – Franz Cell experiments are generally run at an elevated temperature. You can use your Franz Cells in an incubated environment, or you can purchase jacketed cells and connect them to a source of warming water, a water bath and pump, or heater/circulator. Jacketed cells are more expensive, but using them out of an incubated hood is less cumbersome especially in a V-Series Stirrer.
  • 2 – What orifice diameter is best? For human skin, 9mm is strongly recommended because it’s large enough to provide reliable data but small enough to accommodate skin specimens that aren’t too costly. For mucosa, 5mm is appropriate because it’s often difficult to obtain specimens suitable for larger cells. For all other membranes any size orifice will do, 15mm is the most common size for polymeric membranes.
  • 3 – What receptor chamber volume will work?  The receptor volumes of our standard cells will provide good data for a majority of experiments. However, there are always exceptions, and we can often provide receptor chamber volumes that will generate better data for those occasions when the standard cells aren’t ideal.  It seems to hold true that the larger the ratio of the orifice area to the receptor volume, the better the results will be.  Therefore, generally, it is desirable to make the receptor chamber volumes as small as possible. (Some researchers have requested much larger than standard volume receptor chambers even so.)  If you have determined that receptor volume is critical to your work, we can likely provide a more suitable Franz Cell in the unjacketed variety as the heating jacket presents constraints where practical glassblowing is concerned.  For a given orifice diameter, it is much easier to achieve a smaller than standard receptor volume in an unjacketed cell.