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Frequently Asked Questions

Q:  I’ve been tasked with performing a diffusion cell study and I’ve never used a diffusion cell before. Can you help?

A: The first thing you need to do is decide which diffusion cell will work best for your study. Please read our Cell Selection Guide for assistance. After that, if you think you know which diffusion cell is needed but aren’t sure how to proceed, please read our Diffusion Cell Basics and Primer.


Q:  What is the difference between jacketed and unjacketed Franz Cells?

A: A jacketed Franz Cell is a diffusion cell with a “heating jacket” which is a glass chamber around the receptor chamber that allows circulated liquid, usually water, to maintain an other than ambient temperature in the receptor chamber.  An unjacketed Franz Cell is a diffusion cell without the heating jacket that may be placed in a temperature controlled environment to achieve the desired temperature, when other than ambient temperature is required.


Q: I’m working with human skin, what Franz Cell should I order?

A: You should use a Franz Cell with a 9mm orifice diameter, flat ground joint, and 5ml receptor volume. It is the de facto standard for working with human skin.  It may be used with any membrane 4mm or less in thickness.  Larger orifice diameter Franz Cells require bigger and therefore more costly skin specimens.


Q:  I will be doing corneal work, what type of joint do I need?

A: Franz Cells with a spherical (ball and socket) joint are ideal for corneal research.


Q:  What is In vitro diffusion?

A: In vitro diffusion is generally passive diffusion of a permeant from a vehicle in the donor chamber, through an artificial or biological membrane, into the membrane or through it into the receptor fluid in a receptor chamber.


Q: I broke the sampling arm on my Franz Cell, now what?

A:  Chances are it can be repaired for a nominal fee, send us a picture and we will make the determination.  The same applies for a broken port.


Q: OQ/PQ is due on my equipment, is this something I can do in house myself?

A: Yes, PermeGear offers a complete step-by-step packet that is ISO compliant.


Q: I want my Franz Cells to be certified and have serial numbers, can you do that?

A: Yes, PermeGear offers this service.


Q: What is the smallest possible receptor volume I can have with my cell?

A: 9mm / 3ml

11.28mm / 5ml

15mm / 6ml

20mm / 10ml

25mm / 15ml


Q: What are the rpms of PermeGear stirrers?  Do you offer variable speed?

A: According to the USP Chapter 1724 standards, 500 rpms are required in 50hz countries, and 600 rpms are required in 60hz countries – PermeGear equipment meets these requirements.


Q: What is the most common joint that people order?

A: The flat ground joint is the most commonly ordered joint, it is ideal for human skin and membranes 4mm or less in thickness


Q: Where can I acquire human skin for my study?

A:  There are many companies, below is a list of the companies we have dealt with and talked to:







Q: Can jacketed Franz Cells of different orifice diameters fit in the same V-Series Stirrer?

A: All PermeGear standard jacketed Franz Cells with orifice diameters up to 20mm fit in all PermeGear V-Series Stirrers.  25mm Franz Cells with flat ground joints also fit, but 25mm Franz Cells with flat flange joints do not, this is because of the Cell Clamps. However, PermeGear V3 and V9 full size Stirrers accommodate all standard jacketed Franz Cells.


Q: What is the smallest orifice diameter available in a Franz Cell?

A: 5mm – Also, please note that 5mm Franz Cells are only available with flat ground, o-ring, or spherical joints.  Flat flange joints cannot be ordered in a 5mm orifice diameter.