These well inserts are provided empty and designed to hold sample material, only. No membrane is included. It is comprised of 2 medical grade polycarbonate components - an inner and outer insert that are interlocking. The sample of choice (fiber, foil, membrane, textile, or tissue) is loaded. Kindly review the Technical Datasheet from Scaffdex Oy available at this link: https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/product/documents/355/007/cellcrown96.pdf
See the link below to review a publication that demonstrates one potential schematic:
https://www.nature.com/articles/s41598-020-68254-1.
The images below were taken from this article: