Using the very latest MEMs technology and processing techniques, we can now offer an array of holes, 2 µm in diameter on 4 µm centers. Due to compressive stresses in the silicon oxide membrane, wrinkling is prevalent and one we have not been able to fully conquer. Therefore to minimize the wrinkling that occurs, we have made these membranes with "reinforcing bars" left from the original silicon wafer. Instead of a single continuous window that is 500 µm, there are 25 separate windows with dimension of 75 µm on a side bordered by "bars" that are 25 µm wide.
The entire area of the membrane window, with the exception of the bar is in essence "holey" and the the array of holes cover the membrane area in its entirety. Quantitatively, in each of the 25 sectors there are 16 rows and 16 columns of perforations (2 µm holes on 4 µm centers) for a total of 256 perforations per sector, or 256 x 25 sectors for a total of 6400 perforations on each grid. The outside frame will fit comfortably in any TEM grid holder that has been designed for 3.05 mm diameter grids.
For applications involving the nucleation of nanofibers across the holes these SPI perforated membranes open up a whole new way of doing experiments since the population of holes is increased enormously.
Built into the silicon oxide perforated membrane window grid is an indexing system so that the same sector can be relocated for further study. Each sector can be described with its own unique set of indexing marks. (See photo at right)
These membranes are not flat. Waviness and wrinkling are a by-product of the manufacturing process and unavailable.
The typical TEM grid has a thickness of 30-50 µm whereas these membrane window grids are 200 µm thick. For most TEM users, this larger thickness presents no problems whatsoever. However, for the first time user, make sure you do not "force" the holder too tight. If you have a holder that is "too snug", we suggest contacting your TEM vendor supplier to see if your holder can be modified to accept a thicker grid.
