NPN as an integrated filter for a NP Sensor
Last fall we decided to try to integrate a filter immediately upstream of Vincent Tabard-Cossa’s nanopore DNA sensors. The idea is to assemble back-to-back a NPN membrane a standard nitride membrane used in Vincent’s nanopore fabrication system an oxide spacer.
Currently the lifetime of these sensors/sequencers is limited by clogging events. The purpose of our system is to catch any non-specific junk large enough to clog pores in our nanofilter.
After much back-and-forth we decided to move forward with a plan to integrate our existing NPN flow cell membranes with small area nitride membranes carrying various oxide spacers. Something like … 
Where the red indicates the oxide. The central small square is the nitride membrane and the rectangular area is our NPN flow cell format. The small squares in the corner are access vias we placed in the NPN flow cell chips.
Dimensions: The NPN filter chips are made on 310 um silicon. The nitride/oxide chips are on 200 um silicon. I believe the nitride membrane windows are 50 x 50 um.
The mask designs from SiMPore looked like this …
The posts are designed to prevent the two membranes from touching. Unfortunately the smaller high density posts did not resolve. So the two chips we actually have are low density posts and no posts.
The bonding fun will begin this week.
Vincent is sending us a copy of his new NP drilling chamber sized to fit our 5.5 mm chips. The drawings are here …
simpore chip holder base drawing
simpore chip holder base 2 drawing
Perhaps we can use this device to align the chips during bonding or we can try a compression strategy as done by the Protochips company.