Author: Maryna Kavalenka

I got some new data on the pnc-Si capacitive sensor that has not been published on the blog yet. All of the results are summarized in the Spring MRS Proceedings paper mrsspring09_kavalenka. I also uploaded presentation that I made on MRS in “Presentations ” section of the blog. I will talk more about this data…

First, last week I had some images taken with new “visiting” AFM. These were frontside of the membrane with parylene deposited from the well side and the front side with deposited parylene on it. 1-1. Parylene deposition was not successful and although the dummy wafer showed thickness of parylene about 22nm, I suspect the were…

PDMS/membrane deflection was measured on Veeco profiler by JP and me. The main problem with this kind of measurement is that it is taken form the backside of the membrane and the walls need to be excluded from the measurement. Using 20x objective helps but still has some problems. PDMS was first spin-coated on the…

The last few times the spinned PDMS layers were much more uniform. The first picture below is with 1:100 diluted PDMS layer coated on it and the second one is a clean sample from the same wafer for comparison. The PDMS layer on the first picture is approximately 60nm thick. The measured thikness produced by…

As I told at the meeting, I tried spincoating PDMS on the membrane and it worked without breaking membrane. To make an ultrathin polymer film by spincoating the polymer has to be diluted in the particular solvent first. I used PDMS with elastomer to curing agent ratio (10:1) diluted in hexane (and xylene) by weight…

I mostly finished re-processing the images with new method of using pore processor. The images of molar flow/porosity dependence with older and newer processed data are below. Older image: New image: They don’t look much different. Also you can not compare them point by point because the porosity is different for both images after re-processing….

I attached a presentation here for tomorrow’s meeting. sensor

There is AFM images that were taken in Krauss’s lab before I left. I wasn’t able to see open pores. There were samples from two wafers (213 and 398) with deposited polymer. On samples from first wafer, the polyimide deposited very well and surface is smooth. On w398 the polyimide layer has hills which are…

The 20nm deposited polymer film permeability is approximately 1e6 barrers, while bulk polyimide permeability is less then 100. So the experimental value is too high. There are two possibilities to explain it: First, the pores are partially open and 20 nm thick layer is too thin to cover big pores. I will try AFM this…