Ultimately we want to use SiN-NP filters to separate viruses or some other biological species, but repeated attempts to pass 20 nm fluorospheres in water or PBS have failed. Au particles, however, have passed through the filters. This post reports the results of Sarah and I attempting to pass Au particles from 20 to 100…
Following up on our previous work with SiN-NP with varied RIE times, Sarah and I measured permeability and permeance using a new measuring system better suited to the higher permeance and permeability we expect with the larger pores and higher porosity. Using the pressure regulator pictured above, we can set pressures of 3 psi and above…
JP and Josh Miller used the Xactic Si etcher to remove the pnc-Si from SiN-NP samples. I believe they ran cycles until the samples looked visibly like SiN only. Below are some SEM cross-sections showing before and after images of the samples. Sample 1028 with no RIE etch: Sample 1036 with 20 s RIE…
The following is a public service announcement: I’ve just aliquoted about 40mL of fluorescent BSA and placed it in the freezer. Each aliquot contains roughly 1mL of 6mg/mL TRITC-conjugate BSA, so there’s plenty of them. If anyone needs fluorescent BSA for anything, feel free to take as much as you need from the box labeled “TRITC-conjugate BSA”…
As I mentioned in my last post, I will be performing protein diffusion tests through CytoVu assemblies (from one well to the other) and measuring the amount of protein that is still in solution when the system reaches equilibrium in order to determine the amount of protein that is adsorbed to the assembly and thus…
This is a follow up to Mohammad’s previous posts: “Burst Pressure”, and “Burst Pressure Probability”. Josh and I had Mohammad’s wafer remade, and burst several 30nm thick pnc-Si TEM chips to add to Mohammad’s earlier data. Pore size still needs to be verified using the TEM. Burst pressure data was gathered for chips with constant perimeter,…
Continuing on the path of hemodialysis, we are increasing the complexity of the fluid being dialyzed. In this long-term experiment I will pump 100% serum with added urea (1mM) cytochrome c (1 mg/mL) and fluorescent BSA (1 mg/mL). So I need to detect urea, BSA, and cytochrome c in serum. Cytochrome c absorbs at 405…
I’ve performed what might be the last test of the n-Dodecyl β-D-Maltoside (“DDM”) coating. This time I washed for three minutes each sample in HBS just like in the reference, used precisely the same concentration (and type, for that matter) of protein that was used in the reference, and tested a positive control, a negative control,…
AFM images report Protocol: pnc-Si TEM grids were mounted on thin silicone inserts. Surface treatments were applied to the grids. Except for the CellTak treatment, the treatments were all diluted in Hank’s Balanced Salt Solution (HBSS) and incubated with grids for 2 hours and then washed off with PBS. CellTak was diluted in 0.1 M…
I’ve been using a Makerbot 2 for the last week or so, trying to see if we can use the same PDMS contact lithography techniques that we are all familiar with. In short, yes, but there is plenty of work to be done to make it a robust process for microfluidics. Makerbot Printer The…