Author: Dean Johnson
Dr. Johnson is a Research Assistant Professor in Nephrology who was awarded an R01 in 2020. He earned his Ph.D. in Microsystems Engineering from RIT and is currently working on hemodialysis devices based on the ultrathin nanoporous membranes developed earlier by this group.

I’ve looked at cloudiness from both sides now…

“I’ve looked at clouds from both sides now” is a Joni Mitchell song. Some Background We are developing a white blood cell (WBC) detector to surveil peritoneal dialysate fluid during fluid exchanges for early detection of peritonitis. This preemptive monitoring

Posted in NRG

COMSOL model of SiMPore Liftoff device

I drew an approximation of the SiMPore liftoff device and ran the COMSOL model with 1 mL/min urea fluid flow in the upper channels and 2 mL/min dialysate in the bottom channels. With this initial model, the urea was cleared

Posted in NRG

Instantaneous Clearance per unit area – Animal Study

We’ve calculated our instantaneous clearance numbers for the benchtop studies that use sepcon chips. Even calculating per unit area, our chips are not clearing much volume in these experiments. I believe this is due to the very low flow rate

Posted in Knowledge, NRG

Cellular Adhesion: Bare NPN v PEG NPN

In 5.4 mm single slot chips, sheep blood was flowed at 3 µL/min though the 3 mm x 1 mm channels with PBS flowed at the same rate but in the opposite direction for four hours. The chips were pre-wetted

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Study Proposal:In Vitro Cell Adhesion: Whole Blood, Single channel 5.4 mm chips

The purpose of this study will be to compare the cellular adhesion on PEG vs Bare nano porous silicon nitride membranes using the same fluidic devices as the in vitro clearance study. The devices will need to be disassembled for

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Kidney Week 2017

I recently attended ASN’s Kidney Week 2017 in New Orleans. I mostly ate beans and rice, although there are three completely vegan restaurants and several restaurants with vegan options. The music was terrific and the weather was terrific, the people

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2D COMSOL model of printed sepcon chip fixture

I created a COMSOL model (zip) model with geometry based on the CAD drawing of the sepcon fixture Jared provided. I’ve included Velocity results (then Concentration, Pressure, Vorticity, and Shear rate). Also included is the Parameter table which has the Diffusion

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Where oh Where can the holes in my 75 nm Membranes be?

Another set of images of both sides of a membrane, this time something weird is happening… It looks as though I’m missing some holes from the top side. They looked to be filled in but are not when seen from

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I’ve looked at 100 nm Membranes from both sides now…

While JK has been processing backside images from 50 nm, 75 nm, and 100 nm membrane SEM images for pore information, I thought I’d take a look at a 100 nm membrane from both the front and the back at

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Pore processing of one backside image of 75 nm thick membrane

Here is a better, more thoughtful, attempt at pore processing of a single image of the backside of a 75-nm thick membrane (four slot). One thing you will note that could be different from the analysis of the frontside of the

Posted in NRG
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