1. Nephrotex Dialysis MembraneTeam members: Pierce Hadley
Kunal Berry Katherine Kiang
Caroline Blassick Hannah Kuhl
Summary of Decision
Radar Graph for Selected Prototypes
Summary of Design Process Results from Testing
Group C, Team 2
A dialyzer is a medical device used for performing
hemodialysis mechanically through a porous membrane. A
dialyzer consists of solution-filled tube surrounding a
membrane, through which blood is pumped [1].
Hemodialysis uses diffusion, or the flow of a substance
from areas of high to low concentration, to act as a
mechanical kidney for those whose kidneys don't properly
function [2]. Hemodialysis has two main functions: To
remove metabolic waste from the blood and to maintain
water- electrolyte balance in the body. Electrolytes are
chemicals, such as potassium, chlorine, and sodium, that
dissolve in blood and perform a number of important
biological functions [1], [3].
Although hemodialysis has been practiced for decades,
hemodialysis patients continue to show lower quality of
life and higher risk of mortality than the general
population, prompting the need for faster and safer
hemodialysis [4], [5].
Our goal was to improve dialysis patients’ safety and
quality of life by creating a more efficient, cost-effective,
and safe dialysis membrane by experimenting with
different materials, surfactants, manufacturing processes,
and carbon nanotube (CNT) concentrations. A surfactant
is a material applied to the surface of the membrane to
improve performance by allowing organic compounds to
dissolve more easily, while carbon nanotubes are
cylindrical carbon molecules useful in improving the flow
rate and reliability of a dialysis membrane [6].
Hydrophilic
surfactant adds
reliability to our
design while
minimizing cost
Material Reliability Marketability Cost Flux Rate Blood Cell
Reactivity
PMMA N/A N/A N/A N/A N/A
PSF 7 500,000 90 21 65.56
PESPVP 11 600,000 130 13 43.33
PAM 9 600,000 110 19 43.33
PRNLT 9 800,000 130 21 65.56
2% Carbon Nanotube
Concentration maximizes flux
and provides a good balance
of reliability and marketability
PAM (Polyamide)
material may be high
cost, but it provides
excellent flux and blood
cell reactivity
The Dry-jet Wet
manufacturing process
reduces cost without
bringing blood cell reactivity
and flux too low.
# Material Process Surfactant % CNT
1 PMMA Phase Steric Hindrance 6.0
2 PSF Phase Steric Hindrance 1.0
3 PESPVP Vapor Steric Hindrance 15.0
4 PAM Dry Jet Wet Hydrophilic 2.0
5 PRNLT Dry Jet Wet Steric Hindrance 4.0
[1] Nephrotex, How Dialysis Works , Background research on dialysis , p.1 - 1
[2] Nephrotex, Introduction to Diffusion , Background research on dialysis , p.1 - 1
[3] Kirschbaum, B , The effect of hemodialysis on electrolytes and acid–base parameters , Clinica Chimica Acta , vol
336 , no 1-2, p.109 - 113
[4] Kalantar-Zadeh, K, Association Among SF36 Quality of Life Measures and Nutrition, Hospitalization, and
Mortality in Hemodialysis , Journal of the American Society of Nephrology , vol 12 , no 12, p.2797 - 2806
[5] Guerini, R , Multidimensional health-status assessment of chronic hemodialysis patients: the impact on quality
of life. , Europa Medicophysica , vol 42 , no 2, p.113 - 119
[6] Nephrotex, Hemodialytic Filtration Glossary, Background research on dialysis , p.1 - 3
[7] Nephrotex, Summary of Five Attributes, Graphing Surfactant Data , p.1 - 1
[8] Delgado, A , "Internal Consultants' Requests". RetrievedNovember , 2014 Available:
Image Credits:
[Image 1] "How Dialysis Works" Www.nephrotex.com. Web. 22 Nov. 2014.
[Image 2] "Introduction to Diffusion." Www.nephrotex.com. Web. 22 Nov. 2014.
[Image 3] “Radar Graph from FEEDS testing.” www.nephrotex.com. N.p., n.d. Web.
[Image 4] “Membrane Diagram from FEEDS.” www.nephrotex.com. N.p., n.d. Web.
Background: "Dna_desktop_1920x1080_hd-wallpaper." Http://www.hdwallpaperspics.com. Web. 22 Nov. 2014
Reliability: Refers to how long a dialysis membrane can perform before
falling below 75% of its maximum flux. Reliability is measured in hours
[7].
Marketability: Measures the expected commercial success of the
prototype, on a point scale [7].
Cost: Expense required to produce each unit, measured in dollars [7].
Flux Rate: Measures how quickly blood flows through the dialysis
membrane. Measured in m^3 / (m^2 - day) [7].
Blood Cell Reactivity: Measures the body’s immune response during
hemodialysis, in units of nanograms of activated blood components per
milliliter [7].
The PAM prototype was chosen for meeting
the highest number of consultants’
preferred values in addition to all of their
basic requirements. Although the prototype
failed to meet one preferred requirement in
cost, marketability, and blood cell reactivity,
it was close to the cutoff point in all cases.
The product’s high flux means faster
treatment time for the patient, while its low
cost and blood cell reactivity result in safe
and affordable care. With the addition of its
high marketability, the PAM prototype
provides the perfect balance between
business success and patient satisfaction.
Summary of System Testing Criteria
This prototype was developed in a multi-stage process. Each member of the
design team came in with knowledge of a particular membrane material,
which was based off of prototype testing with another group. After a group
meeting outlining the design goals and criteria, each member used this
knowledge to create the best design they could. Then each design was tested
in Nephrotex’s Electronic Experimental Device Simulator in order to find
which material design prototype had the best results.
Design Diagram
Above: A diagram illustrating blood flow
through the dialyzer [Image 1].
Below: Dialysis membrane allow waste
and electrolytes to diffuse while keeping
blood cells inside the bloodstream [Image
2].
[Image 3]
[Image 4]
Design
Attribute
Required Values for
Each Consultant [8]
Preferred Values for
Each Consultant [8]
Met by Prototype?
Reliability >1.5 (Michelle)
>5 (Alan)
>8 (Michelle)
>9 (Alan)
All
Marketability >250,000 (Wayne)
>400,000 (Rudy)
>650,000 (Wayne)
>550,000 (Rudy)
All but Wayne’s
Preferred
Cost <$120 (Rudy)
<$140 (Alan)
<$110 (Rudy)
<$95 (Alan)
All but Rudy’s
Preferred
Flux Rate >10 (Padma)
>12 (Michelle)
>17 (Padma)
>13.5 (Michelle)
All
Blood Cell
Reactivity
>75 (Padma)
>90 (Michelle)
>40(Padma)
>65 (Michelle)
All but Padma’s
Preferred
References