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Background
I am
from the small town of Lampasas, TX, about 70 miles
from the University of Texas. I received my B.S. in
Chemical Engineering from UT. I am coadvised by Dr.
Peppas and Dr. Thomas Edgar. In my spare time I
enjoy spending time with my wife and daughter,
playing chess and poker, and watching the Longhorns.
Research Summary
Diabetes Mellitus currently affects more than 170
million people worldwide. Type I diabetes,
characterized by the inability to sufficiently
produce insulin to control glucose levels, is
especially dangerous, as it can cause sever
complications such as blindness, kidney failure, or
even death. To prevent these complications, tight
glucose control is required. The problem of using
insulin to control blood glucose levels falls
naturally into the realm of process control, where
one or more manipulated variables is dynamically
changing in order to tightly control one or more
controlled variables. Control can be either
open-loop, where somebody intervenes to control the
system, or closed-loop, where the system regulates
itself.
The
effectiveness of the control system depends strongly
on the accuracy of the process model being used to
develop the control sequence. The most common type
of model used to describe insulin and glucose
dynamics is the compartmental model, in which the
body is divided into various compartments, and
unsteady state material balances are written for
each one. Using Bergman’s 3 state model and
Sorensen’s 19 state model, we have demonstrated that
linearization of a nonlinear model results in a loss
of model accuracy significant enough to be able to
observe dramatic differences between the two when
feedback control is applied. We have also
demonstrated that traditional PID and feedforward
control cannot successfully control blood glucose in
a diabetic patient. Therefore, improvements in both
modeling and control are necessary.
My
research focuses on applying process modeling and
control techniques towards the development of
improved implicit closed-loop glucose responsive
insulin release systems. These systems will be used
in the development of novel therapies for Type I
diabetes mellitus. Specifically, I aim to develop
improved compartmental models describing insulin and
glucose dynamics for both healthy and diabetic
patients. Advanced control techniques will be
applied to the new models in order to develop
improved implantable insulin pumps. Release
dynamics from biodegradable hydrogel systems will
also be implemented into the model in order to
investigate the effectiveness of implicit
closed-loop control systems. Finally, time will be
spent in the laboratory developing hydrogel systems
that are predicted by the models to give an optimal
insulin response to changes in the glucose
concentration.
Publications
T.G. Farmer, T.F.
Edgar and N.A. Peppas, “Modeling and Control of the
Behavior of Glucose Sensing Devices”, in N.A.
Peppas, K. Anseth, A.K. Dillow and C.E. Schmidt,
eds., Advances in Biomaterials, Bionanotechnology,
Biomimetic Systems and Tissue Engineering,
231-234, AIChE, New York, NY, 2004. Refereed. |
