Transcript Mechanical Testing Coupled with and Environmental Chamber for

Mechanical Testing
System Coupled with an
Environmental Chamber for Hydrogels
Team: Charlie Haggart, Gabriel J. Martínez-Díaz,
Darcée Nelson, and Michael Piché
Client: Weiyuan John Kao, Ph.D.
Advisor: Paul Thompson
BME 402 Midsemester Presentation
3/7/03
Overview






Problem Statement
Background Information
Previous Work
Current Progress
Future Work
Acknowledgements
Problem Statement

To design and build an environmental
chamber to be used with a mechanical
testing system to observe the tensile
and creep properties of hydrogels
under varying physiological conditions
Background Information

Hydrogels




Cross-linked polymeric
structures
Can absorb water or
biological fluids
Properties change with
pH and temperature
Applications include
drug delivery vessels
and wound/burn care
Design Specifications


Mechanical properties of hydrogels
must be characterized in physiological
conditions (pH = 4-8 and 37 °C)
Interested in tensile and creep
properties to understand the behavior
of hydrogels in varying conditions
Previous Work: Tensile Testing

Environmental
chamber was
built to be used
with Instron 1000
Previous Work: Creep Testing



Instron 1000
incapable of creep
testing
No other
commercially
available devices
exist
Creep chamber
was built last
semester
Present Work: Tensile Testing


Conducted tensile testing with
environmental chamber and Instron
1000
Environmental chamber met
specifications (maintained
physiological conditions, compatible
with Instron 1000)
Present Work: Tensile Testing


Instron 1000 not sensitive enough to
measure tensile properties of
hydrogels tested
System may be used for future testing

Different materials (i.e. rat skin)
Present Work: Creep Testing

Problem


Grips were
difficult to adjust
Solution

New grips were
ordered from
McMaster-Carr
1“
Present Work: Creep Testing

Problem


Chamber too small
to fit hands into,
making sample
adjustment difficult
Solution

Modified tensile
chamber, in order
to be used for
tensile AND creep
tests
Present Work: Creep Testing
Pulley system
will be added
here
Weight stand
Bottom grip
attached
Acrylic cylinder
added that forms
tight seal with oring
Acrylic cylinder
to stabilize
LVDT
Chamber
positioned onto
creep base
Future Work




Modify grips for use in creep testing
system
Attach pulley apparatus
Data acquisition
Validation of creep testing system
Acknowledgements





Professor Kao
Paul Thompson
Bill Hagquist, ME Shop
Jeff Schowalter, ECE Dept.
BME Dept.