Mechanical%20Testing%20System%20Coupled%20with%20an%20Environmental%20Chamber%20for%20Hydrogels

1
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

2
Overview

• Problem Statement
• Background Information
• Previous Work
• Current Progress
• Future Work
• Acknowledgements

3
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

4
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

5
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

6
Previous Work Tensile Testing

• Environmental chamber was built to be used with
  Instron 1000

7
Previous Work Creep Testing

• Instron 1000 incapable of creep testing
• No other commercially available devices exist
• Creep chamber was built last semester

8
Present Work Tensile Testing

• Conducted tensile testing with environmental
  chamber and Instron 1000
• Environmental chamber met specifications
  (maintained physiological conditions, compatible
  with Instron 1000)

9
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)

10
Present Work Creep Testing

• Problem
• Grips were difficult to adjust
• Solution
• New grips were ordered from McMaster-Carr

1
11
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

12
Present Work Creep Testing
Pulley system will be added here
Weight stand
Bottom grip attached
Acrylic cylinder to stabilize LVDT
Acrylic cylinder added that forms tight seal with
o-ring
Chamber positioned onto creep base
13
Future Work

• Modify grips for use in creep testing system
• Attach pulley apparatus
• Data acquisition
• Validation of creep testing system

14
Acknowledgements

• Professor Kao
• Paul Thompson
• Bill Hagquist, ME Shop
• Jeff Schowalter, ECE Dept.
• BME Dept.