Artificial Burning Limb

1
Artificial Burning Limb

• Team - Blake Hondl, Kristin La Fortune, and Liz
  Thottakara
• Client - Dr. Matt Halanski, UW-Hospital
  Orthopedic Surgery
• Advisor - Professor Justin Williams, Department
  of BME

2
Presentation Overview

• Background Information
• Revised Problem Statement
• Previous Design Work
• Prototype Modifications
• Materials and Cost
• Testing and Analysis
• Future Work

3
Background Information

• Cast Burn
• Curing process can potentially burn skin surface
• Time and temperature affect burn severity

4
Background Information

• Previous study examined factors that affect the
  internal temperature of cast curing
• Cast thickness
• Dipping water temperature
• Testing apparatus
• Pyrex cylinder
• Heated by water bath
• No real-time display

5
Revised Problem Statement

• The goal of this project is to design an testing
  setup that will allow our client to measure
• Effect of different factors (e.g. cast thickness,
  dipping water temperature, limb size, etc) on
  internal cast temperature
• Internal and external temperatures of a cast
  during curing
• Our client is also interested in measuring the
  internal and external cast temperature on human
  subjects

6
Previous Design Work

• Designed a system that includes
• Flexible carbon fiber heater to maintain skin
  temperature
• Thermocouples to measure internal and external
  temperatures
• Data logger and analysis software that displays
  and records temperature data

7
Heating Element

• Thermion carbon fiber heater
• Inexpensive
• Even heat distribution
• Designed for low temperature operation
• Two 7 x 15 connected in parallel

Carbon Fiber
Wire
8
Data Acquisition and Analysis

• Microdaq Data Logger
• Records up to 26,214 measurements per channel
• Four thermocouple inputs
• Internal memory chip
• Data Logger Software
• Displays and records real-time temperature data
• Simple user interface
• Windows via USB

9
Additional Client Specifications

• Varying size of limb structure
• Complete set of equipment for own lab
• Power supply sufficient to heat heaters between
  32 and 37C (skin surface temperature) and cables
• Need a supply that can provide at least 6V, 6A
• Additional thermocouples

10
Prototype Revisions

• New Arm Models
• 2 diameter PVC pipe
• (2) 6x6 carbon fiber heaters, 12V, 27W
• 1 ½ diameter PVC pipe
• 8x8 carbon fiber heater, 12V, 33W

11
Prototype Revisions

• Power Supply for heaters
• BK 1665 Bench Switching DC Power Supply
• 1-19VDC, 0-10A

12
Prototype Revisions

• Type T Thermocouples
• Sensitive to within 1C
• Less expensive
• Ideal for temperature range

13
Materials and Cost

• Thermion carbon fiber heaters - 125
• Physitemp thermocouples - 80 each
• Microdaq data logger and software - 600
• MadgeTech Thermocouples - 80
• Power Supply and cables - 210
• Limb Structure Materials - 60

14
Prototype Testing

• Power settings corresponding to appropriate
  temperature for heater
• Heater did not always level off at same
  temperature
• Client can manually adjust power until desired
  temperature is reached
• Plaster cast material
• Internal and external temperature

15
Prototype Testing

• Cast Thickness
• 6 layers vs. 3 layers of fiberglass casting
  material

16
IR Imaging of Heater

• Future Images need to measure temperature at 2
  points to find relationship between temperature
  and pixel intensity
• Account for difference in emissivity of skin and
  heater

17
Future Work

• Additional IR images with temperature scale
• Images of cast during curing
• Compare IR temperatures with thermocouple
  readings
• Assist with client testing and analysis of
  results
• Journal article