Prosthesis Disinfectant and Deodorizer

1
Prosthesis Disinfectant and Deodorizer

• Andrew Bertram, Aaron Freis, Jenna Spaeth, Jason
  Tham
• Client Dr. John Allen

2
Background

• Prosthetic silicone liners
• Fit over stump
• Direct contact with skin
• Currently cleaned with mild soap and/or alcohol
• Current problems
• Infection
• Odor

3
Kelly Light-UV irradiation

• Daughter uses UV light to disinfect prosthetic
• Ultraviolet Lamps
• Irradiates microbes
• Currently used in
• Air filters
• Water purification (Philips)
• Hazardous to skin and eyes

4
Titanium Dioxide

• Titanium Dioxide
• Currently used in
• UV protection (sunscreen)
• Odor control in cat litter
• UV-activated to reduce odor (photocatalyst)

5
Problem Statement

• Prosthetic liners must be sterilized and
  deodorized daily to prevent infection
• Current cleaning process time consuming and
  inefficient
• Testing
• Degradation of silicone liners due to UV
  radiation
• Effectiveness of sanitization by UV radiation
• Optimal wattage of UV light bulb and duration of
  exposure
• Odor reduction by titanium dioxide

6
Design Constraints

• Operational Characteristics
• Sanitation
• Deodorization
• Safety
• UV caution
• Fire precautions
• Reliability and Efficiency

7
Competition

• Soap and water
• Rubbing alcohol sanitation

8
Silicone Degradation Test

• Silicone hyper-sensitive to UV-irradiation
• As radiation increases the silicone material
  will
• Increase in hardness
• Increase in tensile strength, then later sharply
  decline and fail
• Decrease in elongation
• Will UV-irradiation affect the properties of the
  silicone, preventing the maximum time-use of the
  prosthetic liners?

9
Preliminary Testing

• Took old used liners (6 months of use)
• Subjected to 1 hour of UV-irradiation per day for
  two weeks
• Observations
• No physical signs of degradation
• Silicone was heated from exposure limits
• Must use tensile testing to get quantitative data

10
Degradation Testing

• Exposure of two liners to UV-irradiation
• Time and distance
• Observe visible properties failures
• Cracks, tears, hardening, temperature change
• Use tensile test to examine elongation and
  tensile strength
• Examine over weeks

11
Microbial Content Test

• Four samples
• UV-treated liner
• Alcohol swabbed liner
• Washed liner (mild soap)
• Control liner (no cleansing)
• Potential bacteria used
• Staphylococci
• Streptococci
• Grown in agar gel
• (shown at right)

Sheeps Blood Agar
12
Microbial Testing Process

1. Culture and apply bacterial strain to 8 pieces of
   liner
2. Apply sterilization method
3. Rinse with deionized water into agar dish
4. Culture for 48 hours
5. Investigate growth

13
Titanium Dioxide Odor Test

• Setup array of test samples
• Expose to varying intensities of UV and titanium
  dioxide
• Cleanse second set of samples with soap and
  alcohol
• Judge odor strength with sniff survey

14
Test Matrix
Test Factors Weight Degradation Test Germ Test Odor Test
Safety Must Yes Yes Yes
Germs 18 0 16 3
Degradation 18 15 1 3
Odor 12 3 6 9
Wattage effect 8 6 4 3
Exposure effect 8 7 7 5
Repeatability 18 16 14 9
Cost 6 5 3 2
Time 12 5 10 11
Total 100 57 61 45
15
Future Work

• Decide on test strategies
• Design/build test setups
• Begin testing and analysis
• Refine test setups and procedures
• Retest and conclude

16
References

• Allen, John, Dr. Client meeting. 18 Sept. 2007.
• Common Microbiological Media. MadSci.org. 13 Oct.
  2007 lthttp//www.madsci.org/lynn/micro/media/gt.
• Introduction Bacterial Skin Infections Merck
  Manual Home Edition. Feb. 2003. 13 Oct. 2007
  lthttp//www.merck.com/mmhe/sec18/ch211/ch211a.html
  gt.
• Odom, Jason. "Prosthesis Disinfectant." E-mail to
  Aaron Freis. 3 Oct. 2007.
• http//content.answers.com/main/content/wp/en/8/8e
  /Germicidal_UV_discharge_tube_glow.jpg
• http//www.kinesys.com/retailers/images/mini-kids-
  spf30_cream.jpg
• http//www1.istockphoto.com/file_thumbview_approve
  /408331/2/istockphoto_408331_soap_and_water.jpg
• http//www.life.umd.edu/classroom/bsci424/Pathogen
  Descriptions/StreptococcusImages.htm