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

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

3.  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 ◦ Currently used in:  UV protection (sunscreen)  Odor control in cat litter ◦ UV-activated to reduce odor (photocatalyst)

5.  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.  Operational Characteristics ◦ Sanitation ◦ Deodorization  Safety ◦ UV caution ◦ Fire precautions  Reliability and Efficiency

7.  Soap and water  Rubbing alcohol sanitation

8.  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.  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.  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.  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) Sheep’s Blood Agar

12. 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.  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 FactorsWeightDegradation Test Germ TestOdor Test SafetyMustYes Germs180163 Degradation181513 Odor12369 Wattage effect8643 Exposure effect8775 Repeatability1816149 Cost6532 Time1251011 Total100576145

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

16.  Allen, John, Dr. Client meeting. 18 Sept. 2007.  Common Microbiological Media. MadSci.org. 13 Oct. 2007.  Introduction: Bacterial Skin Infections: Merck Manual Home Edition. Feb. 2003. 13 Oct. 2007.  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/i stockphoto_408331_soap_and_water.jpg  http://www.life.umd.edu/classroom/bsci424/PathogenDescriptions /StreptococcusImages.htm