Biofilm Destructive System
Deborah Ohiani-JegedePartners: Nkele Davis and Nick
XydisGroup 24 , Client :Brad Clay, bio Merieux
Biofilms are an aggregate of microorganism where cells are stuck to each other and/or a surface
Can form contact lens cases due to improper cleaning/user non-compliance
Contact lens contamination can lead to microbial keratitis, conjunctivitis, staphylococci which may require surgery
Demonstration of Need
UsabilityWithin 3” x 5”Weight: < 5 lbOperating time: < 1 hoursVisual timer displaySet up Time: < 30
secondsSound during application:
< 40 dBAutonomous system,
turns on and off automaticallyWaterproof
Economics Cost: < $200 (prescribed by
doctor) Power Draw: < .25kWhr per
application Effectiveness
95% biofilm destruction biofilm growth prevention No damage to lens case and
lens Durability
meets all other specification requirements after 5 years
Design Requirements
Choose Disinfection Technology
Disinfection Technologies Hydrogen Peroxide
Solutions Heat Treatment Pulsed Electric Field Ultraviolet Radiation Sonication Atmospheric Pressure
Room-Temperature Plasmas
Overview of Design Alternatives
Construct Final Product Design
UV-C radiation (100-280nm) effectively stunts biofilm growth
Penetrates bacteria to nucleus to irreversibly damage the DNA
254nm breaks molecular bonds of microsomal DNA
Ultraviolet Radiation
High frequency shaking (sonication) can disrupt biofilm by breaking up extracellular matrix and dislodging from surface
Coupled with another method, could potentially make disinfecting more effective
Sonication at 40kHz for 5minutes had success in previous literature
UV Radiation + Sonication
Apply high voltage between dielectric electrodes to ionize surrounding air
Reactive oxygen species (O3, H202, O2, OH-) destroys biofilms via oxidation
“Plasma needle” – high voltage to metal wire to ionize surrounding air
Cold Plasmas
Analysis Performed to Choose Design Tested UV radiation, UV + Sonication, Cold
Plasmas Staph epidermidis - test bacteria
oCommon microbe on contact lens and contact lens cases
oBiofilm forming strain chosen oDiluted bacteria to 1McFarland (3e8 bacteria/mL)
Testing on polystyrene coverslips oCommon plastic in contact lens manufacturing
UV Treatment UV-C radiation at 254nm
produced using MaxLamp FIlter
Three five-minute treatments biofilm on coverslip
Streaked samples on agar plates in between trials
Plates grown overnight in incubator at 36°C
Results from UV Testing
Extremely effective in destroying biofilms Solution added to coverslip to prevent
drying/warping
UV+Sonication Treatment
Prepared coverslip, placed in ultrasonic cleaner, and weighted down with bottle
Treated for 5 minutes at 40kHz, then with 5 min UV
Cycle repeated 3 times total Swab and plate samples after each
treatment Plates grown overnight in incubator
at 36°C
UV+Sonication Results
Cold Plasma Treatment Small hole bored into petri
dish cover contain plasma Generator at 30kV Three five-minute treatments
of plasma Swab and plate samples
after each treatment Plates grown overnight in
incubator at 36°C
Cold Plasma Results
UV vs. Plasma Comparison
Pugh Chart Weight Ultraviolet
Radiation
Ultraviolet Radiation + Sonication
Cold Plasma
Efficacy 5 5 3 3Safety 4 4 4 3
Durability 4 4 3 3Cost 3 3 2 4
Speed of Use 2 5 4 3
TOTAL 76 57 57
Choosing a Final Design
Motor engine to sonicate
UV+SonicationPlasma
Chosen Design Deep UV light Single Button Timer Display Safety Interlock Door sensors LED Light Minimal light intensity
of 30 microWatts/cm2
30-minute application Side Panel Access Door
Group Responsibilities Nkele
oSonication and Mechanical Turbulence ExpertoLead Ergonomics Designer
Deborah oUV Treatment and Biofilm Growth ExpertoLead Mechanical Designer
NickoPlasma and Electric-Field Treatment ExpertoLead Electrical Designer
Design Schedule November
o 2nd - Optimizing Physical Designo 4th - Performing UV Wavelength Testingo 5th - Continued Wavelength Testing o 6th - Ensuring Optimal UV Application
Technique o 7th - Evaluation of Experimental
Resultso 8th - Meet with Manufacturingo 10th - Computer Model of Designo 13th - Brainstorming compatible
materialso 15th - Creating official List of Materialso 16th - Design Verificationo 22nd - Final Paper Drafto 28th - Thanksgivingo 29th - Final Paper Revision
Decembero 2nd - Final
Presentationo 4th - Final
Report Dueo 5th -
Celebratory Retreat
Questions?