Biofilm Destructive System

Deborah Ohiani-Jegede

Partners: Nkele Davis and Nick Xydis

Group 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 bacteriaoCommon microbe on contact lens and contact lens

casesoBiofilm 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

  WeightUltraviolet Radiation

Ultraviolet Radiation + Sonication

Cold Plasma

Efficacy 5 5 3 3

Safety 4 4 4 3

Durability 4 4 3 3

Cost 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?