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Mist Generator

Mist Generator. http://www.rcjournal.com/contents/06.00/06.00.0609.asp. Kelly Toy Jon Cappel Joe Bothwell Abdikarim Mahamud. Advisor – John Webster Client – Jack Jiang, MD, PhD. Overview. Problem Statement Background Material

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Mist Generator

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  1. Mist Generator http://www.rcjournal.com/contents/06.00/06.00.0609.asp. Kelly Toy Jon Cappel Joe Bothwell Abdikarim Mahamud Advisor – John Webster Client – Jack Jiang, MD, PhD

  2. Overview • Problem Statement • Background Material • Summary of product design specifications • Design Alternatives considered • Future Work

  3. Problem Statement • Research being conducted on the larynx can be benefited by the specific targeting of medication in the respiratory system • Specific targeting of medication is difficult to complete accurately • The process of atomizing particles is complex

  4. Client Requirement -Product is needed that can: • Generate a mist of different densities • Generate particle sizes in the range of 0.5-50 microns • Adaptable as inhaler • Generate mist such that different areas of the respiratory system can be targeted

  5. Background • Different ways to generate mist: • Ultrasonic Nebulizer • Micropumps • Pressure activated devices • Particle measurement techniques

  6. Ultrasonic Nebulizer • Converts electricity into ultrasonic waves • Transducer vibrates at frequency of waves (1-3 MHz) • Higher the frequency, smaller droplets • Transducer generates ultrasonic fountain of liquid • Aerosol delivered by fan or inspiration • Creates particles ~1-6 microns Dennis J, Hendrick D

  7. Ultrasonic NebulizerAdvantages/Disadvantages Advantages • Stable particle size • Small dead volume • High aerosol output • Quiet • Fast drug delivery Disadvantages • Aerosol solution can become heated • Expensive • Short cycle life (600-1000 uses)

  8. Micropumps • OnQ is one of the micropumps used in the market for nebulizers. • contains over a thousand precision-formed tapered holes, surrounded by a vibrational element. • plate vibrates over 100,000 times per second. • It draws liquid through the holes to form consistently sized droplets. • Problems • How to adjust the frequency. http://www.aerogen.com

  9. Pressure Activated Devices • Devices that create mist by using pressure • Inhalers use a similar principle • hand-held portable devices that deliver medication directly to the lungs • Uses pressurized canister with chemical propellant http://www.aaaai.org/patients/allergic_conditions/metered_dose_inhalers.stm

  10. Pressure Activated Devices • Devices similar to hairspray bottles • Use pressure to compress liquid • Liquid is compressed through tiny opening creating mist http://www.drugstore.com/ http://www.atomization.de/basic.htm#Physical

  11. Pressure Activated Devices • Advantages • Inexpensive • Simple • Disadvantages • Comparatively, very large mist particles • Different nozzles needed for different densities

  12. Particle measurement techniques • Laser Diffraction • Method is absolute, no need to calibrate instruments • Wide range .01-2000 microns • Flexibility, paint nozzle sprays to dry powder • Can measure circulating liquid particles. • Requires expensive equipment • Engine research lab has a Malvern laser diffraction instrument • Microscopy • Relies on microscope, and precision measuring devices. • Somewhat prone to error due to the judgment of the operator.

  13. Particle measurement techniques • Cascade impactor • Progressively filters out smaller particles through a series of tubes. • Particles accumulate according to their size, and the concentrations are analyzed after the experiment • Can take a relatively long time to complete • Electrozone sensing • Changes in capacitance are measured as a charged particle flows through a small opening. • Extremely difficult/near impossible to measure sprays.

  14. Design Alternatives 1.Modify a Nebulizer • Adjust pressure input • Adjust vibration frequency • Apply a charge to solution • Adjust opening size • Particle size selector • Requires monetary investment

  15. Design Alternatives 2.Create our own simple device • Use the most simple aspects of fluid mechanics • Obtain an actuator, and force liquid through it at different pressures. 3.Purchase existing components • May require slight modifications • Extremely expensive

  16. Design/Decision Matrix

  17. Final Design Choice • Create our own simple device. • We will force liquid through different sized actuators, and experimentally determine what size and pressures will obtain the required particle size. • Easy to modify if needed • Relies only on pressure and actuator opening

  18. Future Work • Obtain different sized actuators • Develop a method for subjecting liquid to specific pressure levels. • Develop a prototype • Perform experiments • Analyze results.

  19. References • Basic principals of particle size measurement, Dr. Alan Rawle, Malvern Instruments limited • http://www.tsi.com/particle/products/accessories/376060.htm • http://www.atomization.de/basic.htm#Physical • Hess D. Nebulizers: Principles and Performance.  Respiratory Care.  http://www.rcjournal.com/contents/06.00/06.00.0609.asp. 2 March 2004 • Dennis J, Hendrick D.  Design of drug nebulizers. Journal of Aerosol Science.  2000;Sep:S787-s789.this one is for picture • American Academy of Asthma and Allergy Immunity http://www.aaaai.org/patients/allergic_conditions/metered_dose_inhalers.stm 2004 • Aerogen, 2004 http://www.aerogen.com/

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