Mist GeneratorMist Generator

Kelly Toy Jon CappelKelly Toy Jon Cappel

Joe Bothwell Abdikarim MahamudJoe Bothwell Abdikarim Mahamud

Advisor – John Webster

Client – Jack Jiang, MD, PhD

http://www.rcjournal.com/contents/06.00/06.00.0609.asp.

University of Wisconsin - Madison Biomedical Engineering Design Courses

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4) Continued attendance at this presentation constitutes compliance with this

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OverviewOverview

Problem StatementProblem Statement

Background MaterialBackground Material

Summary of product design specificationsSummary of product design specifications

Design Alternatives consideredDesign Alternatives considered

Future WorkFuture Work

Problem StatementProblem Statement

Research being conducted on the larynx Research being conducted on the larynx can be benefited by the specific targeting of can be benefited by the specific targeting of medication in the respiratory systemmedication in the respiratory system

Specific targeting of medication is difficult to Specific targeting of medication is difficult to complete accuratelycomplete accurately

The process of atomizing particles is The process of atomizing particles is complexcomplex

Client RequirementClient Requirement

-Product is needed that can:-Product is needed that can:Generate a mist of different densitiesGenerate a mist of different densities

Generate particle sizes in the range of 0.5-50 Generate particle sizes in the range of 0.5-50 micronsmicrons

Adaptable as inhalerAdaptable as inhaler

Generate mist such that different areas of the Generate mist such that different areas of the respiratory system can be targetedrespiratory system can be targeted

BackgroundBackground

Different ways to generate mist:Different ways to generate mist:– Ultrasonic NebulizerUltrasonic Nebulizer– MicropumpsMicropumps– Pressure activated devicesPressure activated devices

Particle measurement techniquesParticle measurement techniques

Ultrasonic NebulizerUltrasonic NebulizerConverts electricity into Converts electricity into ultrasonic waves ultrasonic waves Transducer vibrates at Transducer vibrates at frequency of waves (1-3 frequency of waves (1-3 MHz)MHz)Higher the frequency, Higher the frequency, smaller dropletssmaller dropletsTransducer generates Transducer generates ultrasonic fountain of liquidultrasonic fountain of liquidAerosol delivered by fan or Aerosol delivered by fan or inspirationinspirationCreates particles ~1-6 Creates particles ~1-6 micronsmicrons

Dennis J, Hendrick DDennis J, Hendrick D

Ultrasonic NebulizerUltrasonic NebulizerAdvantages/DisadvantagesAdvantages/DisadvantagesAdvantagesAdvantages

Stable particle sizeStable particle sizeSmall dead volumeSmall dead volumeHigh aerosol outputHigh aerosol outputQuietQuietFast drug deliveryFast drug delivery

DisadvantagesDisadvantagesAerosol solution can become Aerosol solution can become heatedheatedExpensiveExpensiveShort cycle life (600-1000 Short cycle life (600-1000 uses)uses)

http://www.mabis.net/40-270-Open/

MicropumpsMicropumps

OnQ is one of the micropumps OnQ is one of the micropumps used in the market for used in the market for nebulizers. nebulizers. contains over a thousand contains over a thousand precision-formed tapered precision-formed tapered holes, surrounded by a holes, surrounded by a vibrational element. vibrational element. plate vibrates over 100,000 plate vibrates over 100,000 times per second.times per second.It draws liquid through the It draws liquid through the holes to form consistently holes to form consistently sized droplets. sized droplets.

Problems Problems How to adjust the frequency.How to adjust the frequency.

http://http://www.aerogen.comwww.aerogen.com

Pressure Activated DevicesPressure 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

Pressure Activated DevicesPressure Activated Devices

Devices similar to hairspray Devices similar to hairspray bottlesbottles– Use pressure to compress liquidUse pressure to compress liquid– Liquid is compressed through tiny Liquid is compressed through tiny

opening creating mistopening creating mist

http://www.atomization.de/basic.htm#Physical

http://www.drugstore.com/

Pressure Activated DevicesPressure Activated Devices

AdvantagesAdvantages– InexpensiveInexpensive– SimpleSimple

DisadvantagesDisadvantages– Comparatively, very large mist particlesComparatively, very large mist particles– Different nozzles needed for different Different nozzles needed for different

densitiesdensities

Particle measurement techniquesParticle measurement techniquesLaser DiffractionLaser Diffraction– Method is absolute, no need to calibrate instrumentsMethod is absolute, no need to calibrate instruments– Wide range .01-2000 micronsWide range .01-2000 microns– Flexibility, paint nozzle sprays to dry powderFlexibility, paint nozzle sprays to dry powder– Can measure circulating liquid particles.Can measure circulating liquid particles.– Requires expensive equipmentRequires expensive equipment– Engine research lab has a Malvern laser diffraction Engine research lab has a Malvern laser diffraction

instrument instrument MicroscopyMicroscopy– Relies on microscope, and precision measuring Relies on microscope, and precision measuring

devices.devices.– Somewhat prone to error due to the judgment of the Somewhat prone to error due to the judgment of the

operator. operator.

Particle measurement techniquesParticle measurement techniques

Cascade impactorCascade impactor– Progressively filters out smaller particles through a Progressively filters out smaller particles through a

series of tubes.series of tubes.– Particles accumulate according to their size, and Particles accumulate according to their size, and

the concentrations are analyzed after the the concentrations are analyzed after the experimentexperiment

– Can take a relatively long time to completeCan take a relatively long time to completeElectrozone sensingElectrozone sensing– Changes in capacitance are measured as a Changes in capacitance are measured as a

charged particle flows through a small opening.charged particle flows through a small opening.– Extremely difficult/near impossible to measure Extremely difficult/near impossible to measure

sprays.sprays.

Design AlternativesDesign Alternatives

1.Modify a Nebulizer1.Modify a Nebulizer– Adjust pressure inputAdjust pressure input– Adjust vibration frequencyAdjust vibration frequency– Apply a charge to solutionApply a charge to solution– Adjust opening sizeAdjust opening size– Particle size selectorParticle size selector– Requires monetary investmentRequires monetary investment

Design AlternativesDesign Alternatives

2.Create our own simple device2.Create our own simple device– Use the most simple aspects of fluid Use the most simple aspects of fluid

mechanicsmechanics– Obtain an actuator, and force liquid through it Obtain an actuator, and force liquid through it

at different pressures.at different pressures.

3.Purchase existing components 3.Purchase existing components – May require slight modificationsMay require slight modifications– Extremely expensiveExtremely expensive

Design/Decision MatrixDesign/Decision MatrixNebulizerNebulizer Our DeviceOur Device PurchasePurchase

AccuracyAccuracy 55 66 99

ComplexityComplexity

(ease of use)(ease of use)

55 88 33

PricePrice 55 77 11

Life spanLife span 66 66 77

TotalTotal 2525 2626 2020

Final Design ChoiceFinal Design Choice

Create our own simple device.Create our own simple device.– We will force liquid through different sized We will force liquid through different sized

actuators, and experimentally determine what actuators, and experimentally determine what size and pressures will obtain the required size and pressures will obtain the required particle size.particle size.

Easy to modify if neededEasy to modify if needed

Relies only on pressure and actuator openingRelies only on pressure and actuator opening

Future WorkFuture Work

Obtain different sized actuatorsObtain different sized actuators

Develop a method for subjecting liquid to Develop a method for subjecting liquid to specific pressure levels.specific pressure levels.

Develop a prototype Develop a prototype

Perform experimentsPerform experiments

Analyze results.Analyze results.

ReferencesReferences

Basic principals of particle size measurement, Dr. Alan Rawle, Malvern Basic principals of particle size measurement, Dr. Alan Rawle, Malvern Instruments limitedInstruments limited

http://www.tsi.com/particle/products/accessories/376060.htmhttp://www.tsi.com/particle/products/accessories/376060.htm

http://www.atomization.de/basic.htm#Physicalhttp://www.atomization.de/basic.htm#Physical

Hess D. Nebulizers: Principles and Performance.  Respiratory Care.  Hess D. Nebulizers: Principles and Performance.  Respiratory Care.  http://www.rcjournal.com/contents/06.00/06.00.0609.asp. 2 March 2004http://www.rcjournal.com/contents/06.00/06.00.0609.asp. 2 March 2004

Dennis J, Hendrick D.  Design of drug nebulizers. Journal of Aerosol Dennis J, Hendrick D.  Design of drug nebulizers. Journal of Aerosol Science.  2000;Sep:S787-s789.Science.  2000;Sep:S787-s789.this one is for picturethis one is for picture

American Academy of Asthma and Allergy Immunity American Academy of Asthma and Allergy Immunity http://www.aaaai.org/patients/allergic_conditions/metered_dose_inhalers.sthttp://www.aaaai.org/patients/allergic_conditions/metered_dose_inhalers.stm 2004m 2004

Aerogen, 2004 http://www.aerogen.com/Aerogen, 2004 http://www.aerogen.com/