Team Members:

Joe Bothwell Communicator

Kelly Toy Team Leader

Jon Cappel BWIG

Karim Mahamud BSAC

Client:

Jack Jiang, M.D., PhD

Division of Otolaryngology

UW Medical School

Advisor:

John Webster, Ph. D

Biomedical Engineering

A device to atomize medication (water) molecules to sizes ranging from 5 to 20 µm. This is most easily achieved by modifying existing jet nebulizers to create particle sizes to our specification.

ABSTRACT

PROBLEM STATEMENTThe goal of this project is to

develop a device that can selectively produce liquid particles in the range of 5 to 20 µm. This device should safely and accurately produce the particles with precision of 10% to the desired mean.

BackgroundThere is a lot of research available on

spray technologyMost medical atomization devices are

designed to target the lower respiratory system.

Particle size affects the location of distribution, particles smaller than 5 µm tend to bypass the larynx.

MOTIVATIONAvailable devices tend to be quite complex, and

expensive. It would be ideal to select a specific particle size

to analyze the different effects it has on the larynx.

Conduct research to determine which way to atomize particles is the best.

Product Design Specification Dispense liquid (water) particles of sizes

ranging from 5-20 µm Portable Simple design, easy to use. Reliable to ± 10% for 6 months or 400 uses Adaptable as an inhaler to channel

medication directly to patient. Should be ergonomically pleasing to

patients

Variables effecting Particle Size

A larger orifice creates larger particle sizes.

Higher pressure creates smaller particle sizes.

Large Orifice

Small Orifice

Design Alternatives

Modification of Salter Labs Nebulizer

Modification of Pari LC Plus Nebulizer

Pressurize liquid though restricted flow.

Salter Labs 8900 Nebulizer

Nebulizes at 7 L/min in horizontal or vertical position

Large surface area provided by convex cone

Designed to maximize output

Residual volume 1.7 mL Low cost of $2.99

Pari LC Plus Nebulizer

2 valves to deliver medication

Maximizes aerosol delivery, minimizes waste

Delivers 20 L/min in 6.5 to 8.5 minutes

Residual volume 1.4 mL Cost $14.95

http://www.allergy4less.com

Pressurize liquid through restricted flow.

Depends on mechanical force of pressureDepends on size of orifice of spray valveEffective differences require pressure

gradients on the scale of several hundred PSI

Malvern Particle Size Detector

Used to measure particle sizes of sprays, dry powders suspensions, and liquids

Can measure particles from 0.1µm to 1mm

Can take a reading once every .4 milliseconds

Design MatrixSalter Labs Pari LC

PlusPressurized Flow

Simplicity 5 6 7

Reliability 5 6 5

Ease of Modification

6 7 4

Ease of Use 6 6 3

Total 22 25 19

Chosen Design: Pari LC Plus Nebulizer

Has a more simple design, most easily modified

Lower residual volumeHigher output

Results

Pari LC Plus Salter 8900

10 PSI 9.36µm 8.89µm

15 PSI 8.78µm 7.89µm

20 PSI 8.16µm 7.34µm

25 PSI 7.25µm 6.64µm

Future work- Salter 8900 Nebulizer

Baffle shears liquid File down baffle Larger particles are

able to passBaffle structures

www.mbsollc.com/inservice5.asp

Future work- Pari LC Plus Nebulizer

Increase clearance

Increase size of orifice

Results in larger particle size

http://www.allergy4less.com

References Dr. A Rawle, Basic principles of particle size measurement, Malvern Instruments

limited 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. J. Aerosol Sci.  2000;Sep:S787-

s789. 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/ Dolovich M., Labiris N., Pulmonary drug delivery. Br. J. Clin. Pharmacol.

www.blackwell-synergy.com/links/doi/10.1046/j.1365-2125.2003.01893.x/full 1 March 2004

Prakash Prashanth Ravi Prg. Ast-Grader/Reader, Engineering Experiment Station Malvern Instruments

www.malvern.co.uk/malvern/ondemand.nsf/frmondemandview