1. Lessons Learned
• Design of testing must be done early
• Timely and clear contact with vendors
• Final manufacturing must be
considered at all stages of the design
Arduino Uno used
to drive prototypes
Acknowledgements
Future Steps
1. Integrate into future breathalyzers
2. Perform U.S. DOT approval testing
3. Design assembly tooling
4. Develop proprietary design
Testing and Verification
How Does a Breathalyzer Work?
Pressure
Transducer
Sampling
System
Fuel Cell
Breath Flow
Sampling System Design 2: Bellows
Solenoid
• 4.5 mm stroke
length
EPDM Rubber Bellows
• Very inexpensive
ABS Housing
• Simple geometry
for manufacturing
Sampling System Design 1: Piston/Cylinder
Solenoid
• 4.5 mm stroke
length
Piston Adapter
• Self-aligning
(with O-ring)
Graphite Piston
• Small thermal expansion
• Self-lubricating
• Airtight
ABS Housing
• Simple geometry for manufacturing
Objective
To improve the reliability and
performance of Lifeloc’s FC Series
breathalyzer in order to penetrate
new markets
• Volume measurements needed with
a resolution of 1 mL (~1 grain of salt)
• Accomplished by relating change in
volume to change in pressure:
Pressure Transducer
used to translate
volume repeatability
ΔV = 𝑛𝑅𝑇
1
𝑃1
−
1
𝑃2
Low-Cost Breathalyzer Sampling System
Team 8: Joel Albin, Cayla Bluhm, Hayden Brian, Carl Marvin, Billy Olson, and Hunter Reid
Director: Dan Underkofler
Daria Kotys-Schwartz Nick Stites
Lee Mortimer Dan Godrick
G. Ravishankar Dan Underkofler
Glass Cylinder (with gasket)
• Small thermal expansion
• Low friction with graphite core
• Airtight
Volume: 150 mL
Est. Cost: $9
Volume: 80 mL
Est. Cost: $6
Piston/Cylinder (Preferred)
• More repeatable
• Adhesive free
• 6-7 total parts (longer assembly)
• Difficulties at high temperatures
Bellows
• $3 less expensive
• 3 total parts (plus adhesive)
• Ease of assembly
• Difficulties at high and low
temperatures
Percent Error in Volume
The sampling system pulls breath through the fuel cell which then measures blood alcohol content
Results
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Primary
 Volume repeatability within 1%
 Operate between -10° to 60° C
 Maximum 3 volts, 0.3 continuous
amps, and 1.0 burst amps
 Acid corrosion resistant
 Take 100,000 samples without failure
 Electronic indication of sample taken
Secondary
 Fit within current model casing
 Easily molded and assembled
 Minimum number of components
 Off the shelf components
 Total cost less than $11
Customer Requirements
ErrorinVolume(%)
Trial Number