VEHICLE INTEGRATION OF BREATH ALCOHOL DETECTION SYSTEM
KEA TECHNOLOIGES INC.
(LITTLETON, MA)
Project Summary:
Designed and deployed a custom breath alcohol detection system integration for a fleet of Subaru Foresters as part of a pilot program with Washington State. The system included a breath inlet, snorkel, sensor, sensor bracket, user feedback components, and data acquisition hardware, all installed into the vehicle interior with the design intent of a seamless inte.
This project is part of a recurring vehicle integration program in which I have designed and deployed custom breath alcohol detection system integrations across multiple vehicle platforms, including the Subaru Forester, Ford F-350, Ford Explorer, and Chevrolet Malibu.
I was the sole mechanical designer responsible for system integration, BOM generation, custom component design, fabrication coordination, kitting, and deployment support.
The program was executed as a low-volume production run of five vehicles to support a Washington State pilot program for demonstration, public outreach, and field data collection.
Note: Due to confidentiality restrictions, detailed CAD models and prototype images are not shown on this site. Public demonstration footage and media coverage are available for interview review.
OBJECTIVES & REQUIREMENTS
The system integration was required to meet the following objectives:
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Seamlessly blend into the vehicle interior without drawing user attention
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Efficiently guide breath samples from the user to the sensor
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Position the inlet close to the driver’s natural breath path
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Minimize snorkel length to reduce sample dilution and response time
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Provide clear user feedback through visual indicators
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Enable user interaction for LED brightness adjustment
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Support reliable installation across multiple vehicles
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Allow on-site installation of the first vehicle
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Enable remaining kits to be shipped and installed remotely
CONSTRAINTS & DESIGN CONSIDERATIONS
The design was developed under several practical constraints that influenced material selection, geometry, and system layout:
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Tight packaging constraints around the steering column and instrument cluster
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Limited space for inlet geometry, snorkel routing, and sensor placement
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Need to minimize snorkel length to preserve breath sample integrity
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Requirement to avoid interference with existing vehicle components
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Risk of incomplete or imperfect OEM CAD data
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Manufacturing capacity limits for in-house additive production
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Need for repeatable installation across multiple vehicle model years
These considerations informed early design decisions, integration strategy, and validation planning.
CONCEPT & DESIGN APPROACH
The design approach focused on integrating the breath alcohol detection system into the vehicle interior while minimizing visual impact and maintaining reliable breath sample collection.
Based on prior vehicle integrations, the instrument cluster area was identified as the optimal inlet location due to its proximity to the driver’s breath path and its ability to naturally guide airflow. Alternative locations were assessed, but packaging constraints and user interaction considerations led to selecting the instrument cluster as the preferred integration point.
OEM CAD data was provided in STL format and imported into Onshape, where it was converted into a solid model to support accurate design integration. The provided geometry did not exactly match the production vehicle component, requiring minor geometry adjustments and fit refinements during the design process.
Rather than attaching a standalone inlet, the inlet was integrated directly into the instrument cluster bezel, allowing the modified bezel to replace the original vehicle component. The inlet was designed to be as deep as possible without interfering with steering column movement, and a hex-pattern feature was incorporated to disguise the inlet as a ventilation feature.
Internally, sloped geometry was used to guide the breath sample efficiently toward the snorkel, which was routed to the sensor location with minimal length to reduce breath dilution and response time.
The modified bezel was split into two components and produced using in-house MJF 3D printing in Nylon 12, which was selected for its strength, surface quality, and suitability for a low-volume production run. Additive manufacturing enabled rapid fit checks and iteration using the vehicle available on-site.
Sensor placement was evaluated across multiple locations, with the final mounting position selected in the rear left corner of the driver footwell, where an existing fastener could be used to secure a custom-designed bracket. The bracket provided rigid support while avoiding interference with vehicle systems.
To provide user feedback, the system incorporated an LED indicator to communicate system states (e.g., ready for breath, alcohol detected, no alcohol detected). A dedicated mounting groove was designed into the instrument cluster bezel to house the LED strip at a controlled depth. The groove geometry was tuned to position the LEDs close enough to the surface for visibility while allowing space for a diffuser to soften and distribute the light output.
A custom 3D-printed LED diffuser was designed to rest within the groove and enclose the LED strip. The diffuser was tinted prior to installation to reduce glare and minimize visual distraction for the driver. A user-facing push button was also integrated into the system to allow manual dimming of the LED output.
This same design philosophy—prioritizing seamless integration without sacrificing functionality—was applied across additional vehicle platforms.
ENGINEERING ANALYSIS & DESIGN VALIDATION
Engineering validation focused on confirming breath capture effectiveness, geometric fit, and installation robustness prior to releasing the design for fleet deployment.
Breath capture effectiveness was validated through a structured benchmarking process using multiple test participants of varying heights. Directed breath performance of the inlet was evaluated by delivering breath samples from a range of distances, typically between 5 inches and 30 inches, to assess capture consistency, sensitivity, and breath dilution factor. A baseline system check was first performed to confirm that the data acquisition system and sensor were correctly detecting breath input.
Benchmarking results showed that the integrated inlet performed consistently with existing inlet designs previously validated in other vehicles. Based on these results, the design was deemed suitable for in-field deployment.
Geometric fit and packaging validation were conducted in multiple stages due to limited availability of full OEM CAD data. An initial outer-frame test print of the inlet was produced and installed in the vehicle to verify that the proposed inlet footprint did not interfere with surrounding vehicle components. During physical fit-checking, it was discovered that the provided CAD geometry of the instrument cluster bezel did not exactly match the production vehicle component. A uniform gap of approximately 2 mm was observed between the rear frame of the bezel and the instrument cluster glass. To correct this, the bezel geometry was thickened to eliminate the gap, and minor adjustments were made to the mounting hole locations to improve alignment and overall fit. After confirming clearance of all other vehicle components with this initial test print, the internal inlet geometry and snorkel path were developed.
A second printed version of the instrument cluster bezel with the integrated inlet was produced and fit-checked in the vehicle. During this process, a minor modification was made to the snorkel geometry to angle it more directly toward the sensor location to improve breath flow alignment.
The sensor bracket was similarly validated through iterative fit checks. A printed bracket was evaluated with an installed sensor to confirm secure retention and proper orientation. During vehicle installation, the mounting arm angle was refined to better align the sensor with the adjusted snorkel path, minimizing overall distance and improving the directness of airflow from inlet to sensor.
Functional checks were also performed to confirm proper operation, visibility, and user adjustability of the LED indicator and push-button input following installation.
These validation activities ensured that the integrated system met functional performance requirements while maintaining reliable installation geometry and packaging compatibility.
MANUFACTURING, PROTOTYPING & ITERATION
This project was executed as a low-volume production run consisting of five complete vehicle kits across varying model years. All custom mechanical components—including the breath inlet integrated into the instrument cluster bezel, snorkel, sensor bracket, and LED diffuser—were produced using in-house additive manufacturing. MJF 3D printing was selected for the primary components due to its strength, surface finish, and suitability for short-run production, while SLA printing was used where finer detail was required.
Prototyping followed an iterative fit-check-driven approach. Initial test prints were used to verify clearances and identify potential interferences within the vehicle due to limited available CAD data. Subsequent iterations refined internal geometry, snorkel routing, and sensor alignment to improve breath capture efficiency and packaging. Minor adjustments were made to component geometry to account for differences between the provided CAD model and the as-built vehicle interior.
I generated the mechanical BOM, coordinated with the electrical team on shared components, and handled component kitting, packaging, and shipment of the remaining kits for off-site installation. The first vehicle was installed on-site to validate the integration approach, after which the remaining kits were shipped for installation in Washington State.
RESULTS, PRODUCTION STATUS & SKILLS
Results and Production Status:
All five systems were installed successfully and have been operating reliably in the field for nearly a year. The breath inlet design demonstrated strong and consistent performance across users of varying heights and seating positions, with breath capture results comparable to other validated vehicle integrations. The system has been used in public demonstrations and pilot programs, generating positive customer feedback and increased visibility for the technology.
The program is currently ongoing, supporting long-term data collection and evaluation of sensor performance in real-world conditions. This work is intended to inform future reference designs for broader deployment, including potential manufacturer-level integration rather than aftermarket installation.
This project demonstrates strengths in customer-facing system integration, low-volume manufacturing, and ownership of end-to-end delivery—from design through field deployment. Key skills highlighted include designing within tight spatial constraints, balancing aesthetics with functionality, rapid prototyping, installation planning, BOM management, and cross-functional collaboration.
Skills Demonstrated:
Tools and methods used included Onshape for CAD design, MJF and SLA 3D printing, component kitting and logistics coordination, in-vehicle fit checks, and field validation testing.