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Brunel Jet Ventilator with the Acessory Box
Preterm infants with underdeveloped lungs require mechanical ventilation to breathe. The Brunel Jet Ventilator assists this process, but carries a 2lb accessory box that presents two compounding challenges. First, any sudden movement risks displacing the breathing tube, which is positioned with X-ray precision inside an infant's airway — a critical safety concern during skin-to-skin contact between parent and infant, a practice actively encouraged at Jacobs Medical Center to promote bonding and recovery. Second, the previous iteration of the senior project — constructed primarily from acrylic — failed within a year of deployment as sustained vibration caused internal components to fuse, raising concerns about long-term device reliability.
Effective vibration isolation was therefore necessary not only for patient safety, but for the mechanical longevity of the device itself.
Taking the lessons from the previous senior design team, our team redesigned the full mechanical arm system, the KangaArm, to allow safe maneuvering of the accessory box during skin-to-skin contact. The arm integrates a clamp, revolute joint, and vertical joint — allowing flexible positioning while keeping the ventilator system stable and accessible. The vibration isolation platform connects to the arm via a square joint interface.
CAD rendering of the KangaArm
Vibration measurements taken using Phyphox — a mobile accelerometer application — revealed the accessory box vibrates primarily at 21, 36, and 42 Hz, well above the device's operating frequency range of 4-11 Hz. The box was effectively a ringing enclosure, transmitting harmful vibration during normal handling.
My solution was a vibration isolation platform consisting of a 3D printed PETG top plate and an acrylic base plate connected by four vibration damping mounts. The design went through multiple iterations to achieve precise fit with the accessory box geometry. Vibration data was captured via Phyphox and processed through a custom MATLAB script to quantify attenuation across frequency ranges.
Result: 85% vibration attenuation across primary excitation frequencies.
Vibration- Isolation Plate Validation Test
To optimize the 3D printed PETG top plate, I tested four infill densities — 15%, 25%, 50%, and 60% — each assembled with the full damping mount configuration and measured using Phyphox accelerometer data processed through MATLAB. The objective was to identify the infill density that maximized vibration attenuation while maintaining structural integrity.
At lower infill densities, the plate lacked sufficient rigidity to support the accessory box and mounting hardware effectively. At 60% infill, the PETG lattice became dense enough to behave as a near-solid plate — rigidly coupling vibration through the structure rather than allowing the damping mounts to absorb it. 50% infill proved optimal: the internal lattice retained enough compliance to work in concert with the damping mounts, while providing adequate structural support for the system.
This systematic infill study across all four densities confirmed that plate density is a meaningful variable in vibration transmission — not just a print setting.
Vibration- Isolation Test Results
Vibration- Isolation Plate Validation Test Set-Up
CAD Rendering of the Vibration- Isolation Plate
Photo of the Vibration- Isolation Plate in Use
1st Top Plate Iteration
2nd Top Plate Iteration
3rd Top Plate Iteration
User feedback sessions were conducted with nurses and doctors at Jacobs Medical Center, evaluating ease of use and gathering design feedback to inform further iterations. Clinical input was integrated directly into the design refinement process.
Furthermore, I designed and built a dedicated project website documenting the full system, design process, and technical outcomes.
The full arm system was selected for patent consideration by the UC San Diego Technology Transfer Office.
For more details on the device and the user feedback sessions, please click here to view our full project site.
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