AeroSafe
My Engineering Senior Design team and I designed AeroSafe, an active intubation barrier that would monitor the risk of infection and effectively reduce the quantity of SARS-CoV-2 airborne particles released during intubation procedures. After multiple design iterations, reviews, reports, and presentations, our team manufactured a working prototype of AeroSafe.
Needs Statement
Approximately 43% of the patients hospitalized for COVID-19 need to be intubated. Current intubation barriers were proven to be ineffective and inconsistent. This results in an increase transmission of COVID-19 to healthcare workers (HCWs).
Problem Statement
There is a need for an assistive device that can monitor the risk of infection and effectively reduce the quantity of SARS-CoV-2 airborne particles released to the environment before, during, and after tracheal intubations in order to decrease the risk of disease transmission to HCWs.
User Needs
Disposable
Easy to Use
Safe to Use
Easy to Set-up
Portable
Inexpensive
Objective
Throughout the design process, my team and I referred to the user needs to design AeroSafe. After thorough research of intubation barriers currently on the market, we defined our objective to design a device using negative pressure to create a sealed environment with a way to collect and process data to display to the user. With these features, the user would know when negative pressure has been established in the barrier and if particle leakage is occurring during the procedure.
Design Solution
To meet the user needs requirements, our team designed a three component intubation barrier consisting of a rigid base, a skeleton and tent, and a feedback alert system. The foldable barrier uses a hospital vacuum system to seal the patient in a negative pressure environment to prevent infectious airborne particles from infecting healthcare workers. A pressure sensor would be used to collect and process data to notify HCWs when the viral particle count is above or below a safety threshold. For the following demonstrations, the tan body will represent the patient and the blue body will represent the healthcare worker.
Base
Base
The portable, rigid base provides a structure to attach the skeleton and tent. The reusable base rests on the patient’s bed during the procedure and surrounds their head and neck with the U-shaped design.
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The base has vacuum and oxygen port seals on each side to seal the hospital vacuum and oxygen tube to create the negative pressure environment and provide oxygen to the patient. The clamps on top of the base are used to attach the skeleton, the velcro on each side of the base secures the plastic tent, and lastly the side drawer holds the feedback alert system components.
Skeleton and Tent
Feedback Alert System
Velcro
Clamps
Base
Base Components
Skeleton and Tent
Hand
Slits
Skeleton and Tent Components
Fold Up
Fold Down
The disposable skeleton folds up and down using hinges and adjustable hinge locks. The plastic tent seals the internal environment by attaching to the base with velcro. The tent also has hand slits to allow the healthcare workers to perform the intubation.
Feedback Alert System
Feedback Alert System
Components
Internal
Sensor
Light
Power
Switch
Speaker
External
Sensor
External
Environment
Internal
Environment
Device Environments
The feedback alert system is used to improve the efficiency of the intubation barrier by measuring the device’s effectiveness. It detects particle leakage by measuring the air pressure of the internal and external environments. If the differential pressure of the internal and external environments passes a safety threshold, a light and speaker will alert the healthcare workers and prompt them to check potential areas of leakage in the device.
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The particle sensors provided to us by the Simulation Center at UC Davis Health were formaldehyde aerosol counters. The safety threshold for formaldehyde aerosol leakage is 80 ug/m^3 reading. Since the infectious dose of covid-19 isn’t known, we chose to reduce this safety range to 40ug/m^3 just to be safe.
Materials and Manufacturing
In order to ensure the device is durable and cost efficient, our team picked the following materials to manufacture AeroSafe. Acrylic was chosen for the base because of its high tensile strength and durability. These properties made it great for carrying the load and supporting the structure of the skeleton and tent. The hinges and hinge locks had to be strong enough to support the weight of the skeleton and tent and needed to be resistant to fatigue to allow the device to fold up and down. Delrin and PLA met all of these requirements making them the best materials for the hinges and hinge locks.
Base
Acrylic Sheets
Laser cutting
Electronic Box
Acrylic Sheets
Laser cutting
Hinge Lock
PLA
FDM printing
Port Seals
Hinges
Delrin
Laser cutting
UMA 90
Polyjet printing
Prototype Set-up
Attach the skeleton to the base and adjust the height of the skeleton
Secure the skeleton by locking the hinge locks in the appropriate position
Drape the plastic tent over the skeleton and base
Secure the tent by attaching the velcro to the base
Tuck the remaining tent under the base to seal all potential leaks
Fold the skeleton and tent down after the procedure
Prototype Demonstration
Verification Testing
Vacuum
Breath Valve Mask
Nebulizer
Particle Counter
The first verification test performed was the particle clearance time, or the additional time required to clear out the majority of the SARS-CoV-2 particles that have been expelled into the internal environment. The hospital wall vacuum system, pictured on the left, can be adjusted to suction air out of the internal environment at a given pressure, ranging from 0-300 millimeters of mercury.
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For the experimental setup, a nebulizer filled with a saline solution was attached to a bag valve mask (BVM) and placed inside the barrier. The BVM had an air input of 8 liters per minute, and was squeezed 3 times in 20 second increments, to simulate a 1 minute aerosol generating procedure. At the same time, the device was hooked up to the hospital wall vacuum system to suck out aerosolized particles being produced. Three particle concentrations were placed in three different locations; inside the protective barrier, at the head, and at the foot of the hospital bed. Data was collected for a total of 10 minutes at various vacuum rates to determine the approximate clearance time.
Verification Results
Graph A
Graph C
Graph B
AeroSafe's particle clearance time was tested at different vacuum pressures, 160mmHg, 200mmHg, 240 mmHg, and 320 mmHg, labeled to your left as graph A, B, C, and D respectively. The horizontal green line represents our safety threshold at 40 ug/m^3. The blue line represents the internal environment and the yellow line represents the external environment.
AeroSafe performed the best with a higher negative pressure value of 320mmHg, AeroSafe was able to pass the particle threshold just under 7 minutes. However, if using two vacuums at 200mmHg, the overall pressure would be 400mmHg and AeroSafe would yield a post-procedural particle clearance time between 5.5 to 6 minutes.
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Graph D
Validation Testing
In order to perform validation testing for AeroSafe, we tested the performance of the our device using a passive acrylic intubation barrier as the gold standard similar to barriers on the market. We intended to test the gold standard device and AeroSafe and record the particle counters in the same three locations over the span of three simulated coughs. We planned to compare the data of AeroSafe and the gold standard to determine the performance of our device. Unfortunately, the Simulation Center's wall vacuum was under maintenance and we were unable to perform the validation testing accurately.
Acrylic Passive Intubation Barrier
Validation Test Demonstration
Intubation Demonstration
Packaging and Labeling
Our team had the opportunity to collaborate with a creative design team to develop the packing and labeling designs of our device. We designed the inner and outer packaging pieces through CAD (shown in the report) and provided all the information and instructions to include on the packages. By discussing our vision as a team and relaying those ideas to the design team, we agreed on the following packaging and labeling designs of AeroSafe.
Unit Level
Inner-pack Level
Case Level
Front Side of the Base & Electronic Box Package
Front Side of the Skeleton Package
contains the AeroSafe logo and images of the Base and Electronic Box
contains the AeroSafe logo and an image of the Skeleton
Back Side of the Base & Electronic Box Package
Back Side of the Skeleton Package
contains a message to the customer, manufacturing information, and cautionary guidelines
contains a message to the customer, manufacturing information, and cautionary guidelines
Exploded View of the Base & Electronic Box Package
Exploded View of the Skeleton Package
AeroSafe Instructions
Project Overview
This project was the most exciting part of my undergraduate career. I had the opportunity to work with a team of engineers and work cross functionally with design mentors, professors, and creative design teams. This experience allowed me to understand the engineering design process and the many roles within a project such as R&D, design, manufacturing, and product management. Overall this was an amazing learning experience!
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If you would like to see more details about the project and AeroSafe, please check out the following links.
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