Senior Design Project:

Introduction:

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ALS is a progressive, fatal neuromuscular disease that leads to paralysis of muscles and loss of ability to swallow, speak, and breathe. One of the most debilitating symptoms is that of head-drop syndrome, in which weakened neck extensor muscles can no longer support the weight of the head, resulting in a chin-on-chest stature. This posture can cause discomfort, pain, and difficulty communicating. Existing head support orthotics restrict the anterior neck, hindering normal breathing and swallowing patterns. Our device attempts to address this unmet need. It is to be worn 16 hours a day, every day, by ALS patients, who are typically 40 to 70 years old. As seen in the figure, the device is a snugly fitting vest with front velcro closure and a padded neck support in the rear. A padded headband with a strap extending from the rear is secured on the patient's head, the strap is pulled tightly over the back of the next support (pulling the patient's head up and back into a neutral position), and is attached to the back of the vest by velcro to hold the head in place. 

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Description of Device Components:

1. Neoprene Vest with Velcro Closure

   • The vest is constructed with a dual layer of thin neoprene over porous foam textile. This is to ensure a moisture-wicking/cleanable surface to prevent sweat build-up. Overlapping velcro panels provide closure in the front and are designed to satisfy a wide range of body sizes.

2. Adjustable Belt Strap

   • An ​adjustable nylon belt, fastened via a plastic delrin clip, keeps the vest from riding up the patient's body. The belt is placed in the lining of the vest along the patient's back, and each end comes out of slits on the sides approximately above the patient's hip bones. 

3. Padded Headband

   • The padded headband is made with the same porous foam textile used in the vest and is filled with cotton fiber to provide comfort and breathability. It has an adjustable velcro strap in the rear to accommodate a range of head sizes. 

4. Rigid Neck Support Panel with Cushion

   • Serving as the pivot point for the head support strap, the neck support panel requires a rigid structural base coupled with a memory foam insert to provide cushioning. The rigid panel is 3D-printed out of polylactic acid (PLA) and is designed with a point of attachment to another rigid panel that drapes over the patient's shoulders and is sewn into the body of the vest. The back of the neck support is also covered in velcro to help secure the support strap. 

5. Velcro Support Strap

   • A simple nylon strap covered in velcro is looped around the back of the forehead strap and extends as far down the back of the neck support and vest as needed to correct the angle of the patient's head. 

6. Velcro-covered Back Panel

   • To ensure versatility of strap position, the entire back of the vest is covered in velcro so that support can be graded both throughout the day and as a patient's condition progresses. 

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Personal Contributions to the Project:

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Design Inputs and Prototyping

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While each member of our team has actively participated and contributed to each step of the design process so far, there are aspects of both the documentation and prototyping efforts where we each took charge. In terms of documentation, I was largely responsible for ethnographic data recording and consolidation. I was also primarily responsible for translating the ethnographic data into qualitative product design specifications and selecting the appropriate materials for prototypes beyond the minimum viable prototype (MVP). Then, as we began to formulate our higher resolution prototypes (iterations two and three), I took over fabrication. Iteration two began as a group effort of gluing the major components together,  following which I sewed the rest of the pieces. This was a quick job that included hemming the back panel edges, attaching velcro to the back panel and straps, and creating a padded headband with a removable strap. Iteration three became much more comprehensive, since we now needed a prototype with materials that are or closely mimic those intended for the final design, and it had to be structurally accurate to our most recent design. In general, I followed this workflow:

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1. Confirmed design intentions and component dimensions with team 

2. Selected and acquired additional materials that became necessary with design changes

3. Fabricated device:

   1. Cut the memory foam insert to shape and sewed it into a fabric casing (with velcro closure) to be placed over the rigid component of the neck support

   2. Created a pattern for the vest and cut out the fabric for that and the padded headband

   3. Sewed the body of the vest together, tailored the length, hemmed all edges, and left openings for adjustable belt and rear neck support panel to be inserted in the lining

   4. Sewed velcro to both the front closure and (almost) the entire surface area of the back panel of the vest

   5. Measured for and sewed a detachable velcro panel to secure the rigid neck support within the lining of the vest

   6. Sewed adjustable belt and velcro-covered support strap

 

The third iteration was presented at the Design Expo and again to our consulting physical therapist, Kathleen Brandfass from UPMC, for feedback. 

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Verification and Validation

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For design verification, I was responsible for devising two protocols and writing their accompanying reports. The first verification test was to assess breathability of the device's double-layer textile, as this traces back to a required material specification in the design inputs and ensures the patient will not overheat or perspire excessively while wearing the device. In addition to authorship I also carried out the test, in which three petri dishes were filled with distilled water and covered with a swatch of the double-layer textile. Initial mass measurements of the dishes were taken, and then measurements were made every hour for a period of 12 hours. Once all measurements were taken, the average vapor movement rate was calculated across the three dishes and compared to the acceptance criteria. The calculated vapor movement rate fell below the accepted value, therefore the device was not validated for this user need and alterations in material must be made to address the discrepancy. The second verification protocol I authored was a test to assess how much pressure the device exerts on the patient's chin and anterior neck. This was another design input designed to ensure the device was more comfortable and less restrictive than current technology. The test was to be carried out with a mannequin, with pressure sensors present on the areas of interest that would record the pressure before the device was put on and while the device was on the mannequin. The change in pressure would be calculated and compared to the success criteria. However, due to the nature of the design, the device does not actually come into contact with the chin or anterior neck, therefore it would not exert any pressure and the test was deemed unnecessary.

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In terms of validation, I was responsible for authoring a protocol and report for the required user need of adjustability. This user need ensures that the device can appropriately address varying levels of muscle control in the patient. The protocol called for a healthy subject to wear the device for a short duration with varying added weights to the forehead strap (which would simulate minor, intermediate, and major loss of muscle control). The subject would then rate how supported they felt at each level. This test was scheduled to occur in April 2020, but due to the circumstances surrounding the COVID-19 pandemic, all in-person validation efforts had to be postponed indefinitely. As a result, our team had to devise a plan to carry out alternative validation. We agreed we would distribute a web-based survey in which the participant would be asked to watch a brief video (found here) describing the device and then answer the accompanying questions that correspond to each required user need for the device. I was responsible for making the video, devising the survey, authoring the protocol, and authoring the test report with the results. 

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Next Steps for the Device:

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Another iteration of the device would need to be fabricated that addresses discrepancies in V&V testing. Specifically, alternate material selections would need to be made to verify the device for breathability, and the design and/or instructional materials would need to be altered to validate for ease of use. Ideally, future V&V efforts would incorporate the original protocols that were unable to be carried out and would yield passing results.