CONTINUOUS GLUCOSE MONITOR (CGM) PROTECTOR
CAPSTONE PROJECT
Topics Covered, Semester 1: Ethnography, Human Subjects Testing, FDA Device Classification, Intended Use, Regulatory Pathways, US Regulation, FDA Guidance Documents, Use Cases, User Needs, EU Regulation, Standards, Initial Hazard Analysis, FMEA, FTA, Risk Summary, Product Design Specification, Verification & Validation Planning, Design Traceability, Electronic Quality Management Systems.
Topics Covered, Semester 2: DMR, DHR, V&V Protocols/Testing/Reports, DOX, Intellectual Property - Patentability and Infringement, Animal Testing, Human Clinical Testing, EU MDR, FDA Third Party Review, FDA Pre-Submission, FDA Post-Market Surveillance
Course Description: This class is a year-long capstone course dedicated to fabricating a solution to an unmet clinical need and formulating the appropriate regulatory documents and information to theoretically undergo FDA approval. With an assigned team, students are tasked with creating professional documentation and prototypes that meet the industry standard.
Our Project: Upon the completion of several weeks' worth of ethnographic research, our team selected a project topic that was near and dear to our hearts: protection of the CGM site on type 1 diabetic athletes during contact sports. One of our team members struggled with this issue growing up, which created a strong personal connection to this topic for all of us.
Unmet Clinical Need:
Design a protective device for athletes that prevents the DEXCOM G6 CGM from being damaged or lost during contact sports.
Our Solution:
Continuous Glucose Monitor (CGM) Protector
Features: Stretchy spandex sleeve, Adjustable Velcro straps, Silicone protector, Holes in silicone for breathability and signal transmission, Interior pocket to house silicone protector
Click images to expand and explore
For more background information on our project, please click HERE to watch an informative video summary.
PERSONAL CONTRIBUTIONS
Throughout the first semester, I played a key role in the fabrication and creation of our team's physical device. In unison with Fabrication Lead Hannah Parks, I collaboratively worked as Fabrication Assistant, contributing significantly to rapid, low-resolution prototyping, high-resolution prototyping, and ultimately design-freeze.
During the second semester, as appointed IRB Lead, I was tasked with creating a human-subject testing protocol (with myself as the Primary Investigator), and consequently in charge of Validation, taking the lead on formation of these testing procedures and resource outreach. I am the primary point of contact with our faculty mentor, Dr. April Chambers, and with the University of Pittsburgh IRB, amongst other resources.
FABRICATION
SILICONE MOLDING:
A major component of our project was designing a working prototype to solve our unmet clinical need. Consequently, silicone was an optimal material to create a shock-absorbant and flexible protective covering.
Silicone Components:
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Smooth-On Ecoflex 00-30 Silicone
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Smooth-On Dragon Skin
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Smooth-On Slacker Additive
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Smooth-On Thi-Vex Silicone Thickener Additive
Watch the videos below to see me perform several key steps in the silicone molding process:
SEWING:
Another component of our design, though still being tested, is the inclusion of an elastic band to help secure the silicone protector in place. If we proceed with the addition of an elastic band, there are several design inputs that will be key to include.
Elastic Band Necessities:
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Adjustability
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Breathability
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Stationary
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"Grippy" material
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Removable
This early iteration prototype addresses the need for adjustability by including an adjustable velcro strap. The material used is a spandex material, allowing for breathability. Unfortunately, this prototype has yet to prove its efficacy at staying stationary on a human arm. Implementing a material "grippy" properties will help maintain a stationary position.
 Spandex material pinned in place prior to sewing |  Close up: note the multiple Velcro attachments for adjustability |  Adjustable Velcro allows for a snug fit in order to keep the silicone protector stationary |
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TESTING
"KILLER" EXPERIMENTS:
During an iterative design process, it is important to quickly verify whether a design concept is viable to proceed with or not. To determine viability of our rapid prototypes, I formulated a basic procedure that would allow for relatively equal shear impact on each prototype design. The key factors being testing with these killer experiments are shape and material.
Procedure:
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Place 3D printed mock DEXCOM G6 on cardboard surface using medical adhesive tape.
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Directly above and in-line with the CGM, mark the weight drop-point with sharpie to ensure consistency.
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Hannah and I arbitrarily selected a 32 cm drop-point.
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Use a consistent weight to replicate an identical shear force during each trial
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Determine the weight necessary for this experiment by seeing the minimum weight that will detach the DEXCOM.
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We created a box made of foam core and filled it with marbles until we reached an appropriate weight.
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Place prototype over DEXCOM. Drop weighted box from drop-point and video the results. Complete three trials.
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Repeat step 4 for all prototypes.
Sketch of procedure
Steps 1 & 2
Steps 3, 4, & 5
IRB SUBMISSION | PRIMARY INVESTIGATOR OF STUDY
Human Subject Testing:
As the PI, it was my responsibility to create a protocol for the human-subject usability testing that we wanted to complete for the Validation portion of our V&V. I have worked tirelessly on our IRB submission, using resources such as our IRB representative, our faculty mentor, and other Pitt BioE faculty.
Due to the limited timeline of our Capstone course, we only made it approximately halfway through the IRB approval process prior to the end of the school year. Our study qualified for expedited IRB review due to the low risk level. Our documents would require several edits were we able to continue with the study; Attached below are the latest versions of each document.
Click here to access revision 1 of the usability protocol document:
Click here to access revision 1 of our informed consent form:
Click here to access revision 1 of the Qualtrics usability questionnaire intended to be answered by the participant after completing the research activites:
Click here to access a concatenated participant outreach pdf. This file includes the recruitment poster, recruitment email, verbal recruitment script, and the Qualtrics version of the informed consent document.
VALIDATION
Protocol:
Due to my leadership as PI for our IRB submission, I was also in charge of conducting validation on our product. Validation testing ensures that the user's requirements are met, whereas verification ensures that the engineering/designer requirements are satisfactory.
As mentioned above, since our IRB submission was not approved in time, we had to alter our protocol last minute to receive some results. Instead of our intended full usability study, we surveyed a focus group of collegiate diabetic athletes (part of the DexcomU program) to receive their input. Though this alternative validation method was not 'ideal,' we still received useful information from the survey, setting a clear path for any potential future improvements.
Click here to access revision 1 of the usability and comfort validation protocol:
Click here to access the validation test report: