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MIELA EFRAIM
EpiPen 2.0
Redesigning the EpiPen to prevent accidental injections
Defining the Problem
From 1994 to 2007 there were over 15,000 unintentional EpiPen injections, including many cases from trained healthcare professionals. The problem of accidental injections stems from the lack of a match between the system and the real world. Natural mapping, when the relationship between a product's controls and its functions follows real-world conventions, is violated in the EpiPen's design. Contrary to the real-world assumption that safety guards directly protect the hazardous element, the EpiPen safety cap is located at the opposite end the needle.
This mental model, based on the assumption that the blue safety cap covers the needle end, leads to accidental injections. Users mistake the blue safety cap to be covering the needle and assume the press button is at the other end, thus accidentally pressing on the needle and injecting a dose of epinephrine into their finger.
Correct demonstration of how to self-administer
Examples of safety guards directly protecting the hazardous element (natural mapping)
Demonstration of accidental injection
Heuristic Evaluation
Based on Nielsen Norman 10 Usability Heuristics. I found error prevention and lack of match between the system and the real world to be the highest priority usability issues. The current design fails at error prevention because the location of the safety cap and needle being located at opposite ends lends itself to a common user error. The lack of a match between the system and the real world is evident in how the design does not follow the user's mental model of how to operate a ballpoint pen or other real-world conventions. Lack of visibility of system status, caused by no indication of the progress of the injection, and lack of consistency and standards rank as medium priority usability issues.
Known Problems Analysis
Based on MDRs (medical device reports) to the MAUDE (Manufacturer and User Facility Device Experience) Database and FAERS (FDA's Adverse Reporting System) Public Dashboard. While the bulk of reports were related to device malfunctions and issues with the epinephrine liquid, I focused on the reports related to usability to inform my research.
Participant Profiles
For this project, I worked with 3 research subjects who participated in user interviews and task analysis. Considering key stakeholders for this project, I made sure to find research subjects who each represented a core user group (prescribed EpiPen user, family/friend of EpiPen user, healthcare professional) in order to cover a range of perspectives and experiences.
User Interviews
Based on responses from structured interviews with each participant to gauge attitudes, perceptions, and previous experiences related to EpiPen. Key findings include reported fear surrounding the injection, a lack of intuitive design, and not knowing if the injection was successful.
Task Analysis
Conducting separate rounds of observational task analysis with each research subject. After conducting pre-task interviews, I asked each research subject to administer an EpiPen to another person. Subjects used a training EpiPen, which does not have a needle but has instructions printed on the label, and I did not provide any training or further information. Before the task analysis, I created a risk analysis matrix where I predicted the highest likelihood potential use errors to be faulty hand placement, accidental injection, and keeping the needle injected for too long or too short. To document the task analysis, I filled out an observational task checklist and found that Participant #3 (a healthcare professional who completed formal EpiPen training and has previous administered an EpiPen) committed the fewest user errors. To investigate the cause of the user errors committed by all participants during the task analysis, I conducted root cause analysis using the 5 Whys method and found that the mental model of the user failing to match how the system actually works to be the most common root cause.
Hierarchical Task Flow Diagram - Intended Use
Risk Analysis Matrix
Observational Task Checklist
Root Cause Analysis - 5 Whys
User Needs + Design Requirements
Identifying universal user needs encompassing each user group and translated them into design requirements to inform the design process for the new EpiPen concept.
I reviewed ISO 11608-1:2022, a testing standard for needle-based injection systems, to further inform the design requirements.
Form Exploration
Design #1
For the first iteration, I chose a simple design similar in shape to the original EpiPen but more closely resembling a ballpoint pen. The press button is located at the top and the needle cover at the bottom, making it easy and intuitive to distinguish between each end and recognize the functionality. There is a plastic safety seal located above the needle cover that must be peeled off in order to activate the device. Once the injection is complete, the status toggle changes from green to red to let the user know that the injection is finished. To create a first prototype, I 3D printed the body, needle cover, and press button and used internal components from a ballpoint pen to make it functional.
User Testing (Design #1)
For the first round of user testing, I held individual 20-minute in-person testing sessions with 4 participants (1 prescribed EpiPen user, 2 family/friends of prescribed EpiPen users, and 1 healthcare professional). I asked structured post-interview questions to gather feedback, and administered a questionnaire closely based on the System Usability Scale (SUS) to evaluate the prototype.
Design Evaluation - Modeled after System Usability Scale
Design #2
For the second iteration, I changed the design based on feedback from user testing. I added a progress indicator with 3 states (start, in progress, ready) to replace the color-changing toggle which was confusing for users. Continuous feedback during the injection will reduce anxiety and give the user increased confidence that they are performing the injection correctly. I also added a lock ring to replace the safety seal for integrated needle safety.
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