Using a knife with a physical impairment
How might we reimagine the electric knife experience to empower users with physical limitations through inclusive design?
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Scope
Team
Timeline
(2 months)
Project overview
Background
Opportunity
Goal
This project was conducted for my Mechanical Engineering I class at Tufts University.
Reimagine the experience of using an electric knife for a persona with cerebral palsy.
Develop a prototype of an electric knife with an emphasis on inclusivity, accessibility, and safety for individuals with physical disabilities.
Objectives
- Understand pain points of existing users using the Proctor Silex electric knife
- Determine product design specifications
- Empathize with our end users, people with cerebral palsy
- Propose user needs and system requirements
- Develop a inclusive, accessible, and safe product design prototype
Format
- Phase 1: Evaluative research via product audit, secondary research, knowledge elicitation, and a product decomposition
- Phase 2: Generative research via literature review and market research
Key Findings & Insights
Evaluative Research
While the handle design is typical of other electric knives on the market, users expressed dissatisfaction with its bulky and heavy build.
The large and heavy handle causes discomfort and strain for existing users. This pain point is amplified for users with smaller hands, limited grip strength, or mobility impairments. The electric knife redesign should use anthropometric data to accommodate a wider range of users and fit beyond just the 5th to 95th percentile of adult hand dimensions for both men and women and minimize required grip force.
Users reported using the knife for both typical (e.g., food preparation) and off-nominal tasks (e.g., art projects, woodworking). Across all use cases, they experienced difficulty achieving clean cuts due to the blade’s excessive flexibility, which compromised precision and control.
Due to the nature of the blade's flexibility, this reduced overall satisfaction and limited the product’s perceived versatility and effectiveness. Our redesign must provide a more rigid blade option while balancing safety and control for users.
Generative Research
The redesigned product must enable users to cut food safely and effortlessly, while supporting user autonomy and independence throughout the experience.
Other products in the market address similar accessibility needs by integrating design solutions like right-angle handles, ergonomic form factors, and attachments tailored for wheelchair users. Through our research, the team identified a gap in the market for a more holistic, multi-functional solution that supports users with varying physical abilities.
Designing for our persona, Emily, who has ataxic cerebral palsy
Snapshot of our product redesign idea development
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Down selection of each of our ideas
Final prototype of our concept, inspired by an assistive chopping board and a paper guillotine
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Risk matrix of our product redesign
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Conclusion
Our product redesign enhances user safety and accessibility while balancing user autonomy. It is safer to use, requires less muscle control, and eliminates a trigger button, making operation simpler. However, the redesign has drawbacks, such as longer cutting times and limited functionality for tasks like carving. Overall, it is easy to operate, has a low risk of injury, and is easy to clean, which are all key elements for our end users and of accessible design.
Learnings
- Gained a deeper understanding of assistive technology and principles of accessible design.
- Acquired knowledge regarding technical methods within the design process such as problem statements, user personas, risk matrices, down selection, ideation techniques, and more.
- First time experiencing and gaining knowledge in the design process from preliminary ideas to prototyping for a physical product!
- Developed experience in collaborative teamwork and effectively delegated tasks by leveraging individual strengths and weaknesses.