Tools:
User Testing, CAD, Ergonomic Assessments, Anthropometrics, Rendering, Rapid Prototyping
Timeline:
4 Weeks
Team:
Juliette Bechtolsheim, Anjali Surana
Project Overview
We redesigned the handle of a laryngoscope, a medical tool used for tracheal intubation, to improve its ergonomics, usability, and comfort for healthcare professionals. Our focus was on optimizing the handle geometry to accommodate diverse hand sizes and grip styles while reducing muscle strain during prolonged use.
Ergonomic Analysis
We began by analyzing the existing laryngoscope handle to understand how users interact with it during procedures. To do so, we visited the Stanford Medical Center and received a demo from a neonatal doctor. We also got to practice with the laryngoscope ourselves. Additionally, we watched video demos online and observed other doctors using the tool as well.
Developed a force diagram to visualize hand and thumb forces.
Identified discomfort from narrow width, awkward thumb placement, and unnecessary finger ridges.
Key Design Insights:
Eliminate finger ridges for universal hand fit
Widen handle diameter for improved grip comfort
Add thumb grooves for intuitive placement and control
Design Space Exploration
We generated 25+ concept sketches exploring handle profiles, groove orientations, and angles.
10 initial sketches explored geometric possibilities.
15 refined group sketches focused on ergonomic parameters like curvature and thumb alignment.
This iterative process helped narrow down the most comfortable and intuitive forms before prototyping. We also created a list of design parameters using anthropometrics to guide us in our prototyping process. Using the design parameters and our concept ideas, we created 15 foam prototypes.
User Testing
We conducted multiple rounds of user testing with multiple participants (Stanford Medicine doctors who use laryngoscopes regularly and with varying hand shapes and sizes) using foam prototypes. Participants held, rotated, and mimicked the motion of inserting a laryngoscope to assess:
Comfort
Grip stability
Intuitiveness
Test Method:
RULA evaluations
Hand and wrist surveys
Likert scales
Findings:
No finger ridges improved comfort across users
Slightly wider handle enhanced stability
Thumb grooves increased precision and ease of control
Users had varying grip preferences, so a neutral curvature was favored
Final Design
Key Features
Three thumb grooves for intuitive placement and stability
Smooth curved surface—comfortable for various grip styles
Slight angle in the top thumb groove for ergonomic alignment
Wider diameter and shorter handle for balance and control
Materials & Manufacturing
Foam prototypes were fabricated for ergonomic validation before CAD modeling. Final CAD renderings were developed individually using Fusion.
