An ergonomic stethoscope for doctors
KEY WORDS: Physical products, user testing, ergonomics
ROLE: Ergonomic Designer
CLASS: ME115B, Product Design Methods
TIMELINE: 3 weeks
TOOLS: Adobe Photoshop, CAD, Crafting Foam
UPDATING THE STETHOSCOPE
The Nova Stethoscope is part of a design challenge to develop an ergonomic stethoscope using traditional drafting methods.
The traditional metal stethoscope is a persistent, long-lived design. In 1853, George Cammann developed the first two-ear stethoscope for commercial production, and it has remained the standard design to this day.
Despite its enduring 150+ year history, the metal stethoscope design is not kind to the hand, requiring the user to perform regular repetitive actions, waving the stethoscope over a patient's chest, while keeping their wrist at an uncomfortable 90˚ angle.
In 2017 the US Bureau of Labor reported repetitive strain and sprain injuries were, once again, the most common workplace injures. Designing devices to reduce these repetitive motion injuries is a crucial step to support our medical professionals.
The Nova Stethoscope tackles this ergonomic issue by incorporating an electronic 4cm diameter by 7cm length sensor into a design that weds the iconic stethoscope visual to a more comfortable grip.
My visual studies of the Cammann "classic" stethoscope
How might we design a stethoscope for doctors that lessens the risk of a repetitive-motion strain injury?
After studying and drawing multiple classic stethoscope designs, I considered the different ways the doctor and patient interact with the stethoscope. By observing general practitioners using an electronic stethoscope on patients, I categorized these actions into:
Picking it up
Holding it to the patient's body
Checking if the device is on/off
Turning the device on/off
Based on these interaction requirements, I gathered relevant anthropometric data on the 5-95% percentile of human hand measurements. This data insures the dimensions of future prototypes will be suitable for the majority of the population.
Break down of physical interactions with stethoscope (2017)
Sketching and Ideation
Next I wanted to visualize a wide variety of potential design directions. The wilder, the better-- it is always possible to reign in an over-the-top design, but far more difficult to spice up a series of nearly identical safe choices.
In my initial exploration, I took inspiration from any objects that are made to be held for long periods of time: bike handles, video game consoles, spray bottles, garden hose handles, kitchen spoons, and more. What other objects work to keep the hand in a neutral, non-aggravating position?
Sample of 30+ sketch designs
Next I selected my two most likely prototypes and built them out of high density foam. Quickly shifting to low-fidelity physical prototyping helps me get immediate, low-cost feedback from users.
Galaxy Stethoscope, low fidelity model
Its round, door knob-like handle is easier to grip than a classic metal stethoscope while still bearing a resemblance to Cammann's original design. It is intuitive to pick up and use.
1. GALAXY STETHOSCOPE
The first prototype was built with the primary goal of resembling the classic, friendly look of a traditional stethoscope while also making the handle easier to grasp.
Round shape is "friendly," "familiar
Intuitive to pick up
Easy to grasp
Finger ridges are too shallow
Left an empty area behind it in the palm, should mould more to shape of hand
The handle beneath the sensor allows the user's wrist to remain in a neutral position whether pressing the stethoscope to a patient vertically or horizontally. It resembles the design of a spray bottle and is free-stranding.
Nova Stethoscope, low fidelity model
2. NOVA STETHOSCOPE
The second prototype was built solely with the goal of creating a neutral wrist position for the user.
The "most comfortable grip I've used yet"
Intuitive to use
Trigger rest fits multiple sizes of hand
Easy to hold
Bottom edge of the prototype could be softer, it digs into hand
The "gun" vibe feels uncomfortable to some users
The final "Nova" prototype prioritized a comfortable, neutral wrist position over the aesthetic callbacks to the original metal stethoscope.
Based on the feedback from users, the final model was slightly larger, given rounder edges at the base, and smoothed the trigger-finger rest. The base was broadened to make the stethoscopes's freestanding position more stable.
Nova Stethoscope, 2nd prototype
Next Steps and Reflection
Part of the challenge proposed in the original prompt asked me to design a stethoscope without the help of CAD tools. Although using traditional drafting methods was a useful exercise, in the future I'd like to create a fully realized model in Solidworks.
Function over form: prioritize a non-stressful neutral wrist position to avoid injury.
There's no single correct way to approach a design challenge. Exploring a wide variety of designs is useful before narrowing to just a few approaches.
Thinking visually is key: draw to think.
Designing an instrument from scratch was a great challenge. In the future, I'd like to do a similar anthropometrics study on VR and AR headsets and technology, another interest of mine.