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Amy Roberts

Amy Roberts is a product designer currently based in Austin, TX.

Published March 10, 2016

Model Prototype: Handheld Immersion Blender


OXO is a brand that is known for applying universal design to their cooking and food products, emphasizing good design, comfort, and ease of use. I was challenged to create a prototype of a handheld immersion blender incorporating these concepts, including features for variable speed control and a digital display showing level of viscosity.

I began by first doing some research on OXO’s products and their existing immersion blender. I also looked at the designs of other immersion blenders on the market and watched some Youtube videos to see how they are used.

Based on my research, I made several sketches, changing the grip forms, button placement, and button functions. From these, I chose three to prototype.

In order for the immersion blender to be used both left-handed and right-handed, I made all of my designs symmetrical. For my first design, I chose to create something similar to OXO’s existing immersion blender, keeping a simple two button format and adding the digital display to the top.

For my second design, I tilted the display, making it easier for people of varying heights to see. I also added a raised section above the hand so the user could rest.

In my last design, I wanted to explore different interactions. Many of the immersion blenders I saw had only two speeds and to control it you have to hold down a button. A better solution aligning more with Universal design would be to enable someone to operate the blender without holding the button, so it would be easier to use for people with weak grips. I decided to place an on/off button at the back and a button for changing speed near the digital display.

Screenshot 2016-03-09 15.41.35


First Prototype

My first prototype was very simple. I started with a dowel rod and taped a cardboard tube around it, stuffing newsprint inside of it to make it sturdy. I sealed off the top and added another piece of cardboard to represent a digital screen.

I wanted to keep the interface simple, so I created something similar to what I saw in other models. I added two buttons on the back of the blender that naturally fit within a person’s grip, one for a slower speed and one for a faster speed. The blender would only function when one of the buttons is pressed down.

Because it was difficult to tell where the buttons were when holding the model, I added two sections of folded newspaper to simulate raised buttons.

Screenshot 2016-03-09 15.42.40

Second Prototype

I constructed my second prototype in the same way as the first, with two key differences. I added a slanted area to the top so that it would be easier to view the digital display while gripping the blender. I also added a raised section above the gripping area so it wouldn’t slide out of the hand so easily. This would allow the user to take breaks from pressing the buttons while still holding the blender.

To make it easier to find the controls on the back, I used real buttons. The slight indentation in the buttons also allows for a better grip.

Screenshot 2016-03-09 15.42.52

Third Prototype

In my final prototype, I wanted to explore different controls. A blender with an on and off switch would reduce fatigue for the user and allow them to seamlessly adjust speeds.

Because I felt it was most important to have the on and off button within easy reach, I kept that button on the back of the prototype. I added a button to alternate through various speeds, and it seemed intuitive to place it at the top near the screen. However, this presented a problem: it was difficult to grip the blender while pressing the button to change speeds.

I solved this by folding newspaper to create a grip. This resulted in a form that was much easier to hold in the hand, freeing up the thumb to press the button at the top.

Screenshot 2016-03-09 15.43.03


I conducted a user test to evaluate four areas of my designs: Comfort, Ease of use, Ease of access to controls, and Satisfaction of experience. For the test, I created a simple potato soup recipe for the user to follow that involved changing speeds and checking consistency. This provided some context for the testing, since people who are using a blender might be preoccupied by a recipe.

Before beginning each prototype test, I briefly showed the user how to hold the blender and what the functions of the buttons were. I encouraged her to voice her thoughts so I could see what worked and what didn’t. At the end of the testing, I asked her to fill out an evaluation of each prototype, rating different areas from 1 to 5.

The first prototype was the most difficult for the user to use because it lacked adequate grip support. The display on the top was also hard for her to see without tilting the blender. During part of the recipe involving blending potatoes, she mentioned that it would be tiring to hold down a button for very long to blend.

It was significantly easier for the user to hold the second prototype due to the thicker area above the grip, but it still wasn’t very comfortable. The user thought that the tilted display was a big improvement and much easier to view.

The third prototype was the strongest. The user liked the way the grip fit in the palm of her hand and could easily reach the speed button with her thumb. She mentioned that having the power button near her fingertips was useful but also possibly problematic; if she needed to grip more firmly she might accidentally turn it off. Despite this, she was most satisfied with the experience of using this prototype.

Screenshot 2016-03-09 15.43.21