A2: Immersion Blender Model Prototype

This past week, we focused on model prototyping in HCDE 451. In class, we completed an activity aimed at redesigning an EcoATM used for recycling electronic devices, including smartphones and mp3 players. Through this exercise, I was able to learn how to creatively use the materials around me to create prototypes that go beyond a simple screen interface. By testing this prototype with users, my activity group learned how people interacted with our system from beginning to end and made design adjustments accordingly.


I used what I learned from this exercise in redesigning a handheld immersion blender for assignment 2. For this assignment, I wanted to incorporate the principles of universal design, or “the design of products usable by as many people as possible” according to the brand OXO.

The process started with research on how handheld immersion blenders work. In all honesty, I’ve never used one before, which gave me a unique perspective in tackling this challenge because I didn’t have preconceptions to begin with. At the same time, it also made brainstorming designs difficult since I didn’t know what people enjoyed/disliked about the existing handheld blenders on the market. To gain insight on this, I read Amazon reviews online to see ratings and comments on blenders from various brands. I also did some research on universal design to get a better idea of how to design for a broad spectrum of people. This website by the Center of Universal Design provided information on seven universal design principles developed in 1997 by North Carolina State University that I will refer to later on in this post.

Based on the information from research on blenders and universal design, I created many sketches of ideas on how this blender might function:

As you can see from the sketches above, I had considered several options for controls. One option was to have physical buttons for +/- to change speed and a screen in between to give a readout on speed and consistency. Another option was to use a twisting knob at the top of the blender to control speed and have the screen on the top. A variation of this design was to have the knob move up and down to turn on and off. And lastly, I considered putting a dial on the side that could be twisted to change the speed with the screen on top. I also played around with the idea of having “arms” that could attach to the side of the bowl and allow for hands-free blending. For all of these designs, I knew that I wanted the blade to be able to eject to allow for easy cleaning because that was a feature people enjoyed in existing handheld blenders. I also knew that I wanted the blade depth to be adjustable because flexibility in use is one of the universal design principles I discovered in my research. By allowing the blade depth to adjust, the design accommodates for different bowl/cup/pot/etc. depths, but also different preferences users might have.


At the end of all the sketching, I got feedback from peers on the designs I had come up with. Based on this feedback, I decided to roughly prototype the design with the twistable knob at the end to adjust speed. This was the design that would allow users to have a greater area to hold the blender, which is important because of the universal design principle of appropriate size/space for approach and use. The prototype was created with paper, rocks (for weight), and tape.

From the usability testing I conducted with this draft prototype with two participants, I learned that the knob was actually difficult for both users to manipulate with only one hand. Since I had written the speed numbers on the side of the prototype, I also noticed the participants’ grips sometimes covered them up, which was not user-friendly because then they would have to change their grip to know what how much to turn the knob. Participants also suggested having the device power on/off in a different way since the knob could get unintentionally twisted and turn on by accident. These are all considerations I made moving onto the next step — the final prototype.

In creating the final prototype, I decided to make a few changes. Instead of a knob, I switched to a slider. I figured that the slider could accommodate for both left/right handed people and give people with smaller hands something to grip onto on the device. It is also manipulable with only one hand if the user so chooses, which is consistent with the universal design principle of low physical effort since another hand isn’t needed. The screen on this prototype is a touch screen, which powers the device on and off more deliberately than the knob in the previous prototype. Additionally, I attempted to create a separate “holder” for the appliance so users could have hands-free blending.

In this iteration, I also got more creative with materials. The body of the prototype is created with part of a skinny plastic bottle I found while wandering a store. The bottom of the prototype was stuffed with rocks to simulate a motor and then stuffed with newspapers to hold them in place. I also decided to try papier mache and a mix of different types of papers in the prototype to give structure to the design.

Here are pictures of the final prototype and screens:

The touch screen is at the top of the blender and indicates what mode the blender is in, the speed of the blender, and the consistency of the blender. If the blender is in speed mode, the touch screen has a button to control if the blender is on/off. Speed is indicated by a number and consistency is indicated with words. If the blender is in depth mode, the touch screen has a button to control ejecting the blade. If the blender is switched on, depth mode is deactivated for safety.
The mode button allows the user to toggle between speed mode and depth mode. The slider adjusts the speed or depth depending on the mode the blender is set on, which is indicated by the touch screen at the top of the appliance.
This is the “holder” that allows for hands-free blending. It is laid across the edge of the cup/bowl/pot/etc. and the blender is put through the hole. This keeps the blender upright while blending happens. Ideally, I would’ve liked this to be transparent so that users can see through it while they’re blending.

The usability test for this prototype is documented in the following video:


From the usability test conducted and the critique session in class, I learned a lot about my prototype and the video and how they both could be improved.

  • The usability study participant was confused about how many times to push the mode button to get to the mode he wanted. I think that rewording the first screen to something along the lines of “Use the mode button to toggle between speed mode and depth mode.” would’ve helped him understand that there are only two modes, so pushing the button will just switch it to the other mode.
  • The participant used two hands on the device, even though my intention was for it to be easily used by one. He said that with more familiarity of the appliance, he would be more comfortable using it with one hand. It would be interesting to study this further to see if there is a way to make it so that even on the first use, users only feel the need to use one hand to control the blender.
  • The user liked being able to change the blade depth of the immersion blender and had never seen that feature before. He mentioned that this feature would help with comfort when blending.
  • In class, I realized that music can detract from what is going on in the video. It also would’ve been great incorporate the users’ feedback in the video. I will definitely keep these points in mind for future videos that I make.
  • I wish I would’ve played around more with form. Through later research, I learned that cups are quite difficult for people with arthritis to hold and my blender requires the user to hold it like they do a cup. Although there is the slider and a ridge above the slider for easier gripping, I think it would have been interesting to play around more with this aspect of the design.

Overall, I had a great experience prototyping a handheld immersion blender despite never using one before and learned a lot that I’ll be able to use for the next project — a 2.5D prototype!

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