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  • Writer's pictureShafiq x mēkā

Casing design for handheld devices

Updated: Dec 20, 2022

From the outside, designing a case seems easy. All you have to do is make sure the insides fit, make sure the outside looks good by choosing the right shape and colours. This could not be further from the truth. A lot of research goes into usage, ergonomics and trends amongst other things.

Using an example from our work with Astar Singapore, we take you through the process of designing a case for a handheld device to be used in healthcare.

Quick rundown:

  1. Design brief to set parameters

  2. Identify interaction points

  3. Research on similar products

  4. Research on trends

  5. Testing and improving for ergonomics

  6. Final render and CAD designs

  7. Final approval with physical prototype

  8. Manufacture

Design brief The most important thing to start of with is the client's specifications. This could cover everything from budget to specific colour requirements. This allows us to set the parameters with which to measure success.

In this case, success was measured by:

- Ease of use

- Comfort

- Future-forward design

As a handheld device, the weight of the device and duration of use per session were a big part of the consideration for ease of use and comfort. As we weren't involved in the electronics design, we also had to triple check the dimensions of the innards of the device. While it would be best if we were provided with a Computer-Aided Design of the innards, however in this case, we had to create our own CAD model of the innards.

Identify the interaction points In a situation where we would come in to create the enclosure only after the electronics gets assembled, we begin by determining the interaction points the device. Interaction points provide us with the limitations and reference for the final design. These points are set and cannot be changed. Such areas could be where the charging point are or the input and output of the electronic device are located. These areas would determine part of the design of the enclosure.

Looking closely at the current build of this device, there are three interaction points. Two of the points are cables - input and output, while the other interaction point would be the lens to be in contact with human skin.

Look for similar products and study its design As we knew the device would be used by medical professionals in their daily interactions, it was important to study current devices and their interaction. The intention is not to copy these devices but rather to take inspiration for our design. In this case, we have a unique form where the lens is at the bottom of the device. Similar devices are handheld ultrasound devices, handheld microscopes and skincare devices.

From here, we were informed of clear interaction cues. We observed that in these handheld device, the point of contact of the hand and the device is of a different material compared to the rest of the enclosure. On top of that, there are bumps and curves on where the device is held. This is mainly for the user to get a better grip of the device while in use.

Being inspired by trends There are a few key design considerations when designing a product that is within the consumer healthtech sector. With reference from the study of trends in this sector, it would influence the way we would design this enclosure. Its form and colours would lean towards using pale blush colours, white and light greys and soft rounded forms to portray a soothe feelings of serenity. The materials would be nature-inspired with pleasant colours such as earthy browns, oceanic blues and energising foliage greens. As this product would come in contact with the skin, soft textiles can be used to provide comfort. We then pull out words, images and other materials that would inspire all these design considerations that would assist us with the overall look and feel of the enclosure’s design.

Build quick prototypes With the CAD of the innards, we 3D printed a model to act as a skeleton for further refinement of our concept. At this point, we are trying to find ways for the user’s hands to comfortably hold on to the device. To do this we added plasticine on and around the 3D printed model to get a feel of various designs within a short time.

With the various parameters for the design of the enclosure, we are now ready to build prototypes to gather input from users.

Gaining feedback from client The client was the main user of the device and it was easy to bring down some samples and observe how he interacted with the different designs. We were keen to observe how intuitive and comfortable our designs were.

Some questions we asked/observed:

  1. Were any cables getting in the way?

  2. Was the client holding on to the device the way we designed it?

  3. Was there a more intuitive way of holding that they were led to?

In this case, we only had one user to get feedback from but it provided us with a wealth of information to improve further.

Improving on the design Back to CAD, but this time we have valuable feedback from the client. After several models made with plasticine, we were able to narrow down a basic form for the design. We used Autodesk Fusion 360 to create and 3D Print various forms that allowed us to add and remove parts as needed. In addition to form, this also allowed us to experiment with different materials.

CAD The final model was sculpted to create a smoother and easier to manipulate model.

A render was created for final approval.

The devil is in the details Now, moving on to the details of the enclosure.

We had to:

- Create a shell

- Make provisions to hold the innards of the device in place

- Make slots for the interaction points of the device - the lens and the cables

- Add in buttons - a power button and zoom controls

- Segment the enclosure to make assembly easy

A final 3d print is done to ensure all dimensions are accurate. This also provides the client with a physical model to interact with for final approval. After final approval, parts are sent out to be manufactured and finished according to specifications.

What we learnt - Designing for ergonomics - It's a process of testing and feedback. Rushing through this stage to make a decision will lead to subpar designs

- Reverse Engineering - Triple check ALL work to ensure a smooth transition through different stages

- CAD workflows - From Rhino or zBrush to Fusion 360, we need to improve on our workflow to improve efficiency.

This project was different compared to the other case designs we had done. It was an opportunity to challenge ourselves to learn more and improve on the value we provide to our clients. We clearly identified the design problems and created several concepts and ideas from it. We consulted, updated and even have the client to be part of the design process. We created the CAD model, printed it out, tested the fit and went on finishing it off with the right materials together with several suggestions that would provide a delightful experience for the end user.

Do you need help with design and engineering? mēkā is here to help. Drop us an email at Even if we can't help, we'll point you in the right direction.



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