At Fusion Design we have done large projects like the airport scanner and the spherical radiosurgery device, but we have also done small designs such as a wearable ear-mounted camera.
Although small, it is complex. It has flex circuits, rigid and semi-rigid bending elements, over molding, five circuit boards, camera, LEDs, right/left ear mounting, Bluetooth, switches and batteries.
The function of this device is quite interesting involving video capture at the point of interest as well as cloud based connectivity through a mobile phone. The mobile phone is also the view finder for the ear mounted camera. If you see / record an event you want to keep, a simple push of a button will upload it to the cloud community where you can share with others.
Development of this type of product is done following our standard process. The client is heavily involved at least every week if not more often. This insures that the pre-existing product knowledge and the requirements of the final product are aligned throughout the process.
Background Research - We start by defining / understanding the key components required for this device work mechanically and electrically. A functional foundation for the device is placed in a product requirements document (PRD). The known components are modeled in CAD and placed relative to each other in 3D space. At the same time market place products and paradigms are researched to support concept development.
Concept Development – We start to formally define the mechanical envelope and the product/user interaction and we begin testing sketch and ergonomic mock-ups. Creative sketching and brainstorming is done to quickly develop concept direction. Lots of concepts are drawn, presented and down selected with the client.
Refinement - The favorite(s) are refined with more detail and once again down selected to a final choice / path. This effort involves renderings, mock ups and ergonomic development.
Mechanical Design – The ME team have been supporting the ID team in the phases above to insure DFM (Design for Manufacturability) is considered throughout. At this point all the tiny details are added to the shape including ribs, holes, switches, PCBs, cables, and many more items. This includes electrical engineering support so that the PCBs can be fully developed at the same time. Everything is done in 3D CAD layouts for the mechanical aspects.
Prototyping – We 3D print all the components we can as often as needed to physically insure we track with the product requirements as well as component fitment and human interface aspects. This is a looping process that is the quickest way to mature the design.
Mechanical Drawings, Bills of Materials, Release - This documentation is done and the product is released to production. Fabrication vendors are involved in the design review process starting at the Mechanical Design phase to insure there are no surprises when it is time to start production.
Battery Challenges
The curved earpiece created extra challenges because most batteries are rectilinear. We needed to place the battery behind the ear for weight balancing reasons. The small space available impacted the allowable size and shape of the battery. We created a curved product surface needed for human fitment and aesthetics. These had to be stretched very carefully to allow a rectangular battery to fit. Hence the classic battle between having enough energy storage without making the device too large. Contoured batteries are coming which will make wearable volumetrics much more efficient.
Using SolidWorks, we build full 3D models (assemblies and components). Working with the electric team, we develop the circuit board layouts, defined connector positions, mounting points, placement of control buttons, LEDs, camera and batteries. DFM (Design for Manufacturability) was important because great products are only possible if you can make them cost effectively.
We developed early prototypes and quickly optimized the design for system performance objectives:
Limit critical temperature, stress, or vibration response
Minimize weight and cost
Balance product weight distribution to allow it to rest comfortably on the ear.
Included copper rod in camera to battery portion of enclosure to insure a deformable fitment option for different human ear shapes.
Maximize performance and reliability
