NightBuds - Our Development Journey
Pre-Order today: http://nightbuds.co.uk/
We wanted to give you a more in depth insight into the development of our latest product, and some of the design and development choices made over the course of the last 20+ months.
The seeds of the NightBuds were planted long ago, closer to when we founded Kokoon. Back then technology limitations (Sensing, Power consumption) meant that a product like NightBuds would have been extremely challenging to execute, so we kept the concept in the back of our minds. The more we spoke with our customers, kept track of technological developments and worked with our sleep science partners, the more the concept behind NightBuds began to emerge.
February 2019 saw us turn this concept into a project with the creation of our Product Brief. Project objectives and requirements were outlined and we undertook extensive initial market, technology and user research to ensure we formed solid foundations to build the product upon. We drew heavily on first hand customer feedback from our first headphone gathering feedback from over 3,500 customers.
April - May 2019
Initial Concept/Research Stage
Early earbud concept sketches
Armed with our market research and defined project requirements, our Mechanical Design Engineer, Joel, began working on our initial concept and collecting the data we’d need in development.
We collected various anthropometric datasets, to study the ear in depth. We also began the initial appraisals of different possible solution architectures, drawing up some rough concept sketches.
With the initial architectures assessed, Joel and the team also began to consider options to implement for sleep sensing, Bluetooth solutions and other implications the new, smaller in-ear design would have on the electronics of the design.
‘Design language’ 3D sketch
First prototyping and testing iterations
In June 2019 we progressed from initial concepts sketches and began exploring the different design elements in more depth.
In order to keep the earbud secure during the night, and not at risk of moving around and becoming uncomfortable, or falling out of a user’s ear, we settled on using a “hook” in the earbud design. To evaluate different ear hook designs, we began by comfort testing various models already available on the market.
Testing different ear-hooks
From there, we began to create our own prototypes based on our findings, using them for internal comfort testing.
Early (functional) earbud designs
First ‘feels like’ prototype for comfort testing.
Initial ‘feels like’ prototype internal testing
During this period, we also began exploring different cable types and designs, to secure the headphone to the small connector at the back of the head, housing the electronics, battery and USB-C connector. We had the challenge of designing a cable which would be flexible enough for various head sizes, and which would move with a user if they moved around in their sleep, without causing any discomfort. We also tested various earbud cable exit strategies, for the same requirements.
Engineering PoC (proof of concept) and key component layout
October 2019 - June 2020
Ongoing comfort testing and design refinement
Cable concept testing
October 2019 saw Joel move on from Kokoon, handing over the task of leading the design team to our new Senior Product Design Engineer, Guillaume.
Guillaume hit the ground running and continued to work with the team to bring our prototype forward with successive comfort tests and tweaks to the design. Comfort testing was also ramped up, with the beginning of overnight comfort testing.
This period in the design process also saw the beginning of external comfort testing, as we invited backers from our previous Kickstarter campaign to comfort test the various prototypes. We’re extremely grateful for everyone who took part in this testing, and for helping us to gather more data on comfort and fit of the new design!
With each iteration of the prototype, both internal and external comfort tests were recorded via feedback forms for analysis by Guillaume. The results were then used in each round to make further improvements to the design, in some cases with various proposals tested to find the best resolution to an issue highlighted in testing.
Earbud comfort testing
Snippet from our internal test results analysis evolution spreadsheet
Below, we’ve included some of the key design changes which were made over the course of our comfort testing, shown through the evolution of the earbud design:
Concurrently with the testing and changes we were making to the prototype, we were also working on the integration into and testing of the PPG sensor in our design in March and June 2020.
PPG sensor on PCB tested
The sensor was initially positioned in version C2V3_C of the prototype (as seen above), before being repositioned in C2V6_A in order to ensure better contact. Testing established the new position enabled the sensor to take consistent readings throughout a night’s sleep. At this stage we began testing for data validation, using a prototype with fully integrated sensors.
PPG sensor and electronics integrated into prototype for testing
This was used for overnight sleep tests, where testers were also required to wear a heart rate sensor on a chest strap. Using both sets of data, we were able to confirm the accuracy of our PPG sensors.
During this period, we also began working with our new factory, after an extensive selection process.
Electronics/Software Development board
September 2020 saw the completion of our electronics “Development” board. Work initially began on the board back in December 2019, and had been ongoing throughout the design process.
The Development board contains all the electronics present in the NightBuds, but with extra test points and debug/programming access. It is used for embedded software development, electronics test and characterisation and also for app development purposes.
Toward the end of the month we were happy to receive fully working factory samples. These samples passed the key functional tests and proved very helpful in testing to help us identify outstanding UX and aesthetic issues to resolve.
Version 1 Development board CAD
Version 2 Development board