The release of the Xiaomi Mi Mix in 2016 ignited the current full-screen smartphone trend and disrupted the market by replacing the physical infrared proximity sensor with a software-driven ultrasonic solution.
This is what the future of smartphones looks like
– Ars Technica, 2016
The Problem & Design Constraints
Since 2007, all smartphones, including the original iPhone, used an infrared (IR) proximity sensor positioned at the top of the phone. This sensor turns off the touchscreen during calls to prevent accidental input and conserve battery life. However, the need for an IR sensor at the top of the phone required valuable space, constraining smartphone designs and limiting the possibility of a true full-screen experience.
The Breakthrough Solution
Elliptic Labs’ ultrasonic proximity sensor replaced the IR sensor, allowing the screen to extend to the very top of the device. This innovation:
- Enabled a bezel-less full-screen design.
- Removed the IR proximity sensor at the top of the phone
- Provided industrial designers with greater flexibility in phone aesthetics and layout.
Philippe Starck, the designer of the Xiaomi Mi Mix, leveraged this technology to create an award-winning design that has since been added to the permanent collections of leading museums worldwide.
My Role & Contributions
Product Discovery Phase
- Original Concept: Conceived the ultrasonic proximity sensing solution and presented it to Elliptic Labs’ founder Tobias Dahl and CEO Stian Aldrin in 2011.
- Early Prototyping: Developed an Android-based prototype demonstrating the potential of ultrasonic sensing for smartphone manufacturers.
- Data-Driven Development: Implemented a data collection app that uploaded structured user test data to a SaaS backend, enabling precise algorithm refinement.
- Experience Prototyping: Built prototypes that showcased the final solution’s benefits to key stakeholders.
- Structured User Testing: Conducted controlled testing to validate real-world performance and refine sensor behavior.
Product Delivery Phase
- Worked closely with cross functional research and engineering teams to integrate and optimize the ultrasonic solution.
- Facilitated structured user testing to fine-tune the solution for real-world scenarios.
Trade-offs & Challenges
- The Xiaomi Mi Mix was a concept phone: While groundbreaking, it utilized a dedicated 40 kHz ultrasonic transducer from Murata, which was expensive and added complexities to mass market manufacturing.
- Scaling Beyond Concept: The solution proved feasible but required further refinements to become cost-effective for mass production.
Impact & Industry Adoption
- Sparked a full-screen design revolution in the smartphone industry.
- Demonstrated the viability of ultrasonic software-based sensor replacements.
- Showcased an industrial design that influenced all major smartphone brands.
- Entered the permanent collection of world-renowned museums.
- Paved the way for further advancements in hidden sensors and AI-driven sensing solutions.
What Came Next?
The Xiaomi Mix validated the potential of ultrasonic proximity sensing but required further advancements to achieve mass-market adoption. The next phase involved refining the solution for mass market production.
