Microsoft Band

Andrews-Cooper engaged with Microsoft to help design and engineer their initial release of a fitness tracker/smart watch.

The Approach

The project included advanced design for fit and integration of unique technology including an optical heart rate sensor.  This resultant design, test and optimization to enable a reliable sensor set in a very small form factor.  In addition, several new manufacturing techniques were introduced and required to complete the project.

The Project

A-C was part of a team of engineers that included Industrial Designers, Mechanical, Electrical and Manufacturing Engineering.  Specific A-C responsibilities focused on Mechanical and Manufacturing Engineering.  Aspects of our Design Work included:

  • Iterative Design Work with Industrial Designers
  • Advanced CAD Surfacing
  • Electronic Packaging
  • Mechanism Design (adjustable latch)
  • Analytical Modeling
  • Design for Manufacturing


A-C engineers supported the development of a wearable device that had never been built before.  Some important details:

  • A Unique Sensor – Andrews-Cooper took a sensor concept from a sensor design consultant and optical requirements from the client’s optical engineering team and translated them into a compact, water-sealed, manufacturable sensor. Key elements included:
    • Miniature LED light sources
    • Light pipes for directing the light output
    • Bandpass filter for ambient light rejection
    • Miniature injection molded collection lens
    • Light receiver
    • Light isolation barriers to prevent crosstalk between light sources and receiver.
  • A Complete Sensor Set that included:
    • Heart Rate Monitor
    • GSR Monitor
    • GPS & Bluetooth antenna
    • Microphone
    • Temperature Sensor

Design Challenge

Fitting the extensive features within severe space and volume constraints was a key challenge.  All this was accomplished while the underlying technology was itself under significant iteration.  Andrews-Cooper engineers worked with industrial designers to:

  • Develop an analytical model to predict sizing of the band
  • Develop an overmold strategy to contain the sensors, battery and display while ensuring a comfortable and visually appealing device
  • Focus on fit/finish extensively


  • Faster time to market
  • Available resources met gap in client team
  • Expertise provided around advanced surfacing


  • Design


  • Materials – TPE, sheet metal
  • Manufacturing Methods – metal injection molding, over molded TPE and ABS, complex tooling 
  • Packaged Electronics
    • Electrical Components – micro connector, small scale, flexible circuit
    • Switches – micro

Consumer Product Case Studies