Former Apple Watch architect reveals heart-rate sensor design process


Apple Watch sensors
Getting accurate heart rate sensors here wasn't easy.
Photo: Jim Merithew/Cult of Mac

The Apple Watch is known for having one of the best heart-rate sensors among smart watches, but according to former Apple platform architect Bob Messerschmidt, getting a super accurate reading wasn’t an easy task.

Messerschmidt joined Apple in 2010 after Steve Jobs acquired his company and set him to work on the Apple Watch team. In a new interview that reveals some of the design process that went into Apple Watch, Messerschmidt says he originally wanted to put the heart rate sensor in the Apple Watch bands.

Instead of getting a reading from the top of the wearer’s wrists, Messerschmidt told the design team he was going to put the sensor on the underside of the Apple Watch band. The idea was rejected because Apple wanted to have interchangeable bands without sensors.

“At the next meeting I would go ‘we can do it here (on top of the wrist), but it’s going to have to be kind of a tight band because we want really good contact between the sensors and the skin,'” Messerschmidt told Fast Company. The answer from the design studio would be ‘no, that’s not how people wear watches; they wear them like really floppy on their wrist.'”

Apple’s strict design requirements and focus on user experience forced Messerschmidt’s spectroscopy team to develop new engineering solutions to make customers happy, something he says is unique to Apple.

The interview touches on a number of other areas of what it’s like to work at Apple, including how Steve Jobs solved the company’s power struggle between marketing and engineers, as well as how Apple is a giant corporation that’s run like a startup.

The unconventional corporate structure gives Apple employees access to more resources than at other tech companies. Instead of having to worry about budgets, engineers put in requisitions telling executives what they want to do and how many people they would need for the team. Depending on how amazing the idea is, engineers could get massive resources instantly.

“If you went to Harvard Business School and said you’re going to operate a company with that much annual revenue with one profit center, they’d say ‘no, that’s not going to work,'” Messerschmidt explained. “It flies in the face of what’s being taught at business schools, but it does work. It has worked. I believe in the structure.”


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