Matsuoka, a winner of the MacArthur genius award, last year left her job as a vice president at Google-owned Nest.
Her plan to take a job at San Francisco-based one-to-many messaging service Twitter was derailed last year by a "life-threatening illness," Matsuoka wrote in an online post at medium.com.
"A new future has begun to fill my mind again," she wrote at the time, saying medical treatment was working and she had yet to work out new plans for her future.
"When you get another chance at life, there's an opportunity to start from scratch and I feel so lucky to have this."
Matsuoka will answer to Apple chief operating officer Jeff Williams, who oversees health projects, including software kits that let application makers or researchers take advantage of capabilities of the iPhone and the Apple Watch.
The MacArthur Foundation website described Matsuoka as a leader in the field of neurorobotics, a field that combines robotics with how the human nervous system coordinates muscle and skeletal movements.
In 2009, she helped start Google X Lab devoted to "moonshots" such as self-driving cars and Internet-linked eyewear. Matsuoka became part of the Nest team after Google bought the startup two years ago.
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