Oura, maker of a health-monitoring smart ring for consumers, has raised $28 million in a new Series B funding round, CEO Harpreet Singh Rai announced today in a medium.com post.

Forerunner Ventures, Square and Google's Gradient Ventures participated in the raise. The first two groups will be rewarded with spots on Oura's board of directors, while Gradient Ventures Founder and Managing Partner Anna Patterson will become a board observer.

The wearables company also announced that Dr. Matthew Walker, a professor of neuroscience and psychology at the University of California, Berkeley and a well-published sleep researcher, will be joining Oura as a chief science advisor.

WHAT THEY DO

The Oura Ring hosts a number of different sensors designed to monitor the wearer’s health while they sleep or engage in physical activities. These include an NTC body-temperature sensor, infrared LEDs to actively measure blood-volume pulse, and an accelerometer and a gyroscope to detect movement. The wearable feeds all of these readings through an accompanying app that uses artificial intelligence to generate insights and behavior-change suggestions for the user.

The Finnish company has enjoyed support from a diverse cadre of investors over its lifetime. Its previous fund-raises have included tech leaders such a YouTube cofounder Steve Chen and Twitch cofounder Kevin Lin, as well as celebrity athletes like Shaquille O'Neil, Lance Armstrong, Manu Ginobili and Nick Foles.

Today's update included new milestones for Oura. Rai wrote that the startup has sold more than 150,000 smart rings to date, and has grown its international team to more than 100 employees.

WHAT IT'S FOR

Rai wrote that Oura's new funds will help the company acquire new staff members "that can help further our commitment to helping people live healthier lives starting with better sleep." Further, the company will be revamping its branding and marketing efforts and targeting new research efforts in collaboration with academic institutes.

MARKET SNAPSHOT

Despite landing on the higher end of the consumer health wearable price scale, the Oura Ring has a fairly strong public image and even drove headlines when Prince Harry was spotted with the device on his finger. The past couple of years have seen the company flesh out the platform's wellness-tracking capabilities, having integrated their service with Apple Health and other health-monitoring services.

But Oura's device is still competing with a bevy of connected smartwatches and trackers, not to mention other wellness-focused smart rings. Examples of the latter include Motiv, which offers a selection of smart rings that interact with fitness apps, and New York City-based Ringly, which also adds bracelets to its mindfulness offerings.

ON THE RECORD

"Improving your sleep is the first step in spurring better habits and ultimately preventing avoidable health issues. We’ll continue to apply data and insights to understand larger, sweeping trends and preventative care as we elevate human health. Now, especially during these tough times, and well into the future," Rai wrote.