Rockley Photonics puts lasers on a chip for medical sensors

This story was originally published in my Sept. 30 newsletter. 

Rockley Photonics, which began its life using photonics for communications between computers, has been building chips to manage light for the past nine years. With photonics, light is used instead of electricity to send data. After being used to send data (as in fiber networks) for years, it’s increasingly being used inside data centers for sending data at speeds as fast as, well, light.

But with its latest chip, introduced last week, Rockley has managed to create a medical-grade sensor that can use light to detect an array of vital signs and even blood chemistry, all packed into a module roughly the size of a dime.

The resulting sensor can measure heart rate, blood oxygen, blood pressure, temperature, blood alcohol level, glucose, and other metabolites in the blood. This sounds almost impossible if you think of measuring key vitals in a traditional manner, but the sensor is giving an algorithmic approximation based on how the light shined into the person’s skin reflects back into the sensor.

Fitness trackers usually use some form of green or red LED to track how much light is absorbed when a laser shines a light into the skin. The new sensor from Rockley works in a similar fashion, except it’s not limited only to red or green light. The sensor can pack hundreds of wavelengths of visible light into a small space, then combine those different wavelengths to understand the chemical composition of the blood.

That’s how it estimates blood alcohol level, lactic acid, and other elements. Using spectroscopy in this way is not unusual. When scientists want to understand the chemical composition of something, they pop it into a spectrophotometer to observe how it absorbs light. Spectrophotometers are sized for countertops (they’re roughly the size of a phone or old-school credit card reader machine) and cost between $1,300 and $3,000.

Rockley has managed to compress the capability of a countertop scientific instrument into a module that can be worn on a patient’s arm, chest, or wrist. It’s still pretty expensive, though. Andrew Rickman, CEO of Rockley, didn’t tell me exactly how much the module would cost, but said it would be somewhere around $500.

Given that price tag, this isn’t a sensor designed for the casual activity-tracking market. Instead, it’s aimed at medical devices, with Medtronic as the first customer. Medtronic will produce its first devices based on the sensor later this year and seek FDA approval for them next year.

The next challenge for Rockley will be ensuring that its algorithms are properly tuned to measure all of the things it says it can measure, almost all of the time. Rickman said that not only can the sensor measure a variety of vitals, it generates a unique signature for every person who wears it. As Rickman explained to me, each person’s skin absorbs and scatters light in unique ways, the pattern of which can be analyzed to determine someone’s skin tone, age, and biological sex.

Rickman told me that he believes later generations of chips will be able to cram more wavelengths onto themselves, enabling the sensor to detect more chemicals, and with greater accuracy. I can’t wait to see data on accuracy coming from this device, and especially look forward to a time when a doctor may not have to draw my blood to get health data.

As we saw with Theranos, such technology could be worth a tremendous amount. My hope is that unlike Theranos, Rockley has viable tech.