Biosensors Detect Sleep Apnea Via Wearable, Home-Based Test

July 23, 2020

Christine Young  By: Christine Young
 Blogger, Maxim Integrated 


Do you feel rested after a night's sleep? If you're like many people, the answer may be no. According to sleep researchers, nearly one billion adults have mild to severe obstructive sleep apnea and more than 85% of them are undiagnosed. Obstructive sleep apnea (OSA) is characterized by interrupted breathing during the night. Even though the afflicted person is trying to breathe, the muscles in the back of the throat do not keep the airway open, triggering fragmented sleep and low blood-oxygen levels (SpO2). A Frost & Sullivan study commissioned by the American Academy of Sleep Medicine notes these costs associated with undiagnosed OSA:

  • Workplace accidents: $6.5 billion
  • Motor vehicle accidents: $26.2 billion
  • Lost productivity: $86.9 billion
  • Comorbid diseases: $30 billion

Traditionally, OSA is diagnosed through a sleep study performed overnight in a hospital. But Leuven, Belgium-based Ectosense has created a more convenient and less costly way to evaluate for the condition: a home-based test using a wearable device. Worn on the finger, the NightOwl® home sleep apnea test detects drops in SpO2 and other important changes in the photoplethysmography (PPG) signal collected by the biosensor inside. There's a 3-day rechargeable version and a 10-night disposable option, along with a smartphone app that transmits diagnostic data to the prescribing healthcare professional. The NightOwl home sleep apnea test recently achieved U.S. Food and Drug Administration (FDA) approval. Incidentally, since the vital signs measured by the NightOwl can also be indicators of pneumonia (or infection), the devices may be of use in remote monitoring of COVID-19 patients.

NightOwl Home Sleep Apnea Test Featuring Maxim Integrated BiosensorsEctosense's NightOwl home sleep apnea test tracks relevant parameters over the course of multiple nights to provide an assessment.

To create its coin-cell battery-powered device, Ectosense sought a small, low-power biosensor that delivers good PPG quality. Following a thorough evaluation, the company selected Maxim Integrated's MAX30102 pulse oximeter and heart-rate biosensor module. The module includes internal LEDs, photodetectors, optical elements, and low-noise electronics with ambient light rejection. The MAX30102 provides low-power heart-rate monitoring (<1mW) and low shutdown current (0.7µA). "I'm confident to say, as a user of all present-day alternatives, that Maxim's components are far ahead of those of alternative suppliers in terms of providing high-quality PPG readings," said Bart Van Pee, Ectosense's cofounder and COO.

The reusable NightOwl utilizes the MAX30102, while the disposable version uses the MAXM86161 optical data acquisition system. The transmitter side of the MAXM86161 has three programmable high-current LED drivers. Its receiver side has a high-efficiency PIN photodiode and an optical readout channel, which has a low-noise signal-conditioning analog front-end (AFE). The AFE features a 19-bit ADC, an ambient light cancellation circuit, and a "picket fence" detect-and-replace algorithm. With its low-power operation (<10µA optical readout channel, 1.6µA shutdown current), the MAXM86161 enables compact, power-efficient wearables.

By designing with these biosensors, Ectosense met its requirements for high-quality PPG readings from small, power-efficient sensors, saving four months in clinical validation time. Using discrete components would have required a longer validation cycle. "It's quite amazing that we have FDA approval of a device that houses a Maxim chip that only recently became available," Van Pee said of the fast validation and design integration process using the MAXM86161.

This blog post was adapted from the Ectosense customer testimonial; read their story to learn more.