Zephyr and Curie Team Up for Neonatal Wearable for the Developing World
The Zephyr Project is still a babe in the technological woods, so it’s only fitting that the open source real-time operating system is driving an innovative wearables solution that aims to improve healthcare for infants. At the recent Embedded Linux Conference Europe, Teresa Cauvel, CTO and co-founder of Chicago-based neonatal health technology startup Neopenda, explained how her company built a neonatal monitoring bracelet for hospitals in the developing world using an Intel Curie module running Zephyr. The complete talk, called “Leveraging IoT Biometrics and Zephyr RTOS for Neonatal Nursing in Uganda” can be seen in the video link below.
Cauvel and co-founder and CEO Sona Shah came up with the idea for Neopenda as graduate students in biomedical engineering at Columbia University. The partners hoped that a new U.N. Sustainable Development goal for ending preventable deaths of under 5-year-olds by 2030 would provide numerous opportunities for technological innovation. “With IoT we can reimagine what’s possible in global health,” Cauvel told the ELCE audience.
Cauvel and Shah decided to develop a wearable for neonatal patients in the first 28 days after birth. They focused on developing countries where 98 percent of preventable neonatal deaths occur and where every year 46 million newborns have complications at or around birth that require special care and treatment. Some 3 million newborns die from these complications. However, 80 percent of the victims die from preventable causes or could have saved by affordable treatments. “Reducing infant mortality is a solvable problem,” said Cauvel.
The problem is being attacked on several levels, from improving transportation to hospitals to developing better treatments for pre-term birth, birth asphyxia, and severe infections. Neopenda is focusing on improving pediatric hospital care. When researching the problem in Uganda in 2015 with the help of the Uganda Paediatric Association, the co-founders discovered there were large unmet needs in monitoring and diagnosis.
“Early detection of distress is really key in newborn care,” said Cauvel. “We want to help staff better manage a large quantity of patients. There are so many critically ill newborns that need care and not nearly enough nurses, doctors, equipment, and supplies. Typically, you might see two nurses responsible for 50 to 75 babies. Standard equipment like vital signs monitors is often prohibitively expensive.”
In early 2016, the partners founded Neopenda with the help of a Kickstarter campaign, as well as grants from Cisco and Vodafone. They started working on a prototype for a wearable vital signs monitor designed for newborns in low resource hospitals. The wearable, which is due to enter trials in Uganda in 2017, is strapped to infants’ foreheads, and measures heart rate, respiratory rate, blood oxygen saturation, and temperature.
“These are all of critically important vitals to track in newborns,” said Cauvel. “They show danger signs when conditions are changing, and help monitor health status.”
The biometrics devices wirelessly communicate to the central monitor, which can be a laptop, tablet, or smartphone, where results are displayed with visualizations. “Health workers can view the status of all the babies and be alerted in real time when newborns are in distress,” said Cauvel. “It helps the staff triage while also providing more detailed information to guide treatment and diagnosis.”
Prototyping: From Arduino to Curie
In choosing a technology platform, Cauvel and Shah had several key requirements: The device needed to run on batteries using minimum power, and be rugged enough to resist dust, heat, humidity, and wear and tear. It needed good support for wireless and sensor technology, and be sufficiently scalable to support larger hospitals as well as clinics. It also had to be highly affordable. Neopenda aims to reduce the cost to about $50 per wearable, which is very low for medical monitoring devices.
The initial prototype was built around an Arduino Uno, followed by a model that used the Uno’s ATMega328 MCU breadboarded with WiFi and the most essential components. Power considerations led quickly to swapping WiFi for Bluetooth Low Energy (BLE), which also raised fewer questions about radiation risks.
The current iteration uses the Intel Curie module, which runs Zephyr on an x86-compatible Intel Quark SE CPU. The dime-sized Curie offers the advantage of being smaller, more affordable, and more power efficient than an Arduino. It also furnishes an ARC EM4-based sensor subsystem and a built-in BLE radio, and its 80KB of SRAM makes it more suitable for complex BLE applications.
The Curie’s interfaces between these components and the Quark SE saved a lot of time, as did the availability of a Curie-equipped Intel Arduino 101 board, used for prototyping. Meanwhile, the Curie’s pattern matching engine and 6-axis sensor may hold potential for future applications, said Cauvel.
The ARC subsystem controls the Curie’s 12-bit ADC, which “enables us to make accurate DSP measurements,” said Cauvel. The device incorporates a LilyPad MCP9700 temperature sensor, as well as a pulse sensor from pulsesensor.com. Neopenda developed an algorithm that derives the respiratory rate from the pulse rate.
For pulse oximetry, the developers breadboarded a sensor using red and infrared LEDs with a TSL235 light-to-frequency converter. To generate a blood oxygen saturation measurement from this setup, “we multiplexed between the two LEDs to calculate the absorption ratio, and used the GPIO driver and its callback API to calculate frequency,” explained Cauvel.
Zephyr played a key role in the success of the wearable prototype, thanks to its modularity, support for constrained systems, and more advanced capabilities compared to the Arduino IDE. “Zephyr turned out to be a big step up from Arduino because it supports the ARC core, the DSP subsystem, and the x86 host concurrently,” said Cauvel. “Zephyr also supports multi-fibers and interrupts for complex sensor manipulation and communication so it can cleanly handle the data coming in from different sensors simultaneously.”
The developers also benefited from “Zephyr’s rich support for drivers and sensors, as well as sample code and a reliable SDK with cross tool chain,” said Cauvel. “There was already a BSP supporting the Arduino 101 with tool chain to compile for the DSP subsystem in the ARC processor and the host processor. This enabled quick installation of the compiler and tool chain in just a couple of hours, and with the help of the Eclipse IDE, we were able to get the GDB debugger working with DSP and host.”
Cauvel went into more detail about various past and current modifications of each sensor algorithm. Currently, most sensor readings are close to the reliability range of expensive commercial sensors, except for respiratory. “We may need to add Fourier transforms to get better accuracy on respiratory,” said Cauvel. The company has also developed an Android app that interprets the BLE signals and displays data and visualizations.
Cauvel is confident the device will be ready for trials in Uganda in 2017. Neopenda is working on getting a CE mark for certification, and they will need to get approval of the government of Uganda. The plan is to expand in East Africa and beyond. Soon, Cauvel hopes to give thousands of newborns in low resource settings “the healthy start they deserve.”
Watch the complete presentation:
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