Nordic Semiconductor today announces that U.K.-based Waire Health (formerly Sentinel Sensors) has selected a Laird module integrating Nordic’s nRF52840 Bluetooth® 5.2/Bluetooth Low Energy (Bluetooth LE) advanced multiprotocol System-on-Chip (SoC) to power its ‘C-Detect’ Covid-19 health monitor, proximity tracker, and contact tracing wearable. The device is designed primarily to monitor the vital signs used to warn of possible cases of Covid-19 during the current pandemic.
C-Detect is a rechargable sensor solution that works out-of-the-box to continuously monitor the user’s heart rate, respiration rate, core body temperature, and oxygen saturation (SpO2). The device takes the user’s vital signs every 10 minutes for 24 hours a day and up to 10 days on a single battery charge depending on the number of interactions. Based on the vital signs readings, the device indicates if the wearer might be displaying symptoms of coronavirus infection and should therefore be tested, treated, or begin a period of self-isolation. For example, if the C-Detect unit shows amber, the user should stay or go home and self-isolate.
For greater accuracy, C-Detect is worn permanently on the upper arm where motion is limited and which largely eliminates the motion artefacts that can affect the accuracy of wrist-worn consumer devices. C-Detect’s sensor and algorithm data processing capability is powered by the integrated Nordic nRF52840 SoC-based Laird BL654 module’s 64MHz, 32-bit Arm® Cortex® M4 processor with floating point unit (FPU). The Arm Cortex M4 processor is combined with a 2.4GHz multiprotocol radio (supporting Bluetooth 5.2, ANT™, Thread, Zigbee, IEEE 802.15.4, and proprietary 2.4GHz RF protocol software) and a generous 1MB Flash and 256kB RAM memory allocation.
The Laird module’s nRF52840 SoC enables C-Detect to monitor its proximity to other C-Detect devices using the SoC’s Received Signal Strength Indication (RSSI) feature. A haptic vibration motor then provides a proximity alert to the wearers if the recommended two meters for safe Covid-19 social distancing has been breached. C-Detect won the U.K. entry for the E.U. European Institute of Innovation & Technology (EIT) Digital Token Covid-19 contact tracing solution. As a result, C-Detect can receive ‘digital tokens’ from other C-Detect units and other compatible contact tracing solutions by European partners to accelerate Covid-19 track and trace initiatives.
On-chip NFC tag
The Nordic SoC-based Laird module also pairs between the device and the user’s Bluetooth 4.0 (and later) smartphone using the on-chip NFC tag for touch-to-pair functionality. The vital signs data can then be transmitted from the device to an associated iOS and Android app on the user’s smartphone using the nRF52840 SoC’s Bluetooth LE connectivity. The nRF52840 provides full Bluetooth 5 support including 2x on-air raw data bandwidth (2Mbps); 4x range; 8x broadcasting ability with advertising extensions that increase the advertising packet payload size to 251 bytes, and an improved channel coexistence algorithm. The SoC features 95dBm RX sensitivity (at 1 Mbps Bluetooth LE) and an on-chip power amplifier boosts maximum output power of 8dBm for a total link budget of >103dBm. The nRF52840 SoC’s secure over-the-air device firmware update (OTA-DFU) feature allows continually firmware updates for C-Detect adding new features and functionality.
The nRF52840 SoC is supplied with Nordic’s S140 SoftDevice, a Bluetooth 5.2-certified software protocol stack for building long range and high data throughput Bluetooth LE applications. Nordic’s unique software architecture includes a clear separation between the RF protocol software and the developer’s application code, simplifying development and ensuring the SoftDevice doesn’t get corrupted when developing, compiling, testing, and verifying the application code. The S140 SoftDevice offers concurrent Central, Peripheral, Broadcaster, and Observer Bluetooth LE roles, and supports high throughput and long range modes as well as advertising extensions.
“Nordic offers world-leading technology that gives us the edge in terms of power consumption and performance,” says Collette McGowan, Program Director at Waire Health. “The nRF52840 SoC in the Laird module provides sufficient processing power and generous memory allocation enabling complex secure applications to be implemented at a very competitive price point.
“Nordic Software Development Kits [SDKs] are among the best around, enabling rapid prototyping and development. The concept of SoftDevice abstraction allows us to focus on core applications, leaving the complexities of the communications stack to the experts at Nordic.
“The technical and development support, reference designs, DevZone forum, and exceptional response times sets the company apart from its competitors and has accelerated our development schedule considerably.”
About Waire Health
Edinburgh, Scotland-based Waire Health was founded in 2015 to develop vital signs software solutions by a core team with a combined experience of 75 years in electronics systems design, project management in large scale digital roll outs across multiple markets, including health.
The first technology development was the company’s unique HW Sensor to capture vital signs enabling signficantly greater accuracy and intended for wearable medical devices. This breakthrough was the foundation of a successful EU Nightingale H2020 PCP tender for the Sentinel Wearable ECG device.
Realizing in early 2020 that the four main early indicators of a patient’s possible infection with Covid-19 (heart rate, respiration rate, core body temperature, and oxygen saturation) were already part of the feature set of the Sentinel device, the team has repurposed and simplified the design to deliver the world’s only fully self-contained early warning wearable – C-Detect.
The company is privately owned and based in Scotland, with design, software development and manufacture in the centre of Scotland’s academic and technology heartland – re-branding to Waire Health in August 2020.