Nordic-powered wearable uses arterial signal-analyzing algorithm to accurately measure and report indicators of suboptimal health

Courtesy of Nordic Semiconductor

‘SPO2 Wristband Solution’ from Veepoo employs Nordic’s nRF52832 SoC to wirelessly monitor users’ blood oxygen saturation values and linked sleep apnea syndrome

Nordic Semiconductor today announces that China-based, Veepoo, integrates Nordic’s award-winning Bluetooth® Low Energy (Bluetooth LE) nRF52832 System-on-Chip (SoC) in its ‘SPO2 Wristband Solution’. The product enables OEMs without RF design expertise to rapidly develop health-based wearable solutions for the middle-aged to elderly, smokers, and other people with suboptimal health, particularly those with interstitial breathing, heart disease, or sleep apnea syndrome.

SPO2 Wristband Solution allows OEM develpers to design products that monitor arterial oxygen saturation and in turn estimate the oxygenation capacity of the lung along with the blood’s hemoglobin carrying capacity. Nordic’s nRF52832 SoC provides Bluetooth LE wireless connectivity between the wristband and a Bluetooth 4.0 (and later) iOS or Android smartphone.

From the smartphone, users can access important health updates via Veepoo’s companion app. For example, the app allows users to monitor the change in blood oxygen during nocturnal sleep and therefore to test for abnormal metabolism, hemodynamic disorder, or sleep apnea syndrome. If blood oxygen saturation decreases to a hazadous level, the wearable device will automatically trigger an alarm to warn the user and/or caregiver of the danger.

The Nordic SoC’s 64MHz, 32-bit ARM® Cortex® M4F processor provides ample computing capacity to power Veepoo’s unique algorithm which enables the SPO2 Wristband Solution to accurately measure blood oxygen saturation values from weak arterial signals at the wrist in addition to the strong signals from the fingers. Standard medical devices are limited to finger measurements only.

The device’s algorithm capitalises on the fact arterial blood absorption of light varies with arterial pulsation. In addition, oxygenated and deoxygenated arterial blood hemoglobin have different light absorption rates at different wavelengths. A photosensitive element embedded in the hardware detects changes in arterial pulsation and light absorbtion due to varying oxygenation levels and the software eliminates the effects of non-blood tissue then calculates actual blood oxygen levels.

The low power consumption characteristics of the Nordic SoC help prolong the service life of SPO2 Wristband Solution’s portable lithium battery, meaning it can charge and discharge approximately 7000 times while supporting 15-plus days of standby time―an important consideration for a health-based wearable.Nordic’s nRF52832 Bluetooth LE SoC, a member of Nordic’s sixth generation of ultra low power (ULP) wireless connectivity solutions, combines the ARM Cortex M4F processor with a 2.4GHz multiprotocol radio (supporting Bluetooth 5, ANT™, and proprietary 2.4GHz RF software) featuring -96dB RX sensitivity, with 512kB Flash memory and 64kB RAM. When launched, the SoC was the world’s highest performance single-chip Bluetooth LE solution.

The SoC is supplied with Nordic’s S132 SoftDevice, a Bluetooth 5-certified RF software protocol stack for building advanced Bluetooth low energy applications. The S132 SoftDevice supports Central, Peripheral, Broadcaster, and Observer Bluetooth low energy roles, supports up to twenty connections, and enables concurrent role operation.

“We selected the nRF52832 SoC for its superior technical aspects,” says Jiuchao Li, CEO at Veepoo. “The powerful CPU computing capability meets our algorithm requirement and supports floating point operation, the RAM and Flash meet our specification requirements, and the low power characteristics ensure SPO2 Wristband Solution can be used for a longer period of time.

“Our SPO2 Wristband Solution benefits from the clean separation between Nordic’s SoftDevice and the application code, allowing our engineers to work directly on application software. The easy-to-use Software Development Kits [SDKs] also greatly reduce the development challenge,” says Jiuchao Li.

“Throughout the SPO2 project, Nordic application engineers have provided us with fast and helpful responses to our enquiries, which has contributed to a smooth R&D schedule.”

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