This paper presents a Body Area Network (BAN) gateway to Android mobile phones for mobile health applications. The proposed approach is based on a Secure Digital Input Output (SDIO) interface, which allows for long-term monitoring since the mobile phone hardware can be extended in order to operate with ultra low-power radios.
The software architecture implemented on the mobile phone enables a number of important features. Data can be displayed, further processed or sent to a remote server exploiting the WLAN or 3G networks. Moreover, the system allows to configure thresholds on the measured parameters and to automatically send alerts such as SMS messages and emails based on these values.
The system described here is for ambulatory ECG monitoring. It offers high computing power, personalization, high connectivity, and requires very little training in the technology, since users can use their own mobile phone to benefit from mobile health services.
We present a mobile health monitoring system that uses the Human++ BAN sensor nodes to retrieve bio-signals from the body and an Android mobile phone to collect, store, process, and send the data. It represents an energy-efficient alternative to Bluetooth. The base station is composed of three main components:
1 – A microcontroller (MSP430 series),
2 – a radio (nRF24L01+ 2.4 Ghz, by Nordic) and
3 – a synchronization logic block.
Ideally the use of an SDIO controller capable of handling the SDIO communication with the mobile phone and presenting itself as a simple serial interface to the microcontroller. But this solution leads to a limited data throughput, as well as to higher power consumptions (higher clock frequency and additional controller).
For these reasons we developed a novel approach that combines the use of an SPI interface, present in all low-power and low-cost microcontrollers, but with communicates with the smartphone by means of the SD protocol. The whole protocol is then implemented in firmware on the MSP430. Emulating the SD protocol over the SPI interface enables the smartphone to communicate with ultra-low power radios, increasing the autonomy of the BAN (e.g. compared to Bluetooth based body area networks).
We selected ECG monitoring as a case-study for our connected health platform demonstration. The ECG is monitored using an ultralow-power wireless ECG necklace developed by IMEC, which uses a body area network and an optimized implementation of a CWT based algorithm In order to determine the heart rate of the user, it can be configured with different thresholds such as minimum or maximum heart rate values).
Based on these thresholds it is possible to trigger alerts, such as emails or SMS messages to one or more people (medical staff, relatives) who need to be informed about the changes in the ECG activity.
Additionally, the application allows the user to visualize and send a daily summary of the heart activity, reporting the minimum, maximum and average heart rate. Finally, data can be sent through Wi-Fi to a remote server, in order to collect or further process it.
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