The PSI Board: Realizing a Phone-Centric Body Sensor Network

When designing a body sensor network, the mobile phone is a natural design point for data aggregation services. However, there is a missing bridge that allows sensors to communicate with existing commercial phones, even if they already possess sufficient storage and processing capabilities. The PSI board is a small expansion module that interfaces body sensor networks with commercially available cell-phones through a standard MMC/SD slot. Adding this expansion capability allows researchers to extend phone devices with additional capabilities, allowing the devices to easily serve as the hub of a wearable body sensor network. The PSI board has an integrated switching mechanism allowing transparent access to an MMC/SD card, an embedded microcontroller, accelerometer, expansion connector, and an IEEE 802.15.4 radio that can connect to a variety of commonly available wireless sensors. The capabilities afforded by the PSI board enable several new applications that would be difficult to implement given the sensors and capabilities currently found in existing cell-phone platforms.