An ultra-low power, self-organizing wireless network and non-invasive biomedical instrumentation

This paper presents a newly developed short-range, ultra-low power wireless device called the "i-Bean", an ad hoc, self-organizing network protocol, and their application to ambulatory bioinstrumentation using a novel finger photoplethymographic sensor called the "Ring Sensor". The i-Bean is made of commercial, off-the-shelf components, and functions as an integrated RF transceiver as well as data acquisition and processing device. The innovative design of the i-Bean circuitry results in extremely low power consumption for the device to run on a compact battery for exceptional long periods. A proprietary protocol allows multiple i-Beans to form ad hoc, self-organizing networks with optimal power efficiency. The Ring Sensor can measure arterial blood volume waveforms and blood oxygen saturation non-invasively and unobtrusively from the wearer's ringer base. Combining the i-Bean and the Ring Sensor, a fully self-contained, wearable instrument has been developed ideal for on-line, long-term and continuous monitoring of vital signs.