A Wireless Sensor System for Biopotential Recording in the Treatment of Sleep Apnea Disorder

Development in micro-electronic-mechanical systems (MEMS), wireless communications and digital electronics recently have made it possible to develop small size, low-power, low-cost sensor devices. Such devices can integrate data processing, communications and sensing capabilities. A wireless sensor network (WSN) consists of a group of sensors or nodes, linked by a wireless medium (infrared or radio frequency) to perform distributed sensing tasks. Wireless sensor networks will have many applications such as surveillance, environmental monitoring, security and medical sampling. Many successful sensor applications have been deployed in very specialized networks, such as UCBerkeley's Smart Dust [1], MIT's, μ-Adaptive Multidomain Power aware Sensors [2] and UCLA's Wireless Integrated Sensor Networks [3]. Sleep apnea is very common disorder that affects millions of Americans, which is characterized by brief interruptions of breathing during sleep. The goal of this project is to develop a wireless system capable of recording from a large number of electrodes (map human bodies' biopotentials) to diagnose the disorders of sleep apnea. This research focuses on: (1) developing application program for a project called "Sleep Apnea BioPotential Imager" based on Crossbow sensor network product [4]; (2) quantifying performance of this project.

I. Introduction

Wireless Sensor Networks (WSN) have emerged as a new information-gathering platform with a large number of self-organized sensing nodes. These networks can be used in many environments such as intelligent battlefields, smart hospitals, earthquake response systems, and learning environments. In biomedicine or health field, sensor nodes can be deployed to monitor patients' health indicators and assist disabled patients. Through the self-organizing infras-tructure, nodes are able to accept queries from remote sites, interact with the physical environment, respond to the sensor readings, and relay sensed information through its multi-hop sensor networks. Sleep apnea is a very common disorder that affects millions of Americans, characterized by brief interruptions of breathing during sleep. Population over 65 will grow threefold the next fifty years from 30M to 90M. Sleep disorders will grow from 70M to 100M in the same time frame [5]. Current diagnosis system consists of metal electrodes attached to the patient and connected with wires to external electronics for signal amplification, filtering, and processing. Such a system limits the free movement and comfort level of the patient. Our effort has been fulfilled to develop a wireless system capable of recording from a large number of electrodes that map the body's biopotentials (so our project is named as Bio Potential Imager).