Bringing The Power Of Wireless To Medical Applications

Introduction

Portable instruments such as blood pressure monitors, pulse oximeters, spirometers, and heart rate monitors are the doctor's tools of the trade in intensive care. And, thanks to modern electronics, this equipment delivers the accuracy, reliability, and repeatability that is critical in life-and-death situations.

Unfortunately, because the sensors for these instruments are typically attached to the patient by wires, the patient becomes bed-bound. Moreover, caring for the patient becomes awkward, because all the instrumentation has to be disconnected and later reconnected each time the patient needs to be moved.

Adding low-power, low-cost wireless technology could eliminate this tedious job, freeing the patient from the instrumentation and the bed. These wireless devices could use their embedded RF link to communicate with a gateway that connects to the hospital LAN/WAN and transmits to a centralized hub for control, monitoring, or further analysis.

At first glance, IEEE 802.15.x standards-based RF wireless technologies such as Bluetooth, or its lower-powered cousin ZigBee, would appear the obvious choice for adding wireless to medical equipment. After all, both have been marketed aggressively courtesy of members of the Bluetooth Special Interest Group (SIG) or ZigBee Alliance. In addition, a lot of work has gone into these technologies to ensure compatibility, and there are plenty of chipsets available from major silicon vendors.

However, for certain specialist applications, both Bluetooth and ZigBee have some disadvantages. First, they are relatively expensive and likely to remain so as the semiconductor companies attempt to recoup their huge investment in ensuring compatibility. Moreover, qualifying the product to the standard adds costly nonrecurring engineering (NRE) charges. And, due to relatively inefficient protocols, power consumption is comparatively high – a major drawback in battery-powered devices.