A Protocol for Automatic Sensor Detection and Identification in a Wireless Biodevice Network

he traditional way to build medical biodevice networks requires the attachment of an array of devices and sensors to a central data acquisition/control unit via a network of wires. While wires may be viewed as reliable links for the delivery of power and data, they can also pose a serious safety hazard. Transcutaneous wires limit patient mobility, provide paths for infection, and pose a logistical nightmare for medical personnel who must deal with them. Furthermore, as biodevices continue to shrink, the wires supplying power and data communications will limit the number biodevices which may be implanted thus eliminating the benefits of sensor fusion [1]. These problems are especially troublesome when measurements need to be taken over extended periods of time. Eliminating the wires, which supply power and transmit data, solves many of these problems [2]. Wires are eliminated by direct implantation of the biodevices. This is possible because in recent years, transducer devices have appeared which are very small and thus suitable for implantation. (Some examples of sensors include pressure, temperature, chemical, and flow rate transducers. Examples of actuators include cochlear, muscular, and nerve stimulator transducers.) Transducers may be combined with tiny microcontrollers to allow for sophisticated data collection and processing. Finally an electronic circuit, used to supply power and data to the microcontroller and transducers, completes the wireless biodevice package. Many of the issues involved in supplying power and data communications to a single implanted wireless biodevice have been described previously [ ]. This paper considers the issues that arise when multiple subcutaneously implanted wireless biodevices are controlled via a network of interrogators.