Recent Advances in Impedance-Based Wireless Sensor Nodes

This paper presents recent developments in an extremely compact, wireless impedance sensor node for use in structural health monitoring (SHM). The sensor node uses a low-cost integrated circuit that can measure and record the electric impedance of a piezoelectric active-sensor. The sensor node also integrates several components, including a microcontroller for local computing, telemetry for wireless data transmission, multiplexers for managing up to seven piezoelectric transducers per node, energy storage mediums, and several triggering options including a wireless triggering circuit into one package to truly realize a comprehensive, self-contained wireless active-sensor node for SHM applications. It is estimated that this sensor node requires less than 75 mW of total power to operate measurement, computation and data transmission. In addition, the sensor node can also be used for the active-sensor self-diagnostic process that can monitor the operational condition of piezoelectric transducers used in SHM applications. The performance of this miniaturized and portable device is compared to our previous results and its broader capabilities are demonstrated.