Wireless and passive SAW devices, for Structural Health Monitoring applications.

Surface Acoustic Wave (SAW) passive and wireless sensors are a promising solution for condition and structural health monitoring (SHM) applications. They are robust devices, which can withstand extreme operating conditions (very high temperatures, high pressure etc.). They do not require any embedded electronics and can be implanted in various kinds of (dielectric) structures. Moreover, SAW Sensors of the Reflective Delay Line (R-DL) type have built-in RFID capabilities, which can prove extremely useful for various industrial applications.

Our presentation will start with an overview of CTR R&D activities.

We will then present a short review of SAW RFID Sensors for industrial applications, with a focus on implantable devices like torque sensors, pressure sensors, and temperature sensors. Specific examples of applications in the chemical, automotive and steel industries will be provided.

We will then discuss the potential of SAW RFID Sensors for SHM applications. Existing solutions will be described, as well as possible applications based on existing 2.45GHz R-DL devices. As SAW sensors often fail in operation, due especially to housing failure at high temperature, promising ‘package-less’ solutions will be presented. Here, guided modes that propagate in protective multilayer structures are used, instead of surface waves. Several multilayer configurations have been suggested, simulated and/or tested in the past years. Pros & cons of the different configurations will be discussed.