engleski

Contactless Microenvironment Sensor

The availability of analogue signal inputs on radio-frequency identification circuits is driving new opportunities for contactless sensing. We are developing applications outside of typical cool- chain temperature tracking by designing novel sensors onto custom RFID labels compatible with the ISO15693 smartcard protocol. This poster describes a contactless microenvironment sensor developed for the long-term in-situ and non- destructive monitoring of steel reinforced concrete (RC) structures. The sensor consists of a custom four-point electrode-array interfaced to a high-frequency (HF) RFID tag. The four-point electrode measures the local resistivity of the concrete and a separate on-chip sensor measures the temperature in the concrete microenvironment. The microenvironment sensor could be embedded in concrete cover layers or other bulk aggregate materials such as cement, mortar, sand or soil to a depth of around 50 cm when operated in either passive (batteryless) or semi-passive modes. Multiple sensors may be distributed throughout a structure to cover larger surface areas or for depth profiling. Data on the temperature and resistivity of the microenvironment in the immediate surrounds of each embedded sensor is then gathered with an RFID reader. This data is subsequently correlated to the probable corrosion status of the steel reinforcement bars (rebars), and may be used to estimate when a threshold or limit state might be reached.

contactless sensor; microenvironment monitoring; RFID; concrete corrosion; resistivity

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