Wireless Strain Sensors Using Electromagnetic Resonators

The concept of wireless passive strain sensors has been introduced in the last few years for applications such as structural health monitoring. This study investigates the use of circular microstrip patch antenna (CMPA) sensors for wireless passive measurement of strain. The strain induced in an aluminium plate was measured wirelessly up to 5 cm away from the sensor using a CMPA made from commercial FR4 substrate, and at a distance up to 20 cm using a CMPA made from Rogers® RT/duroid 6010™. These results show the substrate of antennas is one of the factors affecting the interrogation distance. The interrogation distance between the sensor and the patch antenna was improved significantly using the Rogers® substrate.