Flexible multimode antenna sensor with strain and humidity sensing capability for structural health monitoring

Sensor, the device to detect certain information and convert into corresponding output signals, is of key importance to structural health monitoring (SHM) system. Compared with the traditional sensor, antenna sensor can reduce the size of sensor system and avoid the peripheral circuits, but there are still many challenges in the research of antenna sensors, such as low sensitivity and single sensing function. Here, a dipole antenna responsive to the strain and humidity is proposed. The dipole antenna is prepared by an ordinary office inkjet printer, besides, the capabilities of proposed dipole antenna to sensing the strain and humidity were verified by experiments, however, the effect of temperature is negligible within 25–45 °C. The sensitivities of antenna sensor to sensing applied strain and humidity are − 24.03 kHz/με (−7.63 ppm/με), − 12.38 MHz/%RH (−2123 ppm/%RH). BP network trained with the experimental data can be well used to decouple of the humidity and strain signal response. The antenna sensor proposed in the study is cost-effective and possesses the excellent strain and humidity sensing ability, which provides a new possibility for the sensors of SHM systems.