Wearable Antenna Sensor Based on EBG Structure for Cervical Curvature Monitoring

With the popularization of electronic products, more and more people have cervical spine troubles. This paper proposed an antenna sensor for detecting the bending state of the neck in people’s daily life. The antenna works in the 2.45 GHz industrial, scientific, and medical (ISM) band. When the cervical spine drives the antenna sensor to bend, the resonance frequency of the antenna sensor shifts. Based on this characteristic, the antenna sensor can monitor the bending angle of the cervical spine wirelessly. Placing a ${2}\times {2}$ electromagnetic bandgap (EBG) array between the antenna sensor and the neck reduces the specific absorption rate (SAR) of the human body by about 90% and increases the peak gain from 2.46 dBi to 6.75 dBi. Even if the antenna sensor is bent and deformed greatly, the gain of the antenna sensor remains good. The efficiency of the antenna sensor loaded with the EBG array keep at 65%, and the sensitivity to the bending angle reaches 7.5 MHz/1°. The measured results of the fabricated antenna sensor are in good agreement with the simulated ones. The experimental results show that the proposed antenna sensor is suitable for cervical curvature monitoring.