Ultra-sensitive one-dimensional phononic crystals temperature sensor: theoretical optimization

Abstract

Abstract The present study intends to solve the problem of low-temperature sensitivity of most conventional period materials. A solid/solid one-dimensional phononic crystal design is proposed as a pragmatic thermal sensor. Here, each unit cell of the proposed phononic crystal sensor is designed from epoxy and concrete. In this structure, irregularity in layers’ arrangement results in the generation of resonant peaks at the transmission spectrum. The irregularity is introduced to the system by stacking two mirror phononic crystals to form a whole symmetric phononic crystal design. Thermal variations lead to significant changes in Young’s modulus of concrete and epoxy; consequently, transmission spectra and local resonant peaks are shifted as well. Firstly, the band gap changes, and sensor performance were investigated under different conditions such as the incident angle and the number of unit cells to get the optimum parameters. Meanwhile, promising results have been obtained, with increasing the incident angle, the sensitivity increases exponentially till it reaches 1.5 × 103 Hz/°C at an incident angle = 18°. Also, with increasing the temperature from 25 to 100 °C, the sensitivity increases dramatically from 188.8 to 362.4 Hz/°C, respectively. In addition, the largest value of Q-factor was investigated at periodicity number = 4. Moreover, in this regard, the Q-factor has the value of 3708 at 25 °C and it reaches to the value of 896.6 at 100 °C. That is to say, the obtained results may be useful in designing thermal sensors with a high sensitivity value.