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In this letter, we demonstrate a high-temperature dual-resonator Lamb wave tensile strain sensor which can achieve temperature compensation in a wide temperature range and has high strain sensitivities. This sensor consists of two identical AlN-on-SOI Lamb wave resonators (LWRs) adhered on a uniaxial tensile plate, with the wave propagating directions in the two LWRs parallel and perpendicular to the tensile axis, respectively. The most obvious higher-order Lamb wave modes, i.e., the A4, S4, and S5 modes, in the “parallel” LWR present high strain sensitivities of 0.229 ppm/με (196 Hz/με), 0.480 ppm/με (431 Hz/με), and 0.222 ppm/με (205 Hz/με) all with minus signs, whereas in the “perpendicular” LWR, they demonstrate smaller strain sensitivities all with plus signs. The S4 modes in the two LWRs have almost the same temperature coefficients. Based on the experimental results, a generally applicable beat frequency method with these two LWRs is proposed to realize temperature compensation as well as the high-sensitivity strain measurement. [ABSTRACT FROM AUTHOR]

Here, we demonstrate an uncooled, miniaturized, and high resolution infrared (IR) detector based on an aluminum nitride (AlN) film bulk acoustic resonator with dual resonant modes. Due to temperature dependence of the resonance frequency of the resonator and charge carrier generation effect of the AlN piezoelectric material, both the resonant frequency and valley value in reflection coefficient S11 are found responsive to IR irradiation at each resonant mode, thus realizing four IR sensing signal concurrence in a single device. The four sensing signals achieved IR responsivities of 3.32 Hz/nW, 561.21 μdB/nW, 43.17 Hz/nW, and 53.70 μdB/nW, respectively. The second sensing signal even realized a noise equivalent power down to 108 pW/Hz1/2, which is the lowest value among resonant infrared detectors reported in literature studies till now. More importantly, these four sensing signals lie in two separate frequency bands up to GHz, thus enabling the detector to operate normally by the frequency-hopping sensing method when one of the frequency bands suffers from strong electromagnetic interference. The presented device shows a great potential for ultra-sensitive and anti-interference infrared detection in civilian and military fields. [ABSTRACT FROM AUTHOR]

A piezoelectric AlN-on-SOI structured MEMS Lamb wave resonator (LWR) is presented for high-temperature strain measurement. The LWR has a composite membrane of a 1 μm thick AlN film and a 30 μm thick device silicon layer. The excited acoustic waves include Rayleigh wave and Lamb waves. A tensile strain sensor has been prepared with one LWR mounted on a uniaxial tensile plate, and its temperature characteristics from 15.4°C to 250°C and tensile strain behaviors from 0 με to 400 με of Rayleigh wave and S4 mode Lamb wave were tested. The temperature test verifies the adaptability of the tensile strain sensor to temperature up to 250°C, and S4 mode Lamb wave and Rayleigh wave represent almost the same temperature characteristics. The strain test demonstrates that S4 mode Lamb wave shows much higher strain sensitivity (-0.48 ppm/με) than Rayleigh wave (0.05 ppm/με) and confirms its advantage of strain sensitivity. Finally, for this one-LWR strain sensor, a method of beat frequency between S4 mode Lamb wave and Rayleigh wave is proposed for temperature compensation and high-sensitivity strain readout. [ABSTRACT FROM AUTHOR]