Elastic transition and pressure sensing in Ti3C2Tx MXene via photothermal actuated nanomechanical resonator

Nanomechanical resonators made of suspended MXene-sensitive membranes can be used to characterize thermodynamic properties. A highly sensitive MXene Fabry-Perot resonant pressure sensor was developed by transferring Ti3C2Tx MXene onto a Transmission electron microscope (TEM) grid with an aperture of 20 μm. The MXene membrane was suspended and clamped on a TEM grid, and its resonance was detected by optical fiber photothermal excitation. To determine the elastic properties of the MXene resonator, the relationship between the resonance response and Young's modulus was analyzed theoretically based on experimental data, and Young's modulus of the MXene-sensitive membrane of the resonator was calculated to be 18 GPa. Subsequently, the measured resonance behavior showed that the sensor reached a maximum resonance frequency of 4.31 MHz over the test range from 0.005 to 100 kPa. It also has a sensitivity of 24.2 kHz/kPa, which is higher than that of common silicon/graphene resonant pressure sensors with sensitivities ranging from 0.1 to 6.9 kHz/kPa. Moreover, the maximum frequency shifts of the resonator at 5 mW, 6 mW, and 7 mW optical power compared to the average frequency of 4.322 MHz, 4.344 MHz, and 4.367 MHz are 0.03%, 0.03%, and 0.04%, with a standard deviation of 1.2 kHz, 1.4 kHz, and 2.1 kHz, respectively. The sensor structure proposed in this paper offers a promising solution for miniaturization and characterization of the elastic properties of pressure sensors using two-dimensional materials as sensitive membranes.