To avoid interference from unexpected background noises and obtain high fidelity voice signal, acoustic sensors with high sensitivity, flat frequency response, and high signal-to-noise ratio (SNR) are urgently needed for voice recognition. Graphene-oxide (GO) has received extensive attention due to its advantages of controllable thickness and high fracture strength. However, low mechanical sensitivity (S_M) introduced by undesirable initial stress limits the performance of GO material in the field of voice recognition. To alleviate the aforementioned issue, GO diaphragm with annular corrugations is proposed. By means of the reusable copper mold machined by picosecond laser, the fabrication and transfer of corrugated GO diaphragm are realized, thus achieving a Fabry–Perot (F–P) acoustic sensor. Benefitting from the structural advantage of the corrugated GO diaphragm, our F–P acoustic sensor exhibits high S_M (43.70 nm/Pa@17 kHz), flat frequency response (−3.2 to 3.7 dB within 300–3500 Hz), and high SNR (76.66 dB@1 kHz). In addition, further acoustic measurements also demonstrate other merits, including an excellent frequency detection resolution (0.01 Hz) and high time stability (output relative variation less than 6.7% for 90 min). Given the merits presented before, the fabricated F–P acoustic sensor with corrugated GO diaphragm can serve as a high-fidelity platform for acoustic detection and voice recognition. In conjunction with the deep residual learning framework, high recognition accuracy of 98.4% is achieved by training and testing the data recorded by the fabricated F–P acoustic sensor.

Regarding the dependence of the treatment of removing polymethyl methacrylate (PMMA) from graphene upon the prestress in the film, two typical PMMA removal methods including acetone-vaporing and high-temperature annealing were investigated based on the opto-mechanical behaviors of the developed optical fiber Fabry-Perot (F-P) resonant sensor with a 125-μm diameter and ~10-layer-thickness graphene diaphragm. The measured resonant responses showed that the F-P sensor via annealing process exhibited the resonant frequency of 481kHz and quality factor of 1034 at ~2 Pa and room temperature, which are respectively 2.5 times and 33 times larger than the acetone-treated sensor. Moreover, the former achieved a high sensitivity of 110.4 kHz/kPa in the tested range of 2Pa–2.5kPa, apparently superior to the sensitivity of 16.2kHz/kPa obtained in the latter. However, the time drift of resonant frequency also mostly tended to occur in the annealed sensor, thereby shedding light on the opto-mechanical characteristics of graphene-based F-P resonant sensors, along with an optimized optical excitation and detection scheme.