In this paper, we present the fabrication and packaging of a cantilever-based airflow sensor integrated with optical fiber. The sensor consists of a micro Fabry-Perot (FP) cavity including a fiber and a micro cantilever that is fabricated using the photolithography method. Airflow causes a small deflection of the micro cantilever and changes the cavity length of the FP, which makes the fringe shift. The pressure distribution and velocity streamlines across the cantilever resulted from the airflow in the channel have been simulated by the finite element method. The experimental results demonstrate that the sensor has a linear sensitivity of 190 [fringe shift (pm)] per (l / min) and a minimum detectable airflow change of 0.05 l∕min.

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In this paper, a closed-loop micro-opto-electro-mechanical system (MOEMS) accelerometer based on the Fabry-Pérot (FP) interferometer is presented. The FP cavity is formed between the end of a cleaved single-mode optical fiber and the cross-section of a proof mass (PM) which is suspended by four U-shaped springs. The applied acceleration tends to move the PM in the opposite direction. The arrays of fixed and movable comb fingers produce an electrostatic force which keeps the PM in its resting position. The voltage that can provide this electrostatic force is considered as the output of the sensor. Using a closed-loop detection method it is possible to increase the measurement range without losing the resolution. The proposed sensor is fabricated on a silicon-on-insulator wafer using the bulk micromachining method. The results of the sensor characterization show that the accelerometer has a linear response in the range of ±5 g. In the closed-loop mode, the sensitivity and bias instability of the sensor are 1.16 V/g and 40 µg, respectively.

A coarse-to-fine optical microelectromechanical systems (MEMS) accelerometer based on the Fabry–Pérot (FP) interferometer is proposed. The mechanical structure consists of a proof mass that is suspended by four L-shaped springs. The deflection of the proof mass due to the applied acceleration is detected using two FP cavities that comprise the system’s optical system. Using coarse-to-fine measurement and the dual wavelength method simultaneously increases the sensitivity of the accelerometer as well as the linear measurement range. The optical simulation shows that the sensitivity of the proposed device is 10 times as high as that of a similar optical MEMS accelerometer with one FP cavity. In addition, the proposed optical system is insensitive to the displacements of the proof mass in the orthogonal directions, which considerably reduced the cross-axis sensitivity. The minimum feature size of the structure is 15 µm and the optical signal is conducted completely through the optical fibers, facilitating the device fabrication. Here are the results of the simulation: mechanical sensitivity of 190 nm/g, optical sensitivity of 8 nm/g, linear measurement of ± 5 g , and first resonance frequency of 1141 Hz.

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