Fabrication, characterization, and simulation of a cantilever-based airflow sensor integrated with optical fiber M. Sadegh Cheri, 1,2 Hamid Latifi, 1,2, * F. Beygi Azar Aghbolagh, 1 O. R. Ranjbar Naeini, 1 Majid Taghavi, 1 and Mohammadamir Ghaderi 1,3 1 Laser & Plasma Research Institute, Shahid Beheshti University, Evin, Tehran 1983963113, Iran 2 Department of Physics, Shahid Beheshti University, Evin, Tehran 1983963113, Iran 3 Present address: Delft University of Technology, Faculty of EEMCS, Department of ME/EI, Mekelweg 4, Delft 2628 CD, The Netherlands *Corresponding author: latifi@sbu.ac.ir Received 23 January 2013; revised 8 April 2013; accepted 13 April 2013; posted 15 April 2013 (Doc. ID 183941); published 10 May 2013 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. © 2013 Optical Society of America OCIS codes: (060.2310) Fiber optics; (120.0280) Remote sensing and sensors. http://dx.doi.org/10.1364/AO.52.003420 1. Introduction Measuring gas flow plays an important role in mechanical engineering, environmental monitoring, industrial process control, biotechnology, and chemi- cal and medical applications. Flow sensing by micro- electromechanical system (MEMS) technologies, have many advantages compared with their conven- tional large-scale counterparts, such as anemome- ters, turbines, Pitot tubes, and so forth [ 1– 7]. MEMS sensors have many advantages including lower power consumption, higher precision, more rapid response, more improved portability, and lower manufacturing cost [ 8– 12]. MEMS-based flow sensors are a good candidate for measuring of gas flow due to the mentioned advan- tages. These sensors are either thermal or nonther- mal. In the thermal type, the gas flow rate is determined by measuring the change in the heat transport capability of the sensing medium caused by its interaction with the airflow. However, thermal airflow sensors have some disadvantages, such as slow response, high power consumption, and low signal level, which limit their application. Moreover, one factor that limits the sensitivity of these sensors is the heat loss from the heating element to the substrate [ 13, 14]. Nonthermal or mechanical flow sensors incorporate a moving mechanical force- sensing structure like a cantilever. The airflow causes a displacement in micro cantilever, which induces a corresponding change in the output of 1559-128X/13/143420-08$15.00/0 © 2013 Optical Society of America 3420 APPLIED OPTICS / Vol. 52, No. 14 / 10 May 2013