Fig 1 - uploaded by Hongpu Li
Content may be subject to copyright.
Source publication
By employing the surface and bulk micro-electro-mechanical system (MEMS) techniques, we design and demonstrate a simple and miniature optical Fabry-Perot interferometric pressure sensor, where the loaded pressure is gauged by measuring the spectrum shift of the reflected optical signal. From the simulation results based on a multiple cavities inter...
Context in source publication
Context 1
... employing the MEMS technology, a variety of optical MEMS pressure sensors based on Fabry-Perot interferometry have recently been proposed and fabricated [1-8]. The major advantages of the optical sensors over the conventional electrical sensors include the immunity to electromagnetic interference, resistance to harsh environment and capability for multiplexing. Fabry-Perot interferometer is an optical component consisting of two partially reflecting parallel mirrors separated by a gap. With this robust structure, one can easily measure a loaded pressure by detecting the changes of the reflected or transmitted optical signals due to the shift of this gap [1, 6-8]. Merits of the MEMS technology is proved in manufacturing the sensing elements with small and definite size. The measured response range, bandwidth, and sensitivity can be flexibly achieved by adjusting the size of sensing elements. In the previous works, different configurations of optical MEMS Fabry-Perot pressure sensors have been proposed, such as the ones using either a corrugated diaphragm [4] or single deeply corrugated diaphragm [5-6] to form the pressure-sensitive element, or the ones by bonding a planar diaphragm directly onto a polished fiber end face [3] or a Pyrex glass [7-8] surface where a hole is drilled for the inserted fiber. However, the high costs of manufacturing instruments as well as the complicated processing techniques are needed. To a certain extent, simplification to the sensing elements and their fabrication processes will be helpful for mass production and commercialization. The purpose of this paper is to present an optical MEMS pressure sensor which is fabricated by using the simplified micromachining techniques. Several methods are employed to simplify the fabrication process. A multiple cavities interference model for this sensor is introduced, which is used to analyze and design the optical sensing elements with composite membrane structures. In addition, the influences of silicon diaphragm thickness on the pressure response range and sensitivity are also analyzed in this paper. As shown in Fig. 1, the pressure-sensing element consists of a glass plate and a silicon diaphragm where a deep cavity is anisotropically etched into the upper surface and a shallow cylindrical cavity is etched into the underside surface. Because the refractive indexes of the optical fiber, glass, air, silicon, and pressure medium are different, the light is coupled into the pressure sensor through optical fiber and reflected by each interface. The light interfered in multiple media is then coupled out of the sensor through the same optical fiber. The width of the air gap varies along with the loaded pressure due to the deflection of the silicon diaphragm. Since there exists a close relation between the width of the air gap and the reflection spectrum, it is expected that one can easily know the loaded pressure by measuring the spectrum ...
Similar publications
In this paper, a novel optical MEMS accelerometer sensor is proposed by using a two-dimensional Photonic Crystal Add-Drop Filter (PCADF) which is relied on a wavelength modulation approach. The proposed optical sensing system consists of a Laser Diode (LD) light source, tunable Add-Drop Filter (ADF) based on Ring Resonator (RR) principal, Photo-Det...
This paper reports patterned nano-crystalline MoS 2 as a sensing element for stress and electromagnetic radiation sensing. Sidewall Transfer Technique (STT) is used to pattern these nano-crystalline MoS 2 sensing structures without using any high-end lithography tool. All these sensing structures are realized on an SOI wafer. Four-point bending met...
The burst of the Internet bubble in 2000 has severely quenched the pace of development in the optical MEMS field. However,
it is now clear that this field is again set to move forward as not only telecommunication but many other industries are benefiting
from its application. We describe in this paper some of our latest achievements in the field, s...
A novel lateral dual-axis a-Si/SiO2 waveguide Bragg grating based quad-beam accelerometer with high-resolution and large linear range has been presented in this paper. The sensor consists of silicon bulk micromachined proof mass suspended by silica beams. Three ridge gratings are positioned on the suspending beam and proof mass to maximize sensitiv...
Citations
... In micro-opto-electro-mechanical system (MOEMS) sensors, the proof mass displacement changes the characteristics of the output light. They use several approaches, such as intensity-based detection, [3,16,19] fiber Bragg grating (FBG) [20,21], and Fabry-Pérot interferometry (FPI) [17,[22][23][24][25][26][27]. An intensity-based optical displacement sensor measures the intensity change of the light and converts it into displacement information. ...
... This research used microtechnology and an FPI. This interferometer has been widely used because of its high sensitivity, low cost, simple structure, and immunity to electromagnetic interference (EMI) [17,[22][23][24][25][26][27]. We used photonics and MEMS because the merging of these technologies helps to overcome problems that are mainly found in EMI conditions, where electronic instrumentation and/or common sensors are either unable to be used or are extremely expensive. ...
The micro-electromechanical system (MEMS) sensors are suitable devices for vibrational analysis in complex systems. The Fabry–Pérot interferometer (FPI) is used due to its high sensitivity and immunity to electromagnetic interference (EMI). Here, we present the design, fabrication, and characterization of a silicon-on-insulator (SOI) MEMS device, which is embedded in a metallic package and connected to an optical fiber. This integrated micro-opto-electro-mechanical system (MOEMS) sensor contains a mass structure and handle layers coupled with four designed springs built on the device layer. An optical reading system using an FPI is used for displacement interrogation with a demodulation technique implemented in LabVIEW®. The results indicate that our designed MOEMS sensor exhibits a main resonant frequency of 1274 Hz with damping ratio of 0.0173 under running conditions up to 7 g, in agreement with the analytical model. Our experimental findings show that our designed and fabricated MOEMS sensor has the potential for engineering application to monitor vibrations under high-electromagnetic environmental conditions.
... Optical fiber MEMS pressure sensors have the characteristics of small volume, light weight, anti-electromagnetic interference, and tolerance to harsh environments [15] and are widely used in biomedicine, environmental monitoring, and other fields [16][17][18]. ...
... When the pressure acts on one end face of the F-P cavity, the cavity length will change, which further causes the wavelength of the F-P cavity to change to realize pressure sensing [19]. The F-P cavity is composed of silicon wafers [15,[20][21][22][23]. When the external temperature changes, the thermal expansion and cold contraction effect of silicon wafers and the influence of residual pressure will lead to changes in the cavity length [22,[24][25][26][27]. ...
... Wu Zhenhai et al. [29] conducted modeling and experimental analysis on the factors influencing the temperature performance of the MEMS pressure sensor and obtained the conclusion that the temperature sensitivity was 0.2333 nm/°C in the ideal model. Ming Li et al. [15] designed a simple and small optical fiber F-P pressure sensor using surface and bulk MEMS technology but did not give a solution to the temperature dependence. Xiaoguang Qi et al. [20] designed an optical fiber F-P pressure sensor with MEMS microcavity structure, which can realize ultra-high pressure detection, and the temperature effect was better than 2.665 × 10 −3 rad/°C . ...
The characteristics of optical fiber MEMS pressure sensors are easily affected by temperature, so effective temperature compensation can improve the accuracy of the sensor. In this paper, the temperature characteristics of optical fiber MEMS pressure sensors are studied, and a temperature compensation method by converting the wavelength is proposed. The influence of target temperature and data point selection on the compensation effect is studied, and the effectiveness of the method is verified by the temperature compensation of sensors before and after aging. When the converted target temperature is 25 °C, the pressure measurement accuracy of the sensor is improved from 1.98% F.S. to 0.38% F.S. within the range of 5–45 and 0–4 MPa. The method proposed in this paper can not only improve the accuracy but also make the regular calibration more operable.
... In the typical transmission structure of optical pressure sensor, the pressure directly forces onto the straight waveguide to modulate the optical signal [11], and then more abundant transmission structures including F-P cavity [12], Bragg grating [13], ring resonator [14], MZI structure [15] and distributed waveguide [16] appear to improve the performance. Several researches have reported the combination of waveguides and graphene as a new transmission structure for modulators [17,18], spectral sensing [19], and biochemical sensing [20]. ...
In this paper, a graphene composite structure based optical absorption pressure sensor is proposed. First, a composite structure which is composed of PDMS micro-pyramid structure, graphene film, and waveguide is introduced. The sensitive mechanism and dynamic working state of the pressure sensor are analyzed continuously. Second, the mapping between the pressure on PDMS and its contact area with the graphene film is deeply analyzed, as well as the optical transmission properties of graphene combined with waveguides, followed by a series of simulations about the optical power output performance facing different pressure conditions. Finally, the designed sensor samples are prepared and a series of performance verification experiments were carried out. The experimental results show that the range of the pressure sensor is 0-870kPa. The sensitivity in the pressure range of 0-100kPa is 2.83×10⁻¹µW/kPa. The experimental results effectively prove that the designed graphene composite structure based optical absorption pressure sensor has high sensitivity and good repeatability, which further verifies the feasibility of the design and analysis method.
... The cavity length can be obtained by applying a fast Fourier transform (FFT) to the acquired reflection spectrum [11][12][13] or by using peak tracing methods [14,15]. The advantages of spectral domain interrogation include large dynamic range, immunity to light intensity fluctuations, and multiparameter sensing capability with a multi-cavity FP interferometric sensor [16][17][18][19]. However, most existing spectral domain interrogation methods are not suitable for high-speed dynamic measurements due to the speed limitation of spectrometers or tunable lasers used in these methods. ...
We report high-speed, large dynamic range spectral domain interrogation of fiber-optic Fabry–Perot (FP) interferometric sensors. An optical interrogation system employing a piezoelectric FP tunable filter and an array of fiber-Bragg gratings for wavelength referencing is developed to acquire the reflection spectrum of FP sensors at a high interrogation speed with a wide wavelength range. A 98 nm wavelength interrogation range was obtained at the resonance frequency of ${\sim}{110}\;{\rm kHz}$ ∼ 110 k H z of the FP tunable filter. At this frequency, the resolution of the FP cavity length measurement was 1.8 nm. To examine the performance of the proposed high-speed spectral domain interrogation scheme, two diaphragm-based fiber-tip FP sensors (a pressure sensor and acoustic sensor) were interrogated. The pressure measurement results show that the high-speed spectral domain interrogation method has the advantages of being robust to light intensity fluctuations and having a much larger dynamic range compared with the conventional intensity-based interrogation method. Moreover, owing to its capability of measuring the absolute FP cavity length, the proposed interrogation system mitigates the sensitivity drift that intensity-based interrogation often suffers from. The acoustic measurement results demonstrate that the high-speed spectral domain interrogation method is capable of high-frequency acoustic measurements of up to 20 kHz. This work will benefit many applications that require high-speed interrogation of fiber-optic FP interferometric sensors.
... This enables obtaining a sensor with all the advantages of fiber-optic sensors, such as high sensitivity, the insensibility to the electromagnetic interference, etc., and the advantages of the micromechanical elements, such as small size and adaptive management ability of the sensor parameters by changing its geometry at the engineering steps. The most widespread fiber-optic sensors are microaccelerometers [4][5][6][7] and pressure sensors [8][9][10]. Previous studies also reported successful implementations of electric voltage sensors [11], chemical sensors [12], acoustic sensors [13]. ...
The paper proposes a technology based on UV-LIGA process for microoptoelectromechanical systems (MOEMS) manufacturing. We used the original combination of materials and technological steps, in which any of the materials does not enter chemical reactions with each other, while all of them are weakly sensitive to the effects of oxygen plasma. This made it suitable for long-term etching in the oxygen plasma at low discharge power with the complete preservation of the original geometry, including small parts. The micromembranes were formed by thermal evaporation of Al. This simplified the technique compared to the classic UV-LIGA and guaranteed high quality and uniformity of the resulting structure. To demonstrate the complete process, a test MOEMS with electrostatic control was manufactured. On one chip, a set of micromembranes was created with different stiffness from 10 nm/V to 100 nm/V and various working ranges from 100 to 300 nm. All membranes have a flat frequency response without resonant peaks in the frequency range 0–200 kHz. The proposed technology potentially enables the manufacture of wide low-height membranes of complex geometry to create microoptic fiber sensors.
... Most DEFPI work has targeted high-sensitivity, low-pressure [3], and acoustic wave [4] applications, although high-pressure sensors have also been achieved [5]. The thickness, material stiffness (i.e., Young's modulus), and diameter of the membrane correlate directly with the pressure sensitivity, operating range, and maximum frequency response of the device [6,7]. Thus, a wide variety of membrane materials have been studied, ranging from graphene [8] to stainless steel [9], among many others. ...
We describe the use of on-chip buckled-dome Fabry–Perot microcavities as pressure sensing elements. These cavities, fabricated by a controlled thin-film buckling process, are inherently sealed and support stable optical modes (finesse ${\gt}{{10}^3}$ > 10 3 ), which are well-suited to coupling by single-mode fibers. Changes in external pressure deflect the buckled upper mirror, leading to changes in resonance wavelengths. Experimental shifts are shown to be in good agreement with theoretical predictions. Sensitivities as large as ${\sim}{1}\;{\rm nm/kPa}$ ∼ 1 n m / k P a , attributable to the low thickness ( ${\lt}{2}\;\unicode{x00B5}{\rm m}$ < 2 µ m ) of the buckled mirror, and resolution ${\sim}{10}\;{\rm Pa}$ ∼ 10 P a are demonstrated. We discuss potential advantages over traditional low-finesse, quasi-planar Fabry–Perot pressure sensors.
... The main drawback of using piezoelectric material is that it is greatly affected by temperature, which can alter its performance. Other common methods to measure pressure include an optical technique [15]. Fabry-Perot interferometry was used to establish the relation between pressure and reflection spectrum shift (in nanometers) [15], The principle of interferometry was applied to measure the pressure of acoustic signal with an optical fiber [16]. ...
... Other common methods to measure pressure include an optical technique [15]. Fabry-Perot interferometry was used to establish the relation between pressure and reflection spectrum shift (in nanometers) [15], The principle of interferometry was applied to measure the pressure of acoustic signal with an optical fiber [16]. Using MEMS technology, a Fabry-Perot interferometer was built directly on the optical fiber to sense pressure [17]. ...
Applying electrostatic levitation force to the initially-closed gap-closing electrodes of our micro-electro-mechanical system (MEMS) creates multi actuation mechanisms, and opens a new world to the MEMS applications. Electrostatic levitation allows us to measure physical quantities, such as air pressure, by exploiting pull-in instability and releasing. The beam starts from a pulled-in position by applying a voltage difference between two gap-closing electrodes. When enough voltage is applied to the side electrodes, the cantilever beam is released. At the release instant, electrostatic forces, restoring force, and surface force are applied to the cantilever. According to the experimental results of this work, the surface interaction force varies as the pressure changes. This work shows that at the release instant, we can correlate the pressure and the interaction force. This idea is exhibited by two mechanisms in this work: a pressure sensor and a pressure switch. Having side electrodes has enabled measuring interaction forces, which was not possible with conventional gap-closing electrodes. The interaction forces are estimated using the experimental data at different pressures. The results show that the interaction force is mostly repulsive and is increased as the pressure is increased. In addition, we found that the potential voltage between the gap-closing electrodes in pulled-in position immensely influences the surface interactions.
... When the sensor is subjected to a force, the width of the cavity in silicon diagram is changed. The pressure value can be obtained by analyzing the relationship between the cavity and reflected spectrum shifts [167]. ...
... These structures can be classified according to the cavity formation, such as intrinsic and extrinsic FPI sensors. The most common extrinsic Fabry-Perot fiber optic structure used for pressure sensing applications employs Micro Electro Mechanical Systems (MEMS) (Abeysinghe et al. 2001;Li et al. 2006;Qi et al. 2019;Wang et al. 2006a, b). The adequate performance of these structures has been widely demonstrated. ...
An experimental study of the interaction between a Mylar® polymer film and a multimode fiber-optic is presented for the simultaneous fiber-optic detection of low-pressure and liquid levels. The junction between the polymer and optical fiber produces an interference spectrum with maximal visibility and free spectral range around 9 dB and 31 nm, respectively. Water pressure, which is controlled by the liquid level, stresses the polymer. As a result, the spectrum wavelength shifts to the blue region, achieving high sensitivities around 2.49 nm/kPa and 24.5 nm/m. The polymeric membrane was analyzed using a finite element model; according to the results, the polymer shows linear stress response. Furthermore, the membrane material is operated below the yielding point. Moreover, the finite analysis provides information about the stress effect over the thickness and the birefringence changes. This sensor exhibits a quadratic polynomial fitting with an adjusted R-squared of 0.9539. The proposed sensing setup offers a cost-effective alternative for liquid level and low-pressure detection.
... Particularly, the fiber-tip FP sensors, by the forming of the FP cavities on the fiber facets, due to the features of simpler structure, more compact size, and versatile to be used, have attracted much more attentions. The fiber tip FP sensors can be formed by attaching a dielectric, metal or polymer film on the fiber facet [6][7][8][9], fabricating an FP structure through micro electro mechanical system (MEMS) processing and then attaching it on a fiber facet [10,11], the writing of a micro FP cavity near the fiber endface through the femtosecond laser micromachining technology [12,13], and many other methods. These fiber tip FP sensors have been proposed for the sensing of various physical, chemical, or biological parameters such as temperature, pressure, pH value, and chemical concentration. ...
A fiber-optic temperature sensor based on fiber tip polystyrene microsphere is proposed. The sensor structure can be formed simply by placing and fixing a polystyrene microsphere on the center of an optical fiber tip. Since polystyrene has a much larger thermal expansivity, the structure can be used for high-sensitive temperature measurement. By the illuminating of the sensor with a broadband light source and through the optical Fabry-Perot interference between the front and back surfaces of the polystyrene microsphere, the optical phase difference (OPD) or wavelength shift can be used for the extraction of temperature. Temperature measurement experiment shows that, using a fiber probe polystyrene microsphere temperature sensor with a spherical diameter of about 91.7 µm, a high OPD-temperature sensitivity of about −0.617 96 nm/°C and a good linearity of 0.991 6 were achieved in a temperature range of 20°C–70°C.
