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Remote pressure monitoring is of particular importance in medical and environmental applications as it is less labour intensive, safer and offers peace of mind to the general public. To meet this demand, a prototype system has been developed and used to evaluate thick-film pressure sensors with an oxide dielectric layer. The circuit is based on the...
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Context 1
... test the response of the thick-film pressure sensors an effi- cient wireless interface, transmitter, and receiver circuit was de- veloped [26]. A block diagram of the system is shown in Fig. 2. The most important feature of the sensor interface circuit is an integrated capacitance to frequency converter. This connects the device to the telemetry subsystem. The sensor capacitance is first converted to a frequency using a low power TLC556 dual CMOS timer operating in an astable configuration. The output frequency can be ...
Context 2
... was found that for TiO , CeO , and MgO, the change in capacitance with time was less than 5%. The capacitance of the MgO sample fluctuated between increasing and then de- creasing with time. This may be due to the uneven nature of the thick-film, as can be seen in Fig. 2. In addition, the Nb O interdigitated capacitor was extremely unstable, with the capac- itance dropping by 10 pF in the first 2 h. It is thought that the stability of this material could be further improved by mixing it with another oxide, as discussed previously. However, as in the case of a V O -CeO thin-film strain gauge, the ...
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Citations
... Our method exploits the concept of fringing fields set by a coplanar pair of electrodes. Planar capacitors can take many different shapes and forms like interdigitated (comb fingers), rectangular or circular spirals etc. Charles Ezeoru [17], Jeung Sang Go [16], Khalil I. Arshak [19] used the interdigitated electrodes while Yu Gong [20] and Tianming Chen [21] used spiral electrodes. Whichever form the planar capacitor takes, the common key parameter is the dimension of the gap along the interfacial line between the two electrodes. ...
This paper describes the development of an array of coplanar capacitive sensors applied to marine icing. Current atmospheric icing monitoring systems consider single phase conditions in their operation. Marine icing conditions present a unique environment where the liquid water phase effects cannot be neglected and require a novel approach. We have conducted an initial proof of concept and propose a new icing monitoring system which can distinguish between the individual phases. A numerical model confirmed our initial hypothesis of the system’s ability to discriminate the multiphase domains based on the array of geometrically dissimilar capacitive sensors. In addition, we also developed a novel experimental technique based on a comparative study under constant conditions to eliminate the need for an independent ice accretion monitoring system normally required in sensor development. The new approach promises a better characteristic in marine icing monitoring systems or in similar applications where multiphase dielectric is present.
... are used in various fields such as robotics, prosthetics and other wearable systems [11]- [13]. ...
Sensitivity and linearity are important performance metrics of flexible sensors in application. An effective approach towards improving the performance of capacitive pressure sensors (CPS) is the appropriate design of the microstructure of the dielectric layer. Using the finite element modeling in an integration of Abaqus and COMSOL Multiphysics, we propose a methodology to simulate the deformation and capacitance responses of CPS upon external pressure; the numerical results agree well with experimental data. With the attempt to improve the performance of widely used pyramidal and cylindrical microstructure-based CPS, the effects of microstructure geometric parameters and mechanical property of materials such as the elastic modulus, length of hemline, sidewall angle, height and size on the pressure response were investigated, and the sensitivity and nonlinear error were also analyzed. It has been found that the sensitivity and linearity are more sensitive to elastic modulus, and less sensitive to height. With the same sensitivity, the cylinders-based CPS have higher linearity, while the pyramids-based CPS have larger pressure measuring range. The obtained results could provide reference information for the design of CPS with improved application characteristics.
... A robust wireless pressure monitoring system is needed which can reliably work in an unfavorable environment. The development and characterization of some of the wireless monitoring systems have been reported for wirelessly monitoring the parameters of a process, for example, oil-well monitoring system [1], roof wind pressure monitoring system during hurricanes [2], a remotely powered sensing system for measuring absolute pressure, temperature, and relative humidity [3], continuously monitoring sensor resonance frequency variation [4], pressure measurement system for evaluating sensitivity of thick-film oxide materials [5], long-term structural (concrete, asphalt) monitoring system [6], mobile wireless network technology to monitor pipes for water provisioning [7], containment cooling fans' health and performance monitoring in a nuclear power plant [8], etc. Low-power wireless technologies such as Bluetooth or ZigBee have been mostly used for wirelessly measuring some parameters in a process. This results in a relatively expensive system because it is not based on indigenously developed RF components. ...
This article reports the development and characterization of a robust RF transceiver system for wireless monitoring of the pressure variation in a gas pipeline installed in an industry. Proposed system consists of a monolithic silicon pressure sensor for converting applied pressure information to a DC voltage output, a varactor-based voltage controlled oscillator (VCO) for converting DC voltages to RF signal, a power amplifier for amplifying the transmitting RF signal, and two wideband microstip fed filtering antennas used in transmitter and receiver modules. Transmitting antenna is used for radiating the selected RF signal (conditioned pressure information) while reflecting the undesired harmonics. Filtering antenna (Filtenna) at the receiver side is used to detect the desired RF signal while filtering out the undesired signal. Operating frequency band of proposed wireless pressure monitoring system is 2.2565–2.5804 GHz covering lower ISM band (2.4–2.5 GHz). As a proof of concept, experiment has been performed for monitoring of a pressure variation in the range 0–50 kPa and for a distance of 2 m between transmitting and receiving antennas. The measured pressure sensitivity of the proposed gas pressure monitoring system is 6.4786 MHz/kPa with a good linearity response. Calibration curve and curve fitting equations are provided for evaluating the pressure variation in a gas pipeline by detecting the received RF signal at the receiver end. Proposed system can be used for wirelessly monitoring the pressure of a gas pipeline installed in an industry. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2237–2242, 2016
... After the first monolithic capacitive pressure sensor was designed for medical-research applications in 1980 [13], silicon solution tablets technology and etch-stop technique were put forward to make the capacitive sensor [14]. Afterwards, the CPS with different microstructures had been deeply studied due to the introduction of MEMS (microelectromechanical systems) technology [15][16][17][18]. Ji et al. [19] made the capacitive pressure sensor by a combination of a standard CMOS (Complementary Metal Oxide Semiconductors) process and bulk micromachining technology. ...
In order to investigate the interfacial tuning mechanism of electronic skin (
e
-skin), several models of the capacitive pressure sensors (CPS) with different microstructures and several sizes of microstructures are constructed through finite element analysis method. The simulative pressure response, the sensitivity, and the linearity of the designed CPS show that the sensor with micropyramids has the best performance in all the designed models. The corresponding theoretically predicted sensitivity is as high as 6.3 × 10
−7
fF/Pa, which is about 49 times higher than that without any microstructure. Additionally, these further simulative results show that the smaller the ratios of
L
/
H
of pyramid, the better the sensitivity but the worse the linearity. When the ratio of
L
/
H
of pyramid is about
2
, the sensitivity and the linearity could reach a balance point. The simulative results evidently provide the important theoretically directive significance for the further development of
e
-skin.
... Micro pressure sensors are widely applied in automotive, biomedical and various industries. Pressure sensors fabricated by MEMS technology have the benefits of small size, low cost and high performance [1] [2]. The excellent mechanical properties of silicon combined with the fabrication techniques of integrated circuits opened new applications for micromechanical pressure sensors in the past years [3]. ...
Capacitive Pressure sensors have taken over Piezoresistive sensors because of its lower power consumption, low noise and low temperature sensitivity. The sensor sensitivity and range can be further improved by using a variety of designs for the diaphragm. Bossed diaphragm membranes are one among such design which improve the central deflection sensitivity by compensating the back pressure. This paper proposes a segmented boss structure for the sensor diaphragm which not only improves the sensitivity but also the range of operation which was a limiting factor and solve the trade off
... Continuous Pressure monitoring for a long time was considered as a herculean task and moreover it was not even imaginable about a microdevice performing this task.The invention of micromachining process and MEMS technology paved the way for making the unimaginable things possible.Micro pressure sensors are widely applied in automotive, biomedical and various industries.Pressure sensors fabricated by MEMS technology have the benefits of small size,low cost and high performance [1] [2].The excellent mechanical properties of silicon combined with the fabrication techniques of integrated circuits opened new applications for micromechanical pressure sensors in the past years [3]. Many of the MEMS pressure sensors used Piezoresistive transduction meachanism but they are temperature dependent. ...
Capacitive pressure sensors can be used for touch mode applications with pressure ranging from 0.05 MPa to 2 MPa. This paper provides the information about the variation in dynamic range of a MEMS capacitive pressure sensor when its sensitivity is improved. The shape of the capacitive pressure sensor diaphragm is changed from normal flat diaphragm to a centre bossed structure and was found that Bossed diaphragm membranes improves the central deflection sensitivity but the range was limited. MEMS Capacitive pressure sensor with normal diaphragm and diaphragm with centre boss structure is designed and analysed using multiphysics tool and it is found that while the sensitivity is increased by 0.92µm/KPa but the range is reduced by 20KPa for the bossed diaphragm.
... Self-energizing of the sensor is essential as currently no energy storage is available to supply the sensors in a 24/7 manner over several months. [14][15][16] Furthermore, battery storage consumes valuable space within the mold and consequently reduces the advantages of a wireless sensor system. The self-energized sensor converts energy from the melt pressure during injection phase into electrical energy by compressing a piezo stack. ...
Wireless sensing technology for injection molding is of increasing interest in literature. Recently, a purely mechanical in-mold sensor for melt front detection was introduced. The sensor system is based on building resonant structures into the mold which are excited by the passing melt front generating structure-borne sound, from which the melt front position is derived. A big advantage of this system is the possibility to implement a plurality of resonant structures while just having one receiver. One important aspect is the need to separate and assign the recorded impinging sounds. A novel algebraic approach was introduced separating the resonant structures by reference to their oscillatory behavior. In this article, measurement results for over 450 injection molding cycles are given proving functionality of the separation process. In addition, it is shown that the melt front detection is reliable and robust when comparing it with results obtained by cavity temperature sensors.
... Micro pressure sensors are widely applied in automotive, biomedical, space, military and various industrial applications. Pressure sensors fabricated by MEMS technology have the benefits of small size, low cost and high performance [3]. Capacitive pressure sensors provide very high pressure sensitivity, low noise and low temperature sensitivity and preferred in many high performance applications. ...
Employing the MEMS technology, high sensitivities and resolutions have been achieved. Capacitive sensing uses the diaphragm deformation-induced capacitance change. In this paper, the design and simulation of conventional slotted and touch mode MEMS capacitive pressure sensor is proposed. The designed sensors are composed of a polysilicon diaphragm that deflects due to pressure applied over it, is accounted for modeling. The simulation results shows that the slotted MEMS capacitive pressure sensor achieves good sensitivity where as the touch mode MEMS capacitive pressure sensor achieves good linearity and large operating pressure range. The proposed MEMS capacitive pressure sensor demonstrated with diaphragm of side length 20 μm, gap depth 2 m is being modelled. The sensor exhibit a linear response for the pressure applied between 0 to 50 MPa. The simulation is carried out for different types of MEMS capacitive pressure sensor using COMSOL Multiphysics.
... Micro pressure sensors are widely applied in automotive, biomedical, space, military and various industrial applications. Pressure sensors fabricated by MEMS technology have the benefits of small size, low cost and high performance [4] [5]. MEMS are systems of small size, light weight, enhanced performance and reliability finding widest of applications. ...
MEMS(Micro-ElectroMechanical Systems) pressure sensors are designed to operate in linear range and presently the most widely used devices. MEMS pressure sensors have gained popularity in automotive, biomedical and industrial applications. In this paper, the design and simulation of capacitive, piezoelectric and piezoresistive MEMS pressure sensors are proposed. The piezoelectric sensor is composed of Lead Zirconate Titanate(PZT-5A), piezoresistive pressure sensor is composed of n-Silicon(single-crystal, lightly doped) and p-Silicon(single-crystal, lightly doped), the capacitive pressure sensor is composed of SiC(6H) these pressure sensors deflects due to applied pressure from 0 to 2MPa over it are accounted. The modelling and simulation is carried out for different MEMS
... 1,2 Current challenges include the miniaturization and integration of reliable electronic sensors and actuators into PDMS-based chips; 3,4 microfluidic applications demand pressure sensors which are indispensable in control 5,6 and actuation 7 of microfluidic systems. While existing well developed microfluidic sensors are fabricated on silicon, silica, and glass substrates, [8][9][10][11][12] the complex fabrication process, strict fabrication-environmental requirements, the tenuous bonding to PDMS, as well as the hardness and fragility of substrates diminish the advantages of PDMS chips. Moreover, the issue of opacity introduces another element of difficulty into optical monitoring of microfluidic conditions. ...
A novel microfluidic pressure sensor which can be fully integrated into polydimethylsiloxane (PDMS) is reported. The sensor produces electrical signals directly. We integrated PDMS-based conductive composites into a 30 mum thick membrane and bonded it to the microchannel side wall. The response time of the sensor is approximately 100 ms and can work within a pressure range as wide as 0-100 kPa. The resolution of this micropressure sensor is generally 0.1 kPa but can be increased to 0.01 kPa at high pressures as a result of the quadratic relationship between resistance and pressure. The PDMS-based nature of the sensor ensures its perfect bonding with PDMS chips, and the standard photolithographic process of the sensor allows one-time fabrication of three dimensional structures or even microsensor arrays. The theoretical calculations are in good agreement with experimental observations.
