Sensitivity Of Piezoresistive Pressure Sensor Research Articles

A diaphragm secondary stress utilization method for increasing the sensitivity of piezoresistive pressure sensors without sacrificing linearity

Piezoresistive pressure sensors with high sensitivity and linearity are critical for aerospace and other industries, however, attempts to improve sensitivity often reduce linearity. Therefore a diaphragm secondary stress utilization method (DSSUM) is proposed, which can significantly increase sensor sensitivity without sacrificing the linearity. The DSSUM realizes the detection of primary and secondary stresses on the diaphragm through the eight-piezoresistor Wheatstone bridge without changing the structure of the diaphragm. A differential pressure sensor with a measurement range of −15 ∼ 15 kPa has been designed and fabricated based on DSSUM. Comparative test results show that DSSUM can increase the sensitivity of the sensor by 50.32 % to 32.35 mV/kPa while maintaining the linearity at 0.031 %F.S. The repeatability of the sensor is 0.02 %FS, the hysteresis is 0.01 %FS, and the zero drift is 0.052 %FS. By using DSSUM, both wide-range and small-range pressure sensors can increase their sensitivity by more than 50 % without impacting linearity. The DSSUM offers a new method for achieving high-performance pressure sensors and holds potential for wide application.

Mechanical buckling assisted formation of 3D conductive composite meso-structure for highly sensitive piezoresistive pressure sensor

With the advancement of robotics and wearable devices related research fields, enhancing the sensitivity of piezoresistive pressure sensor is the first demand of the related research to sense the subtle stimuli. To improve sensitivity, a material tailoring approach using the nature of different materials and an introduction of novel structures made by processing existing materials have been studied. Such latter mechanical exploration has the unique advantage of obtaining performance beyond the nature of the material. This study introduces a 3D meso-structured piezoresistive pressure sensor, which exhibits remarkably improved sensitivity of 450 times compared with that of a conventional 2D sensor, manufactured through simple mechanical buckling assisted 3D structure formation. The principle of sensitivity improvement is related to the developed tensile strain in the sensor and both numerical and experimental analyses show that the maximum principal strain plays a crucial role as a governing parameter to determine the sensitivity. Classical mechanics-based analyses further show that performances can be easily tuned by adjusting its thickness. The present sensor has excellent durability and reliability (stable over 10,000 operating cycles). Consequently, the use of a highly sensitive sensor with a digital twin application is demonstrated for real-time and virtual stress monitoring in a cantilever.

Sensitivity of Piezoresistive Pressure Sensors to Acceleration

The article presents the negative aspects of the influence of static and dynamic acceleration on the accuracy of pressure measurement for a selected type of transmitter. The influence of static accelerations from catalog notes was shown and compared with the tests results for a few selected sensors. The results of research on the influence of dynamic acceleration for various types of its variability for selected converters are presented. Moreover, a method of measurement patented by the authors that uses a complex transducer is shown. The method allows for more accurate measurements on moving objects. The tests were performed based on the proposed method. The obtained results of the influence of acceleration on the classical sensor as well as the construction using the proposed method are shown. The paper presents approximate pressure measurement errors resulting from the influence of acceleration. For example, errors in measuring the speed of an airplane may occur without the proposed method. The last part of the article presents a unique design dedicated to a multi-point pressure measurement system, which uses the presented method of eliminating the influence of accelerations on the pressure measurement.

Analytical modeling to estimate the sensitivity of MEMS technology-based piezoresistive pressure sensor

Design and modeling of microelectromechanical system (MEMS)-based piezoresistive pressure sensor are main requirements to fabricate application-oriented pressure sensor devices for the industry, i.e., nuclear power plants, aerospace and avionics, oil and gas, Internet of Things, wearable electronics and consumer electronics. In this research work, analytical modeling is presented to estimate the overall sensitivity of the MEMS technology-based piezoresistive pressure sensor. The sensitivity of a piezoresistive pressure sensor is estimated using the thin plate theory and the theory of piezoresistivity in silicon. The mechanical responses of a thin plate in terms of deflection and induced stresses are presented and discussed. The effects of geometrical parameters on deflection and induced stresses are analyzed using a ratio of half-edge length with the thickness ( $$a/h$$ ) and a ratio of diaphragm edges ( $$a/b$$ ). These ratio parameters are responsible for the sensitivity of the piezoresistive pressure sensor. Moreover, a comparative assessment is presented for the current model with a model available in the literature. Further, calculations of average stresses are carried out for the piezoresistor geometry of a small rectangular area. Thereafter, a quantitative variation in the calculated sensitivity is presented based on calculation with maximum stress and average stress. The calculated difference in overall sensitivity is found to be 3%. However, a significant reduction in average stresses as compared to maximum induced stresses is obtained as 28% and 36% change for stress X and stress Y, respectively.

Enhancing Piezoresistive Pressure Response Device Sensitivity by Orders of Magnitude

AbstractA bulk material electrode interfacing approach capable of enhancing the sensitivity of piezoresistive pressure sensors with magnitude orders is presented. Metal copper microwires are emplaced between the bulk conductive substrate and an electrode connecting it to the external circuit, replacing commonly used silver paste. These microwires create gaps on the interface between the two materials and increase the initial system resistance. As the applied pressure rises, the contact area between the substrate and microwires increases while the conductive substrate deforms, resulting in overall resistance reduction. With an appropriate setting of microwires, the sensitivity of the piezoresistive pressure sensor can be enhanced up to 106‐fold. The current design is widely adaptable toward different types of materials and allows a pressure operation of up to 931.2 kPa. The results indicate that rather than developing bulk materials, straightforward improvements in the device connecting interface can significantly enhance pressure response sensitivity with magnitude orders.

Design optimization of high pressure and high temperature piezoresistive pressure sensor for high sensitivity

This paper describes a design method for optimizing sensitivity of piezoresistive pressure sensor in high-pressure and high-temperature environment. In order to prove the method, a piezoresistive pressure sensor (HPTSS) is designed. With the purpose of increasing sensitivity and to improve the measurement range, the piezoresistive sensor adopts rectangular membrane and thick film structure. The configuration of piezoresistors is arranged according to the characteristic of the rectangular membrane. The structure and configuration of the sensor chip are analyzed theoretically and simulated by the finite element method. This design enables the sensor chip to operate in high pressure condition (such as 150 MPa) with a high sensitivity and accuracy. The silicon on insulator wafer is selected to guarantee the thermo stability of the sensor chip. In order to optimize the fabrication and improve the yield of production, an electric conduction step is devised. Series of experiments demonstrates a favorable linearity of 0.13% and a high accuracy of 0.48%. And the sensitivity of HTPSS is about six times as high as a conventional square-membrane sensor chip in the experiment. Compared with the square-membrane pressure sensor and current production, the strength of HPTTS lies in sensitivity and measurement. The performance of the HPTSS indicates that it could be an ideal candidate for high-pressure and high-temperature sensing in real application.

FEM Simulation of a Twin-Island Structure Chip in Piezoresistive Pressure Sensor

In this paper a twin-island structure in piezoresistive pressure sensor based on MEMS technology has been presented, and a finite element mechanical model has been developed to simulate the static mechanical behavior of this twin-island structure sensor chip, especially the stress distributions in diaphragm of the sensor chip, which has a vital significance on piezoresistive pressure sensors’ sensitivity. The possible impacts of twin-island’s location and twin-island’s width on the stress distributions, as well as the maximum value of compressive stress and tensile stress, have been investigated based on numerical simulation with Finite Element Method (FEM). The simulation results show that twin-island’s location has great effect on the stress distributions in sensor chips’ diaphragms and the sensitivity of piezoresistive pressure sensors, compared with the twin-island’s width.

The pressfet: an integrated electret-mosfet based pressure sensor

We present a new MOSFET-based pressure sensor, incorporating an air gap that is a function of pressure and a permanently charged dielectric layer (electret) between the gate and bulk of the MOS structure. In this way we obtain a MOSFET with a pre-charged variable gate capacitance. The theory of this sensor and the NMOS-compatible process for its realization are given. We present also the first experimental results on this new sensor. We have determined the characteristics of sensors with outer dimensions of 1 mm × 2 mm × 0.3 mm and measured a maximum sensitivity of about 10 mA/A/100 mm Hg, which is about ten times higher than the sensitivity of piezoresistive pressure sensors with comparable dimensions. Drawbacks of the present sensor design are a relatively high temperature sensitivity and a rather complex fabrication process.