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.

Fabrication of Piezo-Resistance Composites Containing Thermoplastic Polyurethane/Hybrid Filler Using 3D Printing

In this study, 3D-printable flexible piezoresistive composites containing various amounts of cilia-like hybrid fillers were developed. In the hybrid fillers, micro-scale Cu particles with a 0D structure may allow them to easily disperse into the flexible TPU matrix. Furthermore, nanoscale multi-walled carbon nanotubes (MWCNTs) with a high aspect ratio, present on the surface of the Cu particles, form an electrical network when the polymer matrix is strained, thus providing good piezoresistive performance as well as good flowability of the composite materials. With an optimal hybrid filler content (17.5 vol.%), the 3D-printed piezoresistive composite exhibits a gauge factor of 6.04, strain range of over 20%, and durability of over 100 cycles. These results highlight the potential applications of piezoresistive pressure sensors for health monitoring, touch sensors, and electronic skin.

Efficient in-depth analysis and optimum design parameter estimation of MEMS capacitive pressure sensor utilizing analytical approach for square diaphragm

Capacitive pressure sensors have become more popular as compared to piezoresistive pressure sensors as they yield superior sensitivity and lesser non-linearity. Efficient analysis for modelling capacitive pressure sensors is thus increasingly becoming more important due to their innumerable use cases. The higher sensitivity of square diaphragm for the same side length in comparison to circular diaphragm makes it ideal for sensor design. In this work, a complete formulation for analysis of capacitive pressure sensor with the square diaphragm in normal and touch mode operation has been presented as these two modes are established operating modes for these sensors. A comprehensive study of sensor parameters like capacitance, diaphragm deflection, capacitive and mechanical sensitivity has been formulated to aid the choice of sensor characteristics. This work also focuses on the method to determine core design parameters for optimal operation. Computationally complex methods have been used in the past for analysis of square diaphragms. In contrast to the finite element system, the analytical technique proposed in this study is less complex and computationally efficient (FEM). The results were computed and simulated using MATLAB.

Wearable Pressure Sensors Based on Carbonized Graphene Coated Waste Paper Aerogel

Graphene is complexed with cellulose fibers to construct 3D aerogels, which is generally considered to be an environmentally friendly and simple strategy to achieve wide sensing, high sensitivity and low detection of wearable piezoresistive pressure sensors. Here, graphene is incorporated into waste paper fibers with cellulose as the main component to prepare graphene coated waste paper aerogel (GWA) using a simple “filtration-oven drying” method under atmospheric pressure. The GWA was further annealed to obtain the carbonized graphene coated waste paper aerogel (C-GWA) to achieve low density and excellent resilience. The result shows that the C-GWA has a rough outer surface due to the 3D structure formed by interpenetrated fibers and the carbon skeleton with wrinkles. The sensor based on GCA shows low density (25mg/cm3), a wide detection range of 0-132 kPa, an ultra-low detection limit of 2.5 Pa (a green bean, ≈ 53.4 mg), and a high sensitivity of 31.6 kPa− 1. In addition, the sensor based on C-GWA with the excellent performance can be used to detect human motions including the pulse of the human body, cheek blowing and bending of human joints. The result indicates that the sensor based on C-GWA shows great potential for wearable electronic products.

Investigation of High Sensitivity Piezoresistive Pressure Sensors for -0.5…+0.5 kPa

The investigation of the pressure sensor chip’s design developed for operation in ultralow differential pressure ranges has been conducted. The optimum geometry of a membrane has been defined using available technological resources. The pressure sensor chip with an area of 6.15х6.15 mm has an average sensitivity S of 34.5 mV/кPa/V at nonlinearity 2KNL = 0.81 %FS and thermal hysteresis up to 0.6 %FS was created. Owing to the chip connection with stop elements, the burst pressure reaches 450 кPa.

Development of High-Sensitivity Piezoresistive Pressure Sensors for -0.5…+0.5 kPa

A mathematical model of an ultrahigh sensitivity piezoresistive chip of a pressure sensor with a range from -0.5 to 0.5 kPa has been developed. The optimum geometrical dimensions of a specific silicon membrane with a combination of rigid islands to ensure a trade-off relationship between sensitivity (Ssamples = 34.5 mV/kPa/V) and nonlinearity (2KNL samples = 0.81 %FS) have been determined. The paper also studies the range of the membrane deflection and makes recommendations on position of stops limiting diaphragm deflection in both directions; the stops allow for increasing burst pressure Pburst up to 450 кPa. The simulated data has been related to that of experimental samples and their comparative analysis showed the relevance of the mathematical model (estimated sensitivity and nonlinearity errors calculated on the basis of average values are 1.5% and 19%, respectively).