State-of-the-art and recent developments in micro/nanoscale pressure sensors for smart wearable devices and health monitoring systems

Small-sized, low-cost, and high-sensitivity sensors are required for pressure-sensing applications because of their critical role in consumer electronics, automotive applications, and industrial environments. Thus, micro/nanoscale pressure sensors based on micro/nanofabrication and micro/nanoelectromechanical system technologies have emerged as a promising class of pressure sensors on account of their remarkable miniaturization and performance. These sensors have recently been developed to feature multifunctionality and applicability to novel scenarios, such as smart wearable devices and health monitoring systems. In this review, we summarize the major sensing principles used in micro/nanoscale pressure sensors and discuss recent progress in the development of four major categories of these sensors, namely, novel material-based, flexible, implantable, and selfpowered pressure sensors.     

碳化硅高温压力传感器的研究进展与展望

碳化硅材料由于其优良的电学、机械和化学特性,在开发适用于高温恶劣环境下的压力传感器等领域,有着广阔的应用前景,逐渐为人们所重视。简单介绍了碳化硅的材料特性,阐述了国外碳化硅高温压力传感器的最新发展成果,比较了电容式、压阻式和光学结构压力传感器的结构、特点,总结了我国碳化硅压力传感器发展问题与挑战。     

Thin-film nano- and micro-electromechanical systems – the basis of contemporary and future pressure sensors for rocket and aviation engineering

Ways of improving information converters are considered, in particular, primary information converters (sensors). Problems are described that arise during the use of sensors in space rocket and aviation engineering. Designs are presented for thin-film nano- and micro-electromechanical systems that are the basis of contemporary and future tensoresistive pressure sensors. Areas of research are determined with the aim of minimizing the effect of critical destabilizing factors (temperature, vibration) within these systems and pressure sensors based upon them.     

Low Pressure Piezoresistive Sensors for Medical Electronics Applications

Piezoresistive pressure sensors are being widely used for various industrial applications, such as in automobiles and process control. But conventional MEMS piezoresistive pressure sensors possess low sensitivity in the lower pressure range for biomedical applications. Alternative structures of MEMS pressure sensors include the use of bossed diaphragms and nanocrystalline piezoresistors. In this paper, four different diaphragm structures—flat diaphragm, standard bossed diaphragm, complementary bossed diaphragm, and nanocrystalline porous silicon-silicon composite diaphragm—have been analyzed in terms of sensitivity and nonlinearity.     

Kalibrierung von Überdruck‐ und Unterdruck‐Messgeräten

Calibration of manometers for gauge pressure Various applications require the measurement of small gauge pressures relative to atmospheric pressure. For this purpose, nowadays electronic sensors are commonly used which are easy to use and which offer good resolution. For reliable pressure readings, these sensors require adjustment and calibration. The accurate calibration of the sensors is a metrological challenge. The present article describes some exploring investigations of calibration methods employing modern equipment and gives some values of the achievable accuracy.     

The potential of microacoustic SAW- and BAW-based sensors for automotive applications - a review

In recent years, sensors and sensor systems have gained increasing importance for automotive electronics. In this paper, the suitability and the perspectives in the application of microacoustic surface- and bulk-acoustic-wave sensors in the fields of angular rate sensors, pressure sensors, wireless sensor readout, and liquid sensors are discussed.     

提高膜片式F-P腔光纤压力传感器灵敏度的试验研究

膜片式F-P腔光纤压力传感器是基于法布里-珀罗干涉原理,采用微电子机械系统(MEMS)技术加工而成。在实际应用中,不同的测试环境对传感器灵敏度的要求各不相同,如果针对不同灵敏度,分别采用MEMS工艺批量化生产,则会造成生产成本过高,经济化效益降低。本文利用湿法腐蚀的方法对传感器进行膜片减薄试验,在一定范围内提高了传感器的压力灵敏度,从而满足了不同的测试需求。膜片减薄后,传感器的灵敏度可达34.2 nm/kPa,压力标定曲线的线性度为0.9997,传感器的非线性误差为0.05%,能够实现0~120 kPa(绝压)范围内压力的准确测量。     

碳纳米管压力传感器研究进展

碳纳米管因其独特而优异的电学、力学、热学、化学及电子特性等在很多领域上展现应用的潜力,而近年来碳纳米管在压力传感器方面的应用成为研究热点之一.本文综述了碳纳米管压力传感器的基本原理以及研究进展,并对不同类型的碳纳米管压力传感器进行了比较.     

A Unified Series of High-Precision Pressure Sensors for Automatic Regulation and Monitoring Systems

A number of high-precision pressure sensors for automatic regulation and monitoring systems are presented. The design-technological principles used in the sensors, which ensure their operating capability under severe operating conditions, are considered. A comparative analysis of the technical level of the sensors and their foreign analogs is given.     

Overview of automotive sensors

An up-to-date review paper on automotive sensors is presented. Attention is focused on sensors used in production automotive systems. The primary sensor technologies in use today are reviewed and are classified according to their three major areas of automotive systems application-powertrain, chassis, and body. This subject is extensive. As described in this paper, for use in automotive systems, there are six types of rotational motion sensors, four types of pressure sensors, five types of position sensors, and three types of temperature sensors. Additionally, two types of mass air flow sensors, five types of exhaust gas oxygen sensors, one type of engine knock sensor, four types of linear acceleration sensors, four types of angular-rate sensors, four types of occupant comfort/convenience sensors, two types of near-distance obstacle detection sensors, four types of far-distance obstacle detection sensors, and and ten types of emerging, state-of the-art, sensor technologies are identified     

Investigation and application of the frustrated-total-internal-reflection phenomenon in optical fibers

A detailed investigation of the frustrated-total-internal-reflection (FTIR) phenomenon in silica-glass-based optical fibers and its application to simple intensity-modulated strain and pressure sensors is presented. Such sensors may be readily fabricated with silica-based fibers and can be easily modified with sapphire fibers for high-temperature industrial applications where conventional silica-based fiber sensors are not feasible. We present the all-fiber FTIR sensor and show good correlation between theory and experiment. We also present results for the design and implementation of a prototype FTIR-based fiber pressure sensor.     

Investigation of the errors of attenuator-type fiber-optic pressure sensors

The errors of attenuator-type fiber-optic pressure sensors are investigated. The sources of errors of these sensors are analyzed and methods of reducing them by construction-technological solutions at the design stage are proposed.     

Pressure Measurement and Traceability at NIS- Egypt

Pressure sensors, transmitters and transducers are widely used for measuring and controlling the pressure. Tracing of measurement of such pressure sensing instrumentation is very important in many industrial applications. Calibrations of pressure instruments with acceptable uncertainty tracing to the SI units are required. This study aims to study the propagation of uncertainty from SI units through primary standard piston cylinder assembly (PCA) up to 500 MPa. The hierarchy of pressure measurements at NIS is based on using large effective area PCA in defining the pressure of 1 MPa. Primary standard PCA characterization and evaluation are presented then transferring the obtained results to other pressure traceability level is described. Calculation and propagation of uncertainty starting from primary standard to digital pressure gauges, digital pressure calibrators, pressure sensors and pressure transducers were investigated.     

Fabrication and Characterization of Single-Layer Textile-Based Flexible Pressure Sensors for Smart Wearable Electronics Applications

Textile-based sensors have been widely studied for wearable monitoring. The sensor systems demand a large sensing area, flexibility, and scalable fabrication method. Herein, single-layer piezoresistive sensors are developed by a machine stitching technique using metallic and graphene nanoplatelets-coated conductive threads and fabrics. The pressure-sensing mechanism is based on measuring the electrical resistance due to the change in the contact area between the conductive thread and fabric as pressure on the sensor varies. The single-layer sensor design provides flexibility and overcomes the physical drift of the sensor during human activities, which enhances wearability and performance. The coated textiles are characterized by scanning electron microscopy and Fourier-transform infrared spectroscopy. Physical and electromechanical tests are performed on the sensors to evaluate their wearability and sensing performance. The sensors exhibit a wide working range of up to 100 kPa and good sensitivity with excellent durability against repeated mechanical deformations. The application potential of the sensors in real-time monitoring is demonstrated by embedding them into clothing as a wearable device. Moreover, the effectiveness of the sensors is tested for posture correction. This article suggests a novel technique to fabricate durable, flexible, and highly efficient pressure sensors for smart wearable applications.     

Self-powered pressure sensor for ultra-wide range pressure detection

The next generation of sensors should be self-powered,maintenance-free,precise,and have wide-ranging sensing abilities.Despite extensive research and development in the field of pressure sensors,the sensitivity of most pressure sensors declines significantly at higher pressures,such that they are not able to detect a wide range of pressures with a uniformly high sensitivity.In this work,we demonstrate a single-electrode triboelectric pressure sensor,which can detect a wide range of pressures from 0.05 to 600 kPa with a high degree of sensitivity across the entire range by utilizing the synergistic effects of the piezoelectric polarization and triboelectric surface charges of self-polarized polyvinyldifluoride-trifluoroethylene (P(VDF-TrFE)) sponge.Taking into account both this wide pressure range and the sensitivity,this device exhibits the best performance relative to that of previously reported self-powered pressure sensors.This achievement facilitates wide-range pressure detection for a broad spectrum of applications,ranging from simple human touch,sensor networks,smart robotics,and sports applications,thus paving the way forward for the realization of next-generation sensing devices.Moreover,this work addresses the critical issue of saturation pressure in triboelectric nanogenerators and provides insights into the role of the surface charge on a piezoelectric polymer when used in a triboelectric nanogenerator.     

压电式压力传感器动态特性补偿技术研究

针对近爆区冲击波压力测试中压电式压力传感器因动态特性不佳造成信号畸变之问题,通过激波管动态校准试验,分析传感器动态特性;对造成动态测试误差的主要因素,利用动态补偿技术设计数字补偿滤波器,对传感器爆炸信号进行补偿处理。结果表明,该方法能有效减小动态测试误差、提高近爆区冲击波压力测试精度。     

Coherence-multiplexed fiber-optic sensor systems for measurements of pressure and temperature changes

A digital demodulation method for read-out of phase changes induced in coherence-multiplexed sensors based on highly birefringent fibers is described. The method employs the fringe counting principle and enables registration of the phase shifts simultaneously induced in two multiplexed sensors with a maximum frequency of 10 kHz and resolution of 1/4 of the interference fringe. The performance of three multiplexed systems interrogated using the proposed detection method is investigated. The first system is composed of two serial multiplexed sensors serving for measurements of pressure and temperature changes in the same location, while the two other systems are composed of two parallel or serial multiplexed temperature-compensated sensors serving for pressure measurements at different locations.     

Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring

Flexible pressure sensors have many potential applications in wearable electronics, robotics, health monitoring, and more. In particular, liquid‐metal‐based sensors are especially promising as they can undergo strains of over 200% without failure. However, current liquid‐metal‐based strain sensors are incapable of resolving small pressure changes in the few kPa range, making them unsuitable for applications such as heart‐rate monitoring, which require a much lower pressure detection resolution. In this paper, a microfluidic tactile diaphragm pressure sensor based on embedded Galinstan microchannels (70 µm width × 70 µm height) capable of resolving sub‐50 Pa changes in pressure with sub‐100 Pa detection limits and a response time of 90 ms is demonstrated. An embedded equivalent Wheatstone bridge circuit makes the most of tangential and radial strain fields, leading to high sensitivities of a 0.0835 kPa^?1 change in output voltage. The Wheatstone bridge also provides temperature self‐compensation, allowing for operation in the range of 20–50 °C. As examples of potential applications, a polydimethylsiloxane (PDMS) wristband with an embedded microfluidic diaphragm pressure sensor capable of real‐time pulse monitoring and a PDMS glove with multiple embedded sensors to provide comprehensive tactile feedback of a human hand when touching or holding objects are demonstrated.     

Embedded micromachined fiber-optic Fabry-Perot pressure sensors in aerodynamics applications

Small size, high bandwidth pressure sensors are required for instrumentation of probes and test models in aerodynamic studies of complex unsteady flows. Optical-fiber pressure sensors promise potential advantages of small size and low cost in comparison with their electrical counterparts. We describe miniature Fabry-Perot cavity pressure sensors constructed by micromachining techniques in a turbine test application. The sensor bodies are 500 /spl mu/m squared, 300 /spl mu/m deep with a /spl sim/2 /spl mu/m-thick copper diaphragm electroplated on one face. The sensor cavity is formed between the diaphragm and the cleaved end of a single mode fiber sealed to the sensor by epoxy. Each sensor is addressed interferometrically in reflection by three wavelengths simultaneously, giving an unambiguous phase determination; a pressure sensitivity of 1.6 radbar/sup -1/ was measured, with a typical range of vacuum to 600 kPa. Five sensors were embedded in the trailing edge of a nozzle guide vane installed upstream of a rotor in a full-scale turbine stage transient test facility. Pressure signals in the trailing edge flow show marked structure at the 8 kHz blade passing frequency. To our knowledge, this is the first report of sensors located at the trailing edge of a normal-sized turbine blade.     

Miniaturized Two-Pressure Generator for Relative Humidity

The concept and design of a miniaturized two-pressure humidity generator are presented. The generator is suitable for achieving relative humidity ranging from 10% to 95% with uncertainties of under 1% at ambient temperature and can be used for the calibration of relative humidity instruments in the laboratory and on site. By virtue of the concept, the relative humidity achieved is traced to only two pressure measurements. Further references are not necessary. A special adjustment algorithm enables standard industrial pressure sensors to be used. The two pressure sensors are synchronized by aligning their readings at ambient pressure. The resulting correlation of the uncertainties leads to very small systematic errors in the humidity display. Each humidity generator can still be individually adjusted through comparison with a chilled-mirror hygrometer, the total uncertainty of the generator being largely determined by the uncertainty of this hygrometer. Any drift of the pressure sensors that occurs can be compensated at any time by performing an alignment at ambient pressure without changing the individual adjustment of the generator. It can be demonstrated that the uncertainty of the displayed humidity remains practically unchanged over the course of a year by virtue of this alignment process.