Embedded Pressure Sensors Research Articles

Analysis of pressure distribution and verification of pressure signal by changes load and velocity in chemical mechanical polishing

The Preston's equation which was known as the governing equation of the polishing results in CMP process is caused by the wafer pressure and velocity. It is very important for the pressure and velocity to examine the fundamental characteristics which have effects on the polishing results. In this study, the intelligent pad which can measure the pressure distribution delivered to the wafer by the independent change of the pressure and velocity in real-time was used. The intelligent pad has sheet shape of embedded pressure sensor and functions of pressure signal processing, saving and transmitting in real-time. The average and the deviation of pressure signals were calculated by extracting the signal value from the measured pressure distribution, and the quantitative analysis was conducted by using the full width at half maximum (FWHM) value of the probability density function. The suitability of pressure signal was confirmed by polishing the oxide wafer in the same experiment conditions. So, the average and deviation of the pressure signal value correspond with the material removal rate (MRR) and non-uniformity of the polishing result. In conclusion, the intelligent pad system will be a good monitoring tool to understand various phenomena in CMP process.

Shape Deposition Manufacturing of a Soft, Atraumatic, and Deployable Surgical Grasper

This paper details the design, analysis, fabrication, and validation of a deployable, atraumatic grasper intended for retraction and manipulation tasks in manual and robotic minimally invasive surgical (MIS) procedures. Fabricated using a combination of shape deposition manufacturing (SDM) and 3D printing, the device (which acts as a deployable end-effector for robotic platforms) has the potential to reduce the risk of intraoperative hemorrhage by providing a soft, compliant interface between delicate tissue structures and the metal laparoscopic forceps and graspers that are currently used to manipulate and retract these structures on an ad hoc basis. This paper introduces a general analytical framework for designing SDM fingers where the desire is to predict the shape and the transmission ratio, and this framework was used to design a multijointed grasper that relies on geometric trapping to manipulate tissue, rather than friction or pinching, to provide a safe, stable, adaptive, and conformable means for manipulation. Passive structural compliance, coupled with active grip force monitoring enabled by embedded pressure sensors, helps to reduce the cognitive load on the surgeon. Initial manipulation tasks in a simulated environment have demonstrated that the device can be deployed though a 15 mm trocar and develop a stable grasp using Intuitive Surgical's daVinci robotic platform to deftly manipulate a tissue analog.

Real-time measurements of temperature, pressure and moisture profiles in High-Performance Concrete exposed to high temperatures during neutron radiography imaging

High-Performance Concrete (HPC) is particularly prone to explosive spalling when exposed to high temperature. Although the exact causes that lead to spalling are still being debated, moisture transport during heating plays an important role in all proposed mechanisms. In this study, slabs made of high-performance, low water-to-binder ratio mortars with addition of superabsorbent polymers (SAP) and polypropylene fibers (PP) were heated from one side on a temperature-controlled plate up to 550°C. A combination of measurements was performed simultaneously on the same sample: moisture profiles via neutron radiography, temperature profiles with embedded thermocouples and pore pressure evolution with embedded pressure sensors. Spalling occurred in the sample with SAP, where sharp profiles of moisture and temperature were observed. No spalling occurred when PP-fibers were introduced in addition to SAP. The experimental procedure described here is essential for developing and verifying numerical models and studying measures against fire spalling risk in HPC.

Insulin Micropump with Embedded Pressure Sensors for Failure Detection and Delivery of Accurate Monitoring

Improved glycemic control with insulin pump therapy in patients with type 1 diabetes mellitus has shown gradual reductions in nephropathy and retinopathy. More recently, the emerging concept of the artificial pancreas, comprising an insulin pump coupled to a continuous glucose meter and a control algorithm, would become the next major breakthrough in diabetes care. The patient safety and the efficiency of the therapy are directly derived from the delivery accuracy of rapid-acting insulin. For this purpose, a specific precision-oriented design of micropump has been built. The device, made of a stack of three silicon wafers, comprises two check valves and a pumping membrane that is actuated against stop limiters by a piezo actuator. Two membranes comprising piezoresistive strain gauges have been implemented to measure the pressure in the pumping chamber and at the outlet of the pump. Their high sensitivity makes possible the monitoring of the pumping accuracy with a tolerance of ±5% for each individual stroke of 200 nL. The capability of these sensors to monitor priming, reservoir overpressure, reservoir emptying, outlet occlusion and valve leakage has also been studied.

Development of intelligent pad monitoring system and application to analysis of pressure distribution in chemical mechanical polishing process

Most of polishing conditions are not consistent during the polishing process such as pressure, velocity, temperature, pad surface asperity and slurry flow determine the CMP performance. Traditionally, these parameters are detected by various monitoring methods on CMP polisher. This study introduces a new concept of intelligent pad system with multiple sensors and peripheral devices such as memory, CPU, battery, transmitter and so on. The main functions of the intelligent pad are sensing the change of major parameters and data processing in real-time during the polishing process. The developed intelligent pad has nine points of embedded pressure sensor and makes data processing, saving and transmitting in real-time. Experimentally, the intelligent pad system was evaluated to understand carrier behavior and pressure distribution. Finally, the analysis of pressure distribution using the intelligent pad turned out a useful method to understand the polishing head behavior and the polishing profile.

Fabrication and calibration of a sub-miniature 5-hole probe with embedded pressure sensors for use in extremely confined and complex flow areas in turbomachinery research facilities

Multi-hole pressure probes are often employed in experimental facilities to measure the three dimensional flow field due to their ability to simultaneously provide the distributions of the static and total pressures as well as the three components of the velocity vectors. In cases where these probes are employed in turbomachinery research facilities it is essential for them to be accurate, respond to local parameter disturbances quickly and exhibit a high flow angle spatial sensitivity. Thus, the physical dimensions of the probe must be as small as possible. In addition the small size of the probe reduces the flow blockage and the corresponding local disturbances of the flow, especially when it approaches the solid boundaries of the blade channels. The present study refers to the fabrication and calibration of a sub-miniature in dimensions 5-hole probe, for use in complex internal flow areas arising in turbomachinery research. In order to reduce the need for a longer sampling time as the size of the probe gets smaller, the length of the stem that transfers the pressure from the tip of the probe to the sensor has to be minimized. This effect was compensated by embedding the pressure sensors right at the end of the probe׳s stem. This minimizes the air volume and thus the oscillations inside the flexible connecting tubes that usually connect each port of the probe to its corresponding pressure sensor. The fabrication methodology of the probe and data acquisition system is extensively described, as well as the non-nulling method employed for the calibration. Furthermore, application of the probe on a reference configuration geometry often used in turbomachinery research is illustrated in order to validate the effectiveness and novel characteristics of the probe. The result is a construction and calibration technique that allows the relevant laboratories to build on their own such instruments that may cost several thousand dollars (or euros) when bought from the open market.

Biomechanical modeling to prevent ischial pressure ulcers

With 300,000 paraplegic persons only in France, ischial pressure ulcers represent a major public health issue. They result from the buttocks׳ soft tissues compression by the bony prominences. Unfortunately, the current clinical techniques, with – in the best case – embedded pressure sensor mats, are insufficient to prevent them because most are due to high internal strains which can occur even with low pressures at the skin surface. Therefore, improving prevention requires using a biomechanical model to estimate internal strains from skin surface pressures. However, the buttocks׳ soft tissues׳ stiffness is still unknown. This paper provides a stiffness sensitivity analysis using a finite element model. Different layers with distinct Neo Hookean materials simulate the skin, fat and muscles. With Young moduli in the range [100–500kPa], [25–35kPa], and [80–140kPa] for the skin, fat, and muscles, respectively, maximum internal strains reach realistic 50 to 60% values. The fat and muscle stiffnesses have an important influence on the strain variations, while skin stiffness is less influent. Simulating different sitting postures and changing the muscle thickness also result in a variation in the internal strains.

Design and Development of a Sensorized Wireless Toy for Measuring Infants' Manual Actions

The development of grasping is an important milestone that infants encounter during the first months of life. Novel approaches for measuring infants' manual actions are based on sensorized platform usable in natural settings, such as instrumented wireless toys that could be exploited for diagnosis and rehabilitation purposes. A new sensorized wireless toy has been designed and developed with embedded pressure sensors and audio-visual feedback. The fulfillment of clinical specifications has been proved through mechanical and electrical characterization. Infants showed a good grade of acceptance to such kind of tools, as confirmed by the results of preliminary tests that involved nine healthy infants: the dimensions fulfill infants' anthropometrics, the device is robust and safe, the acquired signals are in the expected range and the wireless communication is stable. Although achieved only through preliminary tests, such results confirm the hypothesis that this typology of instrumented toys could be useful for quantitative monitoring and measuring infants' motor development and ready to be evaluated for assessing motor skills through appropriate clinical trials.

Electrofluidic pressure sensor embedded microfluidic device: a study of endothelial cells under hydrostatic pressure and shear stress combinations

Various microfluidic cell culture devices have been developed for in vitro cell studies because of their capabilities to reconstitute in vivo microenvironments. However, controlling flows in microfluidic devices is not straightforward due to the wide varieties of fluidic properties of biological samples. Currently, flow observations mainly depend on optical imaging and macro scale transducers, which usually require sophisticated instrumentation and are difficult to scale up. Without real time monitoring, the control of flows can only rely on theoretical calculations and numerical simulations. Consequently, these devices have difficulty in being broadly exploited in biological research. This paper reports a microfluidic device with embedded pressure sensors constructed using electrofluidic circuits, which are electrical circuits built by fluidic channels filled with ionic liquid. A microfluidic device culturing endothelial cells under various shear stress and hydrostatic pressure combinations is developed to demonstrate this concept. The device combines the concepts of electrofluidic circuits for pressure sensing, and an equivalent circuit model to design the cell culture channels. In the experiments, human umbilical vein endothelial cells (HUVECs) are cultured in the device with a continuous medium perfusion, which provides the combinatory mechanical stimulations, while the hydrostatic pressures are monitored in real time to ensure the desired culture conditions. The experimental results demonstrate the importance of real time pressure monitoring, and how both mechanical stimulations affect the HUVEC culture. This developed microfluidic device is simple, robust, and can be easily scaled up for high-throughput experiments. Furthermore, the device provides a practical platform for an in vitro cell culture under well-controlled and dynamic microenvironments.

Development of intelligent pad and application to analysis of pressure distribution on polishing pad in CMP process

ABSTRACTMost of polishing conditions are not consistent during the polishing process such as pressure, velocity, temperature, pad surface asperity and slurry flow which determine the CMP performance. Traditionally, these parameters are detected by various monitoring methods on CMP polisher. This study introduces a new concept of intelligent pad system with multiple sensors and peripheral devices such as memory, CPU, battery, transmitter and so on. The main functions of the intelligent pad are sensing the change of major parameters and data processing in real-time during the polishing process. The developed intelligent pad has nine points of embedded pressure sensor and makes data processing, saving, and transmitting in real-time. Experimentally, the intelligent pad system was evaluated to understand carrier behavior and pressure distribution. Finally, the analysis of pressure distribution using the intelligent pad turned out a useful method to understand the polishing head behavior and the polishing profile.

CMOS-MEMS Based Current Mirror MOSFET Embedded Pressure Sensor for Healthcare and Biomedical Applications

This paper reports on the design and optimization of current mirror MOSFET embedded pressure sensor. A current mirror circuit with an output current of 1 mA integrated with a pressure sensing n-channel MOSFET has been designed using standard 5 µm CMOS technology. The channel region of the pressure sensing MOSFET forms the flexible diaphragm as well as the strain sensing element. The piezoresistive effect in MOSFET has been exploited for the calculation of strain induced carrier mobility variation. The output transistor of the current mirror forms the active pressure sensing MOSFET which produces a change in its drain current as a result of altered channel mobility under externally applied pressure. COMSOL Multiphysics is utilized for the simulation of pressure sensing structure and Tspice is employed to evaluate the characteristics of the current mirror pressure sensing circuit. Simulation results show that the pressure sensor has a sensitivity of 10.01 mV/MPa. The sensing structure has been optimized through simulation for enhancing the sensor sensitivity to 276.65 mV/MPa. These CMOS-MEMS based pressure sensors integrated with signal processing circuitry on the same chip can be used for healthcare and biomedical applications.

Assessment of adaptive walking performance

Although mostly negative aspects are reported to be associated with gait variability, irregular walking is needed when walking performance has to be adapted to specific environmental conditions. The aim of this study was to evaluate the test–retest reliability and discriminative ability of a measure to assess adaptive walking performance and to identify parameters associated with test performance in young and elderly subjects. Eighteen older (mean age 78.1 years) and 19 young women (mean age 30.8 years) were instructed to walk as precisely as possible over a defined course targeting 26 arbitrarily positioned rectangle boxes fixed on an instrumented walk way with embedded pressure sensors. ICC1,1 of 0.79 demonstrated sufficient reliability in the cohort of older women. Targeting was significantly worse (or deviation was larger) in older women than in young women (mean 3.20cm versus 2.27cm, p=0.005). Mean gait speed of the older women was higher during the test (0.50m/s versus 0.40m/s, p=0.020), but not during unconstrained walking (1.15m/s versus 1.50m/s, p<0.001). The deviation measure classified 78% of the subjects into correct age group (sensitivity 67%, specificity 90%, p=0.003). Adaptive walking performance was associated with parameters describing physical performance as well as with cognitive executive function. This study shows that this test of adaptive walking performance is a reliable measure of irregular walking with ability to discriminate between young and older subjects. Our results suggest that older persons might try to camouflage their lack of accuracy during adaptive walking by higher gait speed.

Novel Time-Resolved Pressure Measurements on an Airfoil at a Low Reynolds Number

2This work focuses on time-resolved surface pressure measurements on an airfoil operating in low Reynolds number flows. The experiments were performed on a NACA 0018 airfoil at a chord Reynolds number of 100,000. The results are presented for two angles of attack, eight and twelve degrees, representative of two flow regimes common to airfoil operation at low Reynolds numbers, separation bubble formation and separation without subsequent reattachment. An array of twenty-five microphones was embedded into the airfoil model to facilitate multi-point, time-resolved surface pressure measurements. A comparative analysis of mean pressure, velocity, and time-resolved pressure measurements is presented to determine what flow characteristics can be estimated using embedded pressure sensors. The results show that surface pressure fluctuations increase markedly past the separation location, reflecting the increase in the magnitude of velocity fluctuations in the separated shear layer undergoing laminar-to-turbulent transition. In the separation bubble, surface pressure fluctuations peak just upstream of reattachment, suggesting that time- resolved surface pressure measurements can be used to identify the presence and estimate the length of the separation region. The analysis of simultaneous velocity and pressure measurements shows that the characteristics of flow disturbances growing in the separated shear layer can be estimated from microphone measurements. In particular, the dominant frequency, convective speed, and growth rate of disturbances can be estimated without performing the extensive tests typically required when conventional velocity measurement techniques are used. However, when separation occurs without reattachment, the relatively large distance between the transitioning separated shear layer and the airfoil surface results in lower magnitude surface pressure fluctuations, which substantially increases the uncertainty of estimating flow characteristics based on microphone measurements for this flow regime.

PXI-Based High Performance Data Acquisition System for Fuel Injection System of Diesel Engine

High-performance data acquisition system is designed on the foundation of studying the working principle of diesel engine fuel injection system and analyzing the characteristics of fuel injection pressure waveform. The fuel injection pressure waveform can be accurately captured by the data acquisition system which based on embedded pressure sensors and NI PXI-6143 multifunction data acquisition card, and then the fuel injection opening pressure and the maximum injection pressure can be calculated. Fuel supply advance angle can be obtained by comparing the injection pressure waveform and the top dead center signal. The signal to noise ratio of the data acquisition system is very high, and the operating parameters of fuel supply system can be calculated without software filter. The fuel injection opening pressure, maximum injection pressure and fuel supply advance angle were obtained in situ test on 6L20/27 diesel. The operating parameters all coincide with the technology data sheet given by the factory.

The Key Role of the Closed-loop Combustion Control for Exploiting the Potential of Biodiesel in a Modern Diesel Engine for Passenger Car Applications

The present paper describes the results of a cooperative research project between GM Powertrain Europe and Istituto Motori CNR aimed at studying the capability of GM Combustion Closed-Loop Control (CLCC) in enabling seamless operation with high biodiesel blending levels in a modern diesel engine for passenger car applications. As a matter of fact, fuelling modern electronically-controlled diesel engines with high blends of biodiesel leads to a performance reduction of about 12-15% at rated power and up to 30% in the low-end torque, while increasing significantly the engine-out NOx emissions. These effects are both due to the interaction of the biodiesel properties with the control logic of the electronic control unit, which is calibrated for diesel operation. However, as the authors previously demonstrated, if engine calibration is re-tuned for biodiesel fuelling, the above mentioned drawbacks can be compensated and the biodiesel environmental inner qualities can be fully deployed. In order to enable such calibration re-tuning, it is fundamental to achieve a reliable biodiesel blending detection, and to use it for realtime combustion optimization, chiefly by optimizing the injection train. Therefore, the authors investigated the capability of CLCC to detect biodiesel blending ratio on the recently released 2.0L Euro5 GM diesel engine equipped with embedded pressure sensors in the glow plugs. Various blends of biodiesel were tested, notably 20% by volume (B20), 50% (B50) and pure biodiesel (B100). Tests on the multicylinder engine were carried out in a wide range of engine operating points for the complete characterization of the biodiesel performance in the NEDC cycle. The results demonstrated the successful capability of the CLCC control to detect biodiesel blending with reasonable accuracy and to implement the corrective actions to avoid emission drift and performance losses.

Parameters affecting the sensitivity of LTCC pressure sensors

Purpose – The purpose of this paper is to demonstrate the influence of material properties and fabrication technique on the performance of an embedded pressure sensor. Based on conducted theoretical analysis a suitable material and technological technique that gave the best behavior of designed sensor was chosen for its fabrication. This is verified on the example of a resonant pressure sensor, designed for operation in the MHz range.Design/methodology/approach – A sensor module is fabricated using the low temperature co‐fired ceramics (LTCC) technology and sputtering technique for electrodes deposition. The module comprises an inductor connected with a variable capacitor formed by the sensor membranes in a parallel LC circuit. An extensive parallel analysis of sensors performance for sensors with thick film (screen‐printed) and thin film (sputtered) electrodes is demonstrated. Mechanical and electrical parameters (Young's modulus and permittivity) of different tape materials that are considered for senso...

Monitoring of velocity and pressure fields within an axial turbine

In the framework of the consortium of R&D on hydraulic machines launched by the LAMH (Hydraulic Machines Laboratory of Laval University) in November 2007, a five holes unsteady pressure probe using embedded pressure sensors has been developed. Such probe allows us to obtain the unsteady static pressure, total pressure and the three flow velocity components. This paper aims to present this new five holes unsteady pressure probe, used and results for a propeller turbine.

Responsiveness of 2 Procedures for Measurement of Temporal and Spatial Gait Parameters in Older Adults

To determine the responsiveness of the GAITRite system and a stopwatch-footfall count technique for measurement of walking speed, cadence, and stride length during comfortable and fast-paced walking. Criterion standard. Research laboratory in a physical therapy education program. Twenty-four healthy volunteers (13 men, 11 women; mean age 74.5 years) without lower extremity injury or history of falls. Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected comfortable and fast walking speeds. Simultaneously, an examiner, using a stopwatch, recorded the elapsed time necessary to cross the mat and counted the number of complete footfalls. Walking speed, cadence, and stride length were compared between the GAITRite system and the stopwatch-footfall count technique for both comfortable and fast walking speeds. Responsiveness values for each procedure were described by the 95% minimal detectable change (MDC). During comfortable self-paced walking, MDC values for the stopwatch-footfall count technique ranged from 10% to 65% greater than those obtained for the GAITRite system. During fast self-paced walking MDC values for the stopwatch-footfall count technique ranged from 26% to 65% larger than those measured by the GAITRite system for the temporal and spatial gait performance parameters. When measured by the GAITRite system, the 95% MDC values for temporal and spatial gait parameters of older community-dwelling adults were more responsive to change than those obtained by the stopwatch-footfall technique. Clinicians should recognize that self-selected walking speed, cadence, and stride length when obtained by an instrumented walkway must be equal to or exceed 12.6 cm/s, 8.4 steps/min, or 7 cm, respectively, for the change to be considered real change and not from measurement error.

Agreement Between the GAITRite Walkway System and a Stopwatch–Footfall Count Method for Measurement of Temporal and Spatial Gait Parameters

Youdas JW, Hollman JH, Aalbers MJ, Ahrenholz HN, Aten RA, Cremers JJ. Agreement between the GAITRite walkway system and a stopwatch–footfall count method for measurement of temporal and spatial gait parameters. Objective To determine the agreement for measurements of stride length, cadence, and walking speed obtained from the GAITRite system and the stopwatch–footfall count technique. Design Criterion standard. Setting Research laboratory in a physical therapy education program. Participants Forty healthy volunteers (13 men, 27 women) without lower-extremity injury. Interventions Participants walked across a GAITRite mat with embedded pressure sensors at their self-selected walking speed. Simultaneously, an examiner used a stopwatch to record the elapsed time necessary to cross the mat and counted the number of complete footfalls. Main Outcome Measures Walking speed, cadence, and stride-length measures were compared between the GAITRite system and the stopwatch–footfall count technique. Results Correlation coefficients comparing both systems were .97 for walking speed, .75 for cadence, and .85 for stride length. Ninety-five percent of the time we would expect the between-methods differences to range between .09 and −.05m/s for walking speed, between −1.5 and −24.3 steps/min for cadence, and between .01 and .37m for stride length. Conclusions This study shows that the GAITRite and stopwatch–footfall count methods lack clinically acceptable agreement for the measurements of cadence and stride length in a group of healthy volunteers walking at their self-selected speeds. Clinicians who require precise measurement of cadence and stride length should consider using the GAITRite system instead of the stopwatch–footfall count technique.

Introducing the pressure-sensing palatograph – the next frontier in electropalatography

Primary Objective. To extend the capabilities of current electropalatography(EPG) systems by developing a pressure-sensing EPG system. An initial trial of aprototype pressure-sensing palate will be presented.Research Design. The processes involved in designing the pressure sensors areoutlined, with Hall effect transistors being selected. These units are compact,offer high sensitivity and are inexpensive. An initial prototype acrylic palate wasconstructed with five embedded pressure sensors. Syllable repetitions wererecorded from one adult female.Main Outcomes, Results and Future Directions. The pressure-sensing palate wascapable of recording dynamic tongue-to-palate pressures, with minimal to nointerference to speech detected perceptually. With a restricted number of sensors,problems were encountered in optimally positioning the sensors to detect theconsonant lingual pressures. Further developments are planned for variousaspects of the pressure-sensing system.Conclusions. Although only in the prototype stage, the pressure-sensing palaterepresents the new generation of EPG. Comprehensive analysis of tongue-topalatecontacts, including pressure measures, is expected to enable more specificand effective therapeutic techniques to be developed for a variety of speechdisorders.