Miniature Pressure Sensor Research Articles

From Piezoelectric Sensor to Measuring System

In 1959, Hans Conrad Sonderegger established Kistler Instrumente AG in Switzerland. In 1957, Walter P. Kistler and Hans Conrad Sonderegger had already founded Kistler Instrument Corp. in the USA and Hans Conrad Sonderegger had established Kistler Instruments in Switzerland. In 1958, Kistler launched the first universal miniature pressure sensor. In the years that followed Kistler set milestones in the field of sensor technology with its innovations and expanded its global presence. In 2009, its jubilee year, Kistler is adding the new KiBox, the mobile in-vehicle combustion analysis system, to its range of products.

Micromachined Pressure Sensors on Optical Fiber Tip

This paper reports the development of a miniature pressure sensor on the optical fiber tip for in vitro measurements of rodent intradiscal pressure. The sensor element is biocompatible and can be fabricated by simple, batch-fabrication methods in a non-cleanroom environment with good device-to-device uniformity. The fabricated sensor element has an outer diameter of only 366 μm, which is small enough to be inserted into the rodent discs without disrupting the structure or altering the intradiscal pressures. In the calibration, the sensor element exhibits a linear response to the applied pressure over the range of 0 - 70 kPa, with a sensitivity of 0.0206 μm/kPa and a resolution of 0.17 kPa.

Analysis and design of a wide micro beam as a pressure gauge for high sensitivity MEMS fingerprint sensors

Sensitivity improvement is a challenging issue in miniature pressure sensors. To improve sensitivity and linearity of the device, a wide micro beam structure has been proposed to gauge capacitance changes caused by the applied pressure in a capacitive MEMS fingerprint sensor. Bending behavior of the device and the effect of the protrusion geometry on partial loading of the micro beam has been analytically investigated. Based on the idea of efficient loading of the wide micro beam, an improved design for the capacitive fingerprint sensor is developed to increase sensitivity. It is shown with FEM simulations that the micro wide beam design is superior to the common membrane based MEMS fingerprint sensors in terms of sensitivity and linearity.

A211 小型グロー点火エンジンの性能評価 : 燃料組成と空燃比がエンジンの性能に与える影響(燃焼科学と技術の新展開V)

Devices such as robots have become increasingly sophisticated and compact, the amount of energy required for their operation has increased . For those devices, small portable distributed power sources with higher energy density than the conventional battery are required. In this research, we focused on the small glow-ignition engine developed for model airplanes to verify a possibility that glow-ignition small engines replace electric cells as an energy source for micro-size machines. In order to clarify the combustion process, a miniature pressure sensor was built into the cylinder head, and pressure fluctuation was measured. Analysis was conducted to detect heat release and ignition timing. The base engine was a commercial glow-ignition four-stroke engine with a swept volume of 4.89 cc.

Pressure–Frequency Sensing Subxiphoid Access System for Use in Percutaneous Cardiac Electrophysiology: Prototype Design and Pilot Study Results

We have designed, built, and tested an early prototype of a novel subxiphoid access system intended to facilitate epicardial electrophysiology, but with possible applications elsewhere in the body. The present version of the system consists of a commercially available insertion needle, a miniature pressure sensor and interconnect tubing, read-out electronics to monitor the pressures measured during the access procedure, and a host computer with user-interface software. The nominal resolution of the system is < 0.1 mmHg, and it has deviations from linearity of < 1%. During a pilot series of human clinical studies with this system, as well as in an auxiliary study done with an independent method, we observed that the pericardial space contained pressure-frequency components related to both the heart rate and respiratory rate, while the thorax contained components related only to the respiratory rate, a previously unobserved finding that could facilitate access to the pericardial space. We present and discuss the design principles, details of construction, and performance characteristics of this system.

Free swelling and confined smart hydrogels for applications in chemomechanical sensors for physiological monitoring

We investigate thin films of “smart” polymer hydrogels used to convert miniature pressure sensors into novel chemomechanical sensors. In this versatile sensing approach, a smart hydrogel is confined between a porous membrane and the diaphragm of a piezoresistive pressure transducer. An increase in the environmental analyte concentration, as sensed through the pores of the membrane, is detected by measuring the change in pressure exerted by the hydrogel on the pressure transducer diaphragm. We compare the response of such a sensor with the response of a free-swelling hydrogel identical to the one used within the sensor. The sensor and the free hydrogel are observed to have comparable mean response times. However, the time-dependent response curve of the sensor, unlike that of the free hydrogel, is highly asymmetric between swelling and deswelling, with a smaller time constant for deswelling. We also investigate novel methods for increasing sensor sensitivity, such as use of a two-layer membrane with a nanoporous polymer inner layer, and pre-loading of the hydrogel under pressure. In ionic strength response tests, use of an inner membrane increases sensor sensitivity without increasing mean response time, an effect that varies with membrane water fraction.

Sediment dynamic responses of coastal salt marsh to typhoon “KAEMI” in Quanzhou Bay, Fujian Province, China

In order to understand the mechanisms of coastal protection by salt marshes during typhoon events, in situ measurements of water level, tidal current speed and direction, and suspended sediment concentration (SSC) were carried out using Electromagnetic Current Meter (EMCM, AEM HR), miniature pressure sensor (MkV/D) and Seapoint Turbidity Meter (STM) sensor on a tidal flat in Quanzhou Bay, during the period when the typhoon “KAEMI” was passing through the region. The analysis of the data obtained shows that the near-bed current speed within the Spartina alterniflora marsh was generally below 5 cm s−1, which was apparently smaller than on the adjacent bare flat (i.e. 5–30 cm s−1). The change in the near-bed current speed in response to the typhoon event was not significant within the S. alterniflora marsh, but the current direction was influenced by the typhoon. The effect of the typhoon on the SSC was highly significant, with the SSC reaching 13 to 19 times the values on the bare flat or within the marsh under fair weather conditions; the near-bed SSC within the marsh was higher than on the bare flat, after the typhoon landed. The near-bed suspended sediment fluxes within the marsh and on the bare flat during the typhoon event were both enhanced, i.e., 4 times larger than under fair weather conditions. During the ebb, the bottom shear stress on the bare flat exceeded the critical shear stress for sediment motion for most of the ebb duration of the tide and, therefore, the bed sediment was eroding, with the erosion flux after the typhoon landed being around 2 to 3 times the value associated with fair weather conditions. In contrast, within the S. alterniflora marsh, the bottom shear stress was mostly lower than the critical shear stress for sediment motion, or lower than the critical shear stress for the maintenance of suspension; hence, the marsh surface was dominated by settling processes, with a settling flux during the typhoon being 3 to 6 times compared with the fair weather situations. The settling flux during the ebb was up to twice the magnitude for the flood. The comparison of sediment dynamic processes between the S. alterniflora marsh and the bare flat demonstrates that during the typhoon event the bare flat was dominated by erosion, whilst the presence of S. alterniflora favored the accretion of suspended sediment.

Effect of Systolic Duration on Mechanical Heart Valve Cavitation in a Pneumatic Ventricular Assist Device: Using a Monoleaflet Valve

The cavitation intensity of a mechanical heart valve (MHV) may differ according to the geometry of the blood pump and driving mechanism. Our group is currently developing a pneumatic ventricular assist device (VAD), and the effects of different operating conditions on MHV cavitation in our pneumatic VAD were investigated. Tests were conducted under physiological pressure at heart rates ranging from 60 to 90 beats/min and at a systolic duration ranging from 38% to 43%. The valve-closing velocity was measured using a charge-coupled device (CCD) laser displacement sensor, and images of MHV cavitation were recorded using a high-speed video camera. A miniature pressure sensor was mounted 10 mm away from the inlet valve surface. The data were stored at a 1-MHz sampling rate using a digital oscilloscope. The pressure signal was band-pass filtered between 35 and 200 kHz using a digital filter. The cavitation bubbles were concentrated at the inlet valve stop, and were caused mainly by the squeeze flow. The band-pass filtered root mean squared (RMS) pressure and cavitation cycle duration increased with the closing velocity of the inlet valve. At a low heart rate and low systolic duration, the inlet valve closed before the outlet valve opened, which caused no cavitation bubbles to form around the valve stop.

Miniature fiber optic pressure sensor with composite polymer-metal diaphragm for intradiscal pressure measurements

We developed a miniature fiber optic pressure sensor system and utilized it for in vitro intradiscal pressure measurements for rodents. One of the unique features of this work is the design and fabrication of a sensor element with a multilayer polymer-metal diaphragm. This diaphragm consists of a base polyimide layer (150 nm thick), a metal reflective layer (1 microm thick), and another polyimide layer for protection and isolation (150 nm thick). The sensor element is biocompatible and can be fabricated by simple, batch-fabrication methods in a non-cleanroom environment with good device-to-device uniformity. The fabricated sensor element has an outer diameter of only 366 microm, which is small enough to be inserted into the rodent discs without disrupting the structure or altering the intradiscal pressures. In the calibration and in vitro rodent intradiscal pressure measurements, the sensor element exhibits a linear response to the applied pressure over the range of 0-70 kPa, with a sensitivity of 0.0206 microm/kPa and a resolution of 0.17 kPa. To our best knowledge, this work is the first successful demonstration of rodent intradiscal pressure measurements.

Ground-Based Simulation of Complex Maneuvers of a Delta-Wing Aircraft

Ground-Based Simulation of Complex Maneuvers of a Delta-Wing Aircraft

A fast telemetric pressure and temperature sensor system for medical applications

A new implantable sensor system with RF data and energy link is presented. This system comprises a telemetry made of standard components and is connected via a micro cable to a well-known miniature pressure and temperature sensor−ASIC. Due to this separation of telemetry and sensor the total size at the measurement spot could be reduced to less than 4 Fr. (1.2 mm) including the whole encapsulation of the sensor. The complete system provides telemetric data transfer of pressure measurements, with at least 30 Hz and parallel temperature measurements of the arterial blood with up to 1 Hz. The system performance is demonstrated for in vitro as well as in vivo animal testings. The telemetry with electronics and the corresponding software in the implant as well as the reader station is built up modular. This gives the opportunity to equip the implant with additional different sensors.

Miniaturization of components and systems for space using MEMS-technology

Development of MEMS-based (micro electro mechanical system) components and subsystems for space applications has been pursued by various research groups and organizations around the world for at least two decades. The main driver for developing MEMS-based components for space is the miniaturization that can be achieved. Miniaturization can not only save orders of magnitude in mass and volume of individual components, but it can also allow increased redundancy, and enable novel spacecraft designs and mission scenarios. However, the commercial breakthrough of MEMS has not occurred within the space business as it has within other branches such as the IT/telecom or automotive industries, or as it has in biotech or life science applications. A main explanation to this is the highly conservative attitude to new technology within the space community. This conservatism is in many senses motivated by a very low risk acceptance in the few and costly space projects that actually ends with a space flight. To overcome this threshold there is a strong need for flight opportunities where reasonable risks can be accepted. Currently there are a few flight opportunities allowing extensive use of new technology in space, but one of the exceptions is the PRISMA program. PRISMA is an international (Sweden, Germany, France, Denmark, Norway, Greece) technology demonstration program with focus on rendezvous and formation flying. It is a two satellite LEO mission with a launch scheduled for the first half of 2009. On PRISMA, a number of novel technologies e.g. RF metrology sensor for Darwin, autonomous formation flying based on GPS and vision-based sensors, ADN-based “green propulsion” will be demonstrated in space for the first time. One of the satellites will also have a miniaturized propulsion system onboard based on MEMS-technology. This novel propulsion system includes two microthruster modules, each including four thrusters with micro- to milli-Newton thrust capability. The novelty of this micropropulsion system is that all critical components such as thrust chamber/nozzle assembly including internal heaters, valves and filters are manufactured using MEMS technology. Moreover, miniaturized pressure sensors, relying on MEMS technology, is also part of the system as a self-standing component. The flight opportunity on PRISMA represents one of the few and thus important opportunities to demonstrate MEMS technology in space. The present paper aims at describing this development effort and highlights the benefits of miniaturized components and systems for space using MEMS technology.

Wireless Acoustic Communication With a Miniature Pressure Sensor in the Pulmonary Artery for Disease Surveillance and Therapy of Patients With Congestive Heart Failure

The purpose of this study was to examine the feasibility of repeated pulmonary artery (PA) pressure determinations using a newly developed acoustic wireless implanted communication system. Congestive heart failure management strategies based on monitored intracardiac hemodynamics in patients receiving the best-available therapy may improve outcome. Although electromagnetic communication requires a large antenna for sufficient energy transfer, acoustic energy readily penetrates deep into the body, uses little energy, and uses small internal transducers for bidirectional operation. A miniature device was developed and implanted using right heart catheterization. The ability to obtain PA pressure from the implant using wireless acoustic communication was examined in 8 pigs and 10 patients with congestive heart failure. Macroscopic and histopathologic examinations were performed at 6 months after implantation. The accuracy of PA pressure measurement was determined by comparison with simultaneous pressures from a Millar catheter. The device was successfully implanted in the PA using right heart catheterization. There were no implantation or later device-related complications. Pulmonary artery pressure tracings were repeatedly obtained from all implants. Normal reactions to intravascular implant were observed macroscopically and in histologic sections. Standard deviations of the difference between implant and Millar PA diastolic pressure were 1.45 and 1.2 mm Hg (animals and humans, respectively). Data were useful for patient management. This pilot study demonstrates, for the first time, that acoustic wireless communication with a miniature implanted sensor is feasible and provides repeated PA pressure measurement. This feat makes possible multiple novel applications for monitoring and therapeutic interventions based on measurements from deeply implanted devices.

E112 超小型グロー点火エンジンの性能評価(内燃機関)

Although portable electric devices have become increasingly sophisticated and compact, the amount of energy required for their operation has increased and device performance may be restrained by the energy source in the near future. Small, portable distributed power sources with higher energy density than the conventional battery are required. In this research, we focused on the small glow-ignition engine developed for model airplanes. In order to clarify the combustion process, a miniature pressure sensor was built into the cylinder head, and pressure fluctuation was measured. Analysis was conducted to detect cycle-to-cycle variation. The base engine was a commercial glow-ignition four-stroke engine with a swept volume of 4.89cc. Although the nominal output was 368W, the value measured by this research was much lower.

Investigation of shock waves in explosive blasts using fibre optic pressure sensors**This paper was presented at the 13th International Conference on Sensors and Their Applications, held in Chatham, Kent, on 6–7 September 2005.

We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm2 in overall cross-section with rise times in the µs regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure–time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.

Miniature temperature-insensitive Fabry-Pe/spl acute/rot fiber-optic pressure sensor

We present a miniature fiber-optic pressure sensor with a diameter of only 125 mum. The sensor works as an extrinsic Fabry-Peacuterot interferometer and the cavity length can be controlled with a resolution of about several nanometers. Also the sensor sensitivity can be easily adjusted by controlling the sensor gauge length. A passive temperature compensation scheme was used to reduce most of the sensor's temperature dependence. Since the sensor is composed entirely of fused silica, it is reliable, biocompatible, corrosion resistant, and immune to electromagnetic interference and has high-temperature capability

High-temperature fiber-tip pressure sensor

This paper presents a miniature fiber-optic high-temperature pressure sensor fabricated on the tip of a singlemode (SM) fiber by means of fusion splicing, cleaving, and wet chemical etching. A new approach was developed to simplify the fabrication and greatly improve the sensitivity. The sensor is made entirely of fused silica, whose high-temperature sensing capability is explored in detail for the first time. Two sensors were tested up to 611/spl deg/C and 710/spl deg/C, respectively, showing excellent repeatability better than 0.62% and 1.4%. The maximum operating temperature is limited by the mechanical creep of the fused silica diaphragm.

インプラント埋入後の暫間義歯における粘膜調整材の緩圧効果の検討

The main objective of this study was to examine the influence of the thickness and its longitudinal change within the limited denture space on the stress releasing effect for installed implants during the healing period of a two-stage procedure. As for the tissue conditioning material, Tissue Conditioner (Shofu, Kyoto, Japan) with the designated powder liquid ratio was used. The force transmitted to the implant with the material 5 min after the mixing was measured by a miniature pressure sensor in the position of the implant head (Kyowa, Tokyo, Japan). Measurements were repeated with the material preserved in the water for one and two weeks. Load of 2 kg was applied with a 3-mm diameter round tip using a static loading machine for 2 min to the center of the flat type denture model. The model consisted of denture, mucosa, tissue conditioning material and implant where the first three variables were changed as in the oral cavity. Influence of thickness of each variable was examined longitudinally. Force measured with any thickness of tissue conditioning material was smaller than that without the material. The stress releasing effect did not change with change of the longitudinal material property up to two weeks. Within the limitations of our study, it was suggested that the stress releasing effect of the tissue conditioning material for the installed implant was not influenced by the thickness or change of longitudinal property.

Optical MEMS pressure sensor based on Fabry-Perot interferometry

By employing the surface and bulk micro-electro-mechanical system (MEMS) techniques, we design and demonstrate a simple and miniature optical Fabry-Perot interferometric pressure sensor, where the loaded pressure is gauged by measuring the spectrum shift of the reflected optical signal. From the simulation results based on a multiple cavities interference model, we find that the response range and sensitivity of this pressure sensor can be simply altered by adjusting the size of sensing area. The experimental results show that high linear response in the range of 0.2-1.0 Mpa and a reasonable sensitivity of 10.07 nm/MPa (spectrum shift/pressure) have been obtained for this sensor.

Design and analysis of new concept fast-response pressure probes

Two cylindrical fast-response pressure probes for unsteady flow measurements in turbomachinery have been designed and tested. Commercially available miniaturized pressure sensors have been used to ensure high reliability and low manufacturing costs. Analytical and numerical models have been applied to the design of the line–cavity system connecting the pressure tap and the (encapsulated) sensor, to improve the dynamic behaviour of the probes. Dynamic calibrations in a low-pressure shock tube have also been carried out to determine the probe transfer function and to extend the probe operating range beyond the resonance frequency of the line–cavity system. One of the new probes exhibits a frequency response of about 80 kHz in the range 0–35 kPa, a suitable value for most turbomachinery applications.