Sensor Housings Research Articles

Effect of Three-Dimensional-Printed Thermoplastics Used in Sensor Housings on Common Atmospheric Trace Gasses.

Low-cost air quality sensors (LCSs) are becoming more ubiquitous as individuals and communities seek to reduce their exposure to poor air quality. Compact, efficient, and aesthetically designed sensor housings that do not interfere with the target air quality measurements are a necessary component of a low-cost sensing system. The selection of appropriate housing material can be an important factor in air quality applications employing LCSs. Three-dimensional printing, specifically fused deposition modeling (FDM), is a standard for prototyping and small-scale custom plastics production because of its low cost and ability for rapid iteration. However, little information exists about whether FDM-printed thermoplastics affect measurements of trace atmospheric gasses. This study investigates how five different FDM-printed thermoplastics (ABS, PETG, PLA, PC, and PVDF) affect the concentration of five common atmospheric trace gasses (CO, CO2, NO, NO2, and VOCs). The laboratory results show that the thermoplastics, except for PVDF, exhibit VOC off-gassing. The results also indicate no to limited interaction between all of the thermoplastics and CO and CO2 and a small interaction between all of the thermoplastics and NO and NO2.

Influence of Temperature–Humidity Sensor Housing Depth on Concrete and Mortar Compressive Strength

Recent advancements in sensor technology have led to an increase in embedding sensors into construction materials for monitoring purposes in the construction industry. However, systematic research on the resulting changes to the material properties is still lacking. A previous study confirmed that the copper–nickel-plated housing of SHT-31 sensors affects the compressive strength of mortar. Moreover, it is necessary to conduct further research to determine if this analogous occurrence takes place in concrete. This study embedded temperature–humidity sensor housings in concrete at 10 mm, 20 mm, and 30 mm, before performing compression tests and a finite element analysis (FEA). The empirical findings indicate that the compressive strengths of concrete at 10 mm, 20 mm, and 30 mm depths were 26.1 MPa, 28.4 MPa, and 29.4 MPa, respectively. In contrast, the control concrete that did not have a sensor housing had a compressive strength of 31.9 MPa. In the case of mortar, a design strength of 28 MPa was achieved at a depth greater than 30 mm, while concrete reached this design strength at 20 mm. Based on these findings, embedding temperature–humidity sensor housings in concrete is recommended at depths greater than 20 mm from the surface. These results serve as important reference data for determining the optimal embedding depth of sensor housings in structures using cement-based materials.

Reducing the fluid loss in case of depressurization of tractors’ hydraulic drive

BACKGROUND:The operation of hydraulic drives of agricultural machinery is associated with the problem of leakage of fuel and lubricants, leading to contamination of water and soil. The most intense oil spill occurs when high-pressure hoses of hydraulic equipment are destroyed. The existing methods of solving the problem of oil leakage from high-pressure hoses have severe restrictions and high costs of their implementation. One of the effective methods of solving the problem is the use of hydraulic drive protection devices that disconnect the unpressurised section from the pressure source.
 AIMS:To develop an improved protection device an emergency stop device that controls a hydraulic drive with several types of hydraulic motors with a minimum number of device elements.
 MATERIALS AND METHODS:The design of a hydraulic drive emergency stop device (RUF Patent No. 2522013) installed in the hydraulic system of a tractor with single- and double-acting hydraulic cylinders has been developed. The method in use is a morphological analysis of the structure and distinctive features of existing engineering solutions.
 RESULTS:The shutdown unit and the terminal sensor of the emergency stop device compare the value of the hydraulic pump supply with the flow rate in the drain line. At the same time, the device is able to automatically adjust itself to their permissible difference, ensuring that there are no false responses when using double-cavity hydraulic cylinders with one rod. False responses when connecting a single-cavity hydraulic cylinder are prevented by using an additional flow sensor that blocks the shutdown unit. The fluid flow is throttled in the annular gaps between the pistons, sensor and shutdown unit housings; in this case, both pistons are mutually balanced.
 CONCLUSIONS:The proposed solution is aimed to eliminate significant oil throw-out form high-pressure hoses and makes it possible to use a single device for controlling the whole tractor hydraulic system. As a result, the weight and cost of the protection device reduce and the hydraulic drive scheme does not complicate significantly. The developed device does not demand additional power supply from the tractors on-board power circuit, as it operates with use of hydraulic energy. The protection device is applicable to hydraulic cylinders and hydraulic motors of various sizes thanks to ability of self-adjustment to the greatest difference in flow rate.

Propelling autonomous driving forward

DELO (Windach, Germany) has developed a flexible electronics adhesive that permanently seals sensor housings airtight and thus reliably protects components such as image sensors. DELO DUALBOND BS3770 meets the stringent requirements of the semiconductor and automotive industries and helps drive innovation in autonomous driving.

Sea-trial research on natural product-based antifouling paint applied to different underwater sensor housing materials

Biofouling is a common challenge for underwater sensors, especially for long-term in situ monitoring in marine environments. In this study, we assessed the antifouling efficacy of a paint containing a natural product camptothecin (CPT) on six materials (316 L stainless steel, TC4 titanium alloy, 7075 aluminum alloy, polyoxymethylene, polyvinyl chloride, and Teflon), which are frequently used in the construction of underwater sensor housings. Additionally, a buoy-based sea-trial was performed to test the antifouling performance of the CPT-based paint on housings of three in situ sensors used for practical seawater monitoring applications, namely a spectrophotometer for chemical oxygen demand (COD) measurements and two fluorimeters for biochemical oxygen demand (BOD) and chlorophyll a (Chl a) concentration measurements. The results showed significantly lower macrofouling coverage on the areas painted with the CPT-based paint compared to the unpainted areas for each tested material over 9 months of seawater immersion. The CPT-based paint exhibited different antifouling performance for the different materials; in particular, it exhibited better antifouling performance on the plastic materials compared to the metal materials. Furthermore, when applied on submersible sensor housings in the sea-trial test, the CPT-based paint kept the housings of the COD sensor and the Chl a sensor clean for over 4 months. In addition, the paint prevented fouling of the BOD sensor housing even after 6 months of seawater immersion. Thus, our results suggest that the CPT-based paint could be used as a potential solution to control the biofouling of sensor housings for long-term in situ applications in marine environments.

Graphene Oxide/Silver Nanocomposites as Antifouling Coating on Sensor Housing Materials

These days, sensors are widely used in a variety of underwater sites like marine monitoring, fish-farming and water quality monitoring. However, to achieve reliable sensor data from long-term monitoring in aqueous solution, several challenges still need to be solved. Biofilm formation both on sensor housings and membranes is among one of the most serious challenges, which strongly influences the sensor responds and the validity of the results. To prevent biofilm growth, a series of graphene oxide (GO)/silver nanoparticles (Ag NPs) nanocomposites (GOA) have been developed and coated on sensor housing materials, e.g. polypropylene. The antifouling property of the GOA nanocomposite has been demonstrated by antifouling tests using Halomonas. Pacifica (Baumann et al.) Dobson and Franzmann (ATCC® 27122) (H. Pacifica) and a mixture of marine algae. The antifouling property of GOA composites has been proved to be closely related to the dispersibility of Ag NP. The overall work might provide valuable insight into developing antifouling materials for sensors in general.

Experimental Study of Moisture Ingress in First and Second Levels of Electronic Housings

Moisture uptake of polymer materials used for electronic packaging and moisture ingress into automotive electronic sensor housings have been studied by exposure to constant and cyclic humidity and temperature conditions. The first-level housing is made of epoxy molding compound (EMC) and encapsulates the sensor silicon-chip. The second-level housing is made of polybutylene terephthalate and contains the EMC attached to a printed circuit board (PCB). The novel approach was to perform in situ measurements of the temperature and the relative humidity (RH) inside the EMC next to the silicon chip, and to measure the humidity transfer from outdoor to the second, and through the first-level housings up to the chip. The effect of the presence of PCB and the self-heating of components have been investigated. The results showed that the time constants for humidity to reach 63% of outdoor conditions are about 2 and 7 days at 60 °C for the second- and first-level housings, respectively. Exposure to cyclic conditions showed that the internal RH tends to reach a steady state, close to the mean value of the cyclic outdoor profile, while the presence of polymeric materials (as PCB) can act as a humidity buffer and absorb and desorb water when subjected to temperature fluctuations.

Guidelines for the design of tyre sensor housings

The next generation of tyre sensors will be bonded directly onto the inner liner (IL) in order to measure important parameters such as strain, vehicle load, contact pressure, the tyre-road friction coefficient or wear. Sensor packages (SP) have a sensor node, which is bonded and kept in position by a specifically designed rubber housing (RH). Since the measurements they provide to the car control unit are used to improve the active or passive safety of vehicles, these packages can be considered critical safety components that should be dimensioned carefully. A tyre analysis, whether statical or dynamical, in which the complete structure is considered, under any load, inflating pressure or temperature working condition is mainly oriented towards defining the tyre product. The insertion of an SP inside such a complex tyre model, with the purpose of only analysing its behaviour, would be too time consuming considering the strong nonlinear behaviour of the tyre model. Therefore, this work presents a method that can be used to define a computationally lightweight finite element method (FEM) simulation, which is able to recreate the working conditions to which an SP is subjected. The basic idea behind this method is to separate the analysis of the SP from the structural tyre analyses; the latter is only run once, independently. The first task is to impose the deformed shape on a simplified model of the tyre with a bonded SP. All the deformation states that occur during rolling are computed in a static FEM simulation. The second task is to apply the inertial forces that act on the SP, whether computed or measured directly on the tyre, as external loads. These tasks are implemented in user-defined routines that are executed by the FEM solver. The method permits the stress concentration inside the RH material volume to be identified, at any angular position of the wheel. This information is then used, during the design process, to identify the most suitable geometry to level out the stress distribution. The resulting shape can be tested under different boundary conditions, by substituting the corresponding data arrays, but using the same FEM model. Since the deformed shapes and inertial forces are stored as simple text matrices (which are also used to form a test library), they can be easily interchanged in a flexible way. This more extended design process can reduce the costs of prototyping moulds. The proposed methodology has been developed and tested for the Pirelli Cyber TM Tyre project.

Helium-tight Laser Beam Welding of Aluminum with Brillant Laser Beam Radiation

Abstract The substitution of steel as base metal for casings and packaging applications has increased during the last years. Especially aluminum with advantages in weight and machining effort has become a versatile solution for applications in fine mechanics (e.g. sensor housings) and automotive applications. Joining of aluminum components is more critical due to possible crack formation in the joining seam and uneven seam geometry. With the high intensity of brillant laser beam sources the specific challenges of aluminum welding can be overcome. Due to its hydrogen affinity and high degree of reflection for laser radiation at a wavelength of 1 μm (95%) aluminum needs to be welded with proper shielding gas support and high beam quality in order to avoid seam defects. Cracks and pores can lead to non-sufficient tightness for sensor applications and early failure. Housing components have been joined to form a functioning unit in order to seal electrical or measuring components, which are helium-tight for these applications.

Laser Glass Frit Sealing for Encapsulation of Vacuum Insulation Glasses

Abstract Laser glass frit sealing is a joining method predestined in electronics for the sealing of engineered materials housings in dimensions of some 1 mm2 to several 10 mm2. The application field ranges from encapsulation of display panels to sensor housings. Laser glass frit sealing enables a hermetical closure excluding humidity and gas penetration. But the seam quality is also interesting for other applications requiring a hermetical sealing. One application is the encapsulation of vacuum insulation glass. The gap between two panes must be evacuated for reducing the thermal conductivity. Only an efficient encapsulating technique ensures durable tight joints of two panes for years. Laser glass frit sealing is an alternative joining method even though the material properties of soda lime glass like sensitivity to thermal stresses are much higher as known from engineered materials. An adapted thermal management of the process is necessary to prevent the thermal stresses within the pane to achieve crack free and tight glass frit seams.

리드스위치 센서와 무선주파수를 이용한 막재료의 손상 모니터링에 관한 연구

PTEF membranes are used for roofing materials of membrane structures. PTEF is the abbreviation of Poly-tetra Fluotide-ethylene. These materials are consisted of fiberglass weave and polyetrfluoroethylene coating. Also, PTEF membranes have some problems of structural capacity by wind or snow load, etc. In this study, sensor housings using lead switches are bonding in PTFE membranes, Monitoring to changes tension and tear damages are studied using radio frequency. If tension is received on edged membranes, bonded lead switches of sensor housings will be destroyed by changes tension, and these become to send signals of damages at the connected radio frequency system with increased tension. Study of these functional membrane materials will be contributed to prevent water leakage and long-term maintenance of membrane structures.

Monitoring and modeling temperature variations inside silage stacks using novel wireless sensor networks

By monitoring silage temperature at different locations inside silage stacks, it is possible to detect any significant increases in temperature occurring during silage decomposition. The objectives of this study were: (1) to develop novel noninvasive wireless sensor nodes for measuring the temperature inside silage stacks; (2) to design a suitable sensor protection housing that prevents physical and chemical damage to the sensor; and (3) to mathematically model temperature variations inside a silage stack, using system identification techniques. The designed wireless nodes were used to monitor temperatures in a full-sized silage stack over 53 days. Results showed that the wireless sensor nodes accurately monitored the temperature inside the silage stack at depths of 25 and 50 cm and reliably transmitted the measured data through the network; between 98.9% and 99.4% of the packets disseminated from the sensor nodes were successfully delivered to the gateway. The reliable performance of the network confirmed the correct choice of network characteristics (i.e., frequency range of 433 MHz, a handshaking communication protocol, and 10 mW transmission power). The designed sensor housings were capable of withstanding the high loads that occurred during ensiling, storage, and feed-out. Mathematical models estimating the relations between the silage temperatures (at depths of 25 and 50 cm) and air and soil temperatures were obtained. Black-box modeling using the prediction error method (PEM) was selected as the identification method. Among different black-box models such as ARX, ARMAX, output-error (OE), and Box–Jenkins (BJ), with different model orders, a third-order Box–Jenkins model structure gave the best performance in terms of prediction accuracy. The success rate of the models proposed for silage temperature prediction ranged between 90.0% and 94.3%. Furthermore, there was no significant autocorrelation remaining in the residuals. The results of this study indicate that the designed wireless sensor nodes could potentially be used for detecting silage decomposition processes and improving the efficacy of silage conservation systems.

AE—Automation and Emerging Technologies: Noise Source Evaluation of a Real-time Soil Sensor, Part II: Dynamic Noise Sources

Research was conducted which examined the effects of dynamic elevation changes on a real-time soil organic matter sensor. Such soil sensors are intended to provide quick and economical methods of measuring soil properties. These soil properties are then useful in determining the proper chemical and fertilizer application rates for small sections of land. During the mapping process for organic matter content, it was found that the signal from the soil organic matter sensor contained several high-frequency components. A study was conducted to examine the relationship between dynamic elevation changes and the high-frequency components of the sensor signal.A finite element model of the sensor housing was created to obtain estimates of the first three natural frequencies of the system. These frequency values were then used to design laboratory experiments and to set data acquisition speeds for field tests. Controlled tests were performed at Herrick Laboratories, Purdue University, where the only noise source to the sensor system was dynamic changes in the sensor elevation relative to the soil surface. It was found that the level of error produced in the laboratory was significant enough to warrant study during field use. Field experiments were conducted in which acceleration inputs to the sensor assemble and the signal from the sensor were recorded by a portable data acquisition system. The relationship between the acceleration inputs and the sensor signal were examined using both single and multiple coherence analysis methods. The results of the coherence analysis indicated a stronger relationship between the acceleration inputs near the natural frequency of the sensor housing than at other frequencies. This suggests that great care should be taken to determine the resonant frequency of any such sensor housing and that components of the signal above this frequency should be removed via filters prior to using the data for analysis. For this sensor housing, no frequency component above 10 Hz should be used for the analysis of soil organic matter content. If higher sampling rates are desired, subsequent sensor housings should be designed such that the housing's natural frequency is raised.

In-plane ultrasonic velocity measurement

An improved system for measuring the velocity of ultrasonic signals within the plane of moving web-like materials, such as paper, paperboard and the like. In addition to velocity measurements of ultrasonic signals in the plane of the web in the MD and CD, one embodiment of the system in accordance with the present invention is also adapted to provide on-line indication of the polar specific stiffness of the moving web. In another embodiment of the invention, the velocity of ultrasonic signals in the plane of the web are measured by way of a plurality of ultrasonic transducers carried by synchronously driven wheels or cylinders, thus eliminating undue transducer wear due to any speed differences between the transducers and the web. In order to provide relatively constant contact force between the transducers and the webs, the transducers are mounted in a sensor housings which include a spring for biasing the transducer radially outwardly. The sensor housings are adapted to be easily and conveniently mounted to the carrier to provide a relatively constant contact force between the transducers and the moving web.

Method and system of measuring ultrasonic signals in the plane of a moving web

An improved system for measuring the velocity of ultrasonic signals within the plane of moving web-like materials, such as paper, paperboard and the like. In addition to velocity measurements of ultrasonic signals in the plane of the web in the machine direction, MD, and a cross direction, CD, generally perpendicular to the direction of the traveling web, therefor, one embodiment of the system in accordance with the present invention is also adapted to provide on-line indication of the polar specific stiffness of the moving web. In another embodiment of the invention, the velocity of ultrasonic signals in the plane of the web are measured by way of a plurality of ultrasonic transducers carried by synchronously driven wheels or cylinders, thus eliminating undue transducer wear due to any speed differences between the transducers and the web. In order to provide relatively constant contact force between the transducers and the webs, the transducers are mounted in a sensor housings which include a spring for biasing the transducer radially outwardly. The sensor housings are adapted to be easily and conveniently mounted to the carrier to provide a relatively constant contact force between the transducers and the moving web.

Heat losses associated with continuous venovenous haemodiafiltration in intensive care patients

Objective: To determine the magnitude of heat loss associated with the use of continuous venovenous haemodiafiltration (CVVHD), and the effect of warming the dialysate and insulating the circuit. Design: Extracorporeal temperature decrease was measured by thermocouples inserted into injectate sensor housings across the standard CVVHD circuit, and across circuits with dialysate warmed in a 40°C bath and/or insulated by aluminium foil. Setting: Intensive Care Unit (ICU) of a tertiary referral centre. Subjects: Twelve critically ill patients undergoing CVVHD. Main results: Mean extracorporeal temperature decrease using a standard circuit was 4.4°C (95% confidence interval [CI], 3.9-4.7), 3,000 kJ (710 kcal) per day would be required on average to maintain thermal homeostasis. Warming dialysate fluid reduced mean temperature decrease to 2.9°C (95% CI, 2.7-3.2), but aluminium foil insulation did not have a significant effect. Conclusion: Heat loss is a significant proportion of expected daily energy requirements. We therefore recommend warming dialysate fluid in normothermic and hypothermic patients.

Heat losses associated with continuous venovenous haemodiafiltration in intensive care patients

Objective: To determine the magnitude of heat loss associated with the use of continuous venovenous haemodiafiltration (CVVHD), and the effect of warming the dialysate and insulating the circuit. Design: Extracorporeal temperature decrease was measured by thermocouples inserted into injectate sensor housings across the standard CVVHD circuit, and across circuits with dialysate warmed in a 40°C bath and/or insulated by aluminium foil. Setting: Intensive Care Unit (ICU) of a tertiary referral centre. Subjects: Twelve critically ill patients undergoing CVVHD. Main results: Mean extracorporeal temperature decrease using a standard circuit was 4.4°C (95% confidence interval [CI], 3.9-4.7), 3,000 kJ (710 kcal) per day would be required on average to maintain thermal homeostasis. Warming dialysate fluid reduced mean temperature decrease to 2.9°C (95% CI, 2.7-3.2), but aluminium foil insulation did not have a significant effect. Conclusion: Heat loss is a significant proportion of expected daily energy requiremen...

Configuration and optimization of semiconductor gas sensors as gas chromatographic detectors

A tin oxide, gas-sensitive semiconductor sensor was configured as a gas chromatographic detector and its performance was optimized. Two sensor housings were compared but little difference was found in performance. The flow rate and temperature of the column and the internal heater voltage of the sensor affected both the sensitivity and peak shape. The temperature of the sensor surface was the most critical parameter. Optimal conditions for the gas chromatographic detection of a mixture of alkanes (C 1–C 5) and hydrogen were identified by using the simplex technique. The detection limit for hydrogen was improved by a factor of five to 20 ppb (v/v), illustrating the value of optimization and the excellent sensitivity of the detector. It is concluded that semiconductor gas sensors offer significant advantages as gas chromatographic detectors for the determination of reducing gases.

FIBER-OPTICAL MEASUREMENTS OF MECHANICALLY AND CHEMICALLY DISPERSED OIL IN WATER

ABSTRACT A new fiber optical transmittance meter has been designed to measure oil concentrations in water. No electronic components are placed in the underwater sensor housings which are made relatively small to avoid influence on the surroundings. Both the light emitting diode and the receiver are synchroned demodulated. This together with AC-linked amplifiers in both the sender and receiver electronics give appropriate noise reduction. A transmittance meter was calibrated in a 1,0000:1 laboratory tank. Results from this calibration with mechanically dispersed Ekofisk crude oil and Reginol SAE 30 water-in-oil emulsion are presented. It was found that the beam attenuation increased almost exponentially up to a certain oil concentration which was a function of the particle size distribution and length of the waterpath of the light beam. The time changes in the concentration of dispersed oil under breaking waves in a wave tank in the laboratory have been measured at different depths below the surface. It was found that the oil concentrations decreased almost exponentially below the surface down to a depth approximately equal to the height of the breaking wave. During a full scale field experiment with oil in the North Sea in May 1982 the oil leakage under two different oil booms was measured with a beam transmittance meter at 1.5 m depth about 5 m behind the oil booms. Two-minute mean values of the beam transmittance were recorded. The measurements showed large variations in the oil concentrations behind the oil booms. Transmittance meter measurements also were carried out during offshore full scale tests with different chemical dispersants. The instruments have been towed at different depths from small boats passing through the slicks, measuring oil concentrations continuously at different levels simultaneously under the slicks. At Frigg in June 1984, the concentration of dispersed oil at 1, 2, and 3 m depth varied from (approximately) 0 to 60 ppm under one slick.