Sensors

Multiplexer for Multiple Sensors in a Vacuum Chamber

The multiplexer reduces the number of required feedthroughs and ports. John F. Kennedy Space Center, Florida Vacuum chamber testing at large facilities can require hundreds of instruments, necessitating even more feedthroughs. The number of instruments and sensors that can be fed into a vacuum chamber is limited by the number of feedthrough ports dedicated to instrumentation. Thus high-pin-count, mil-spec-style feedthroughs have been developed, but these are all custom-made and also expensive to make and replace. The high-pin-count feedthroughs also make it much harder to troubleshoot individual wires in case of a problem. By using a multiplexer within the vacuum chamber, the number of wires required per instrument can be reduced to much less than one. The multiplication of wires from within a vacuum chamber allows a drastic increase in sensor and instrumentation channel count, while using the same number of sensor ports and feedthroughs within an existing vacuum system.

Posted in: Physical Sciences, Sensors, Briefs, TSP

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Miniaturized Schottky Diode Sensors for Hydrogen and Hydrocarbon Detection at High Temperatures

The sensors have application in fuel leak detection, environmental monitoring, fire detection, security monitoring, and engine emission monitoring. John H. Glenn Research Center, Cleveland, Ohio A miniaturized Schottky diode hydrogen and hydrocarbon sensor with the structure of catalytic metal-metal oxide-silicon carbide (SiC) has been developed. The major innovation of this work is the use of the metal oxide, palladium oxide (PdOx), as a barrier layer between the catalytic metal and the SiC in the gas-sensing structure. A major advantage of adding a PdOx barrier layer between the gate metal and the SiC is to prevent and alleviate chemical reactions between the gate metal and the SiC. Without the PdOx barrier layer, the gate metal and the substrate can easily form metal silicides at high temperature, leading to diode structure disruption. The metal oxide barrier layer can be incorporated into a gas-sensing structure by standard deposition techniques in a controlled manner. This oxide naturally forms with Pd in Pd-based gas sensor systems and can disrupt the gas sensor structure when formed in situ in an uncontrolled manner. However, purposely including this oxide in the Schottky barrier structure produces a stable barrier layer that enables a stable and sensitive gas sensor structure.

Posted in: Physical Sciences, Sensors, Briefs

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Analog Ceramic Isolated Voltage Sensor

John H. Glenn Research Center, Cleveland, Ohio Galvanic isolated monitoring of voltages for launch vehicle, missiles, and space-deployed systems can be very challenging. Radiation exposure makes use of optics-based sensors difficult, as they can latch-up and become corrupted by the radiation environment; such devices can moreover be thermally challenged. Magnetic transformer-based methods of isolated voltage measurement require shielding to prevent stray magnetic interference from degrading or corrupting the readings; moreover, magnetic-based solutions are unable to measure voltages down to DC levels.

Posted in: Physical Sciences, Sensors, Briefs, TSP

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Flexible and Erectable Magnetic Field Response Sensors

Langley Research Center, Hampton, Virginia The means to make a flexible and/or erectable magnetic field response sensor, a geometrically fixed capacitor mounting frame, a wireless dipstick, and an elastically flexible capacitor support have been developed. Either the capacitor mounting frame or the flexible, erectable magnetic field response sensor can be developed to take measurements in hazardous conditions, or in containers with environmentally harmful contents, such as a gasoline storage tank.

Posted in: Physical Sciences, Sensors, Briefs, TSP

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Miniature Amperometric Solid Electrolyte Carbon Dioxide Sensor with Low Detection Limit

This sensor is applicable to fire detection, personal health monitoring, and environmental monitoring. John H. Glenn Research Center, Cleveland, Ohio A miniaturized amperometric electro-chemical (solid electrolyte) carbon dioxide (CO2) sensor using a novel and robust sensor design has been developed and demonstrated. Semiconductor microfabrication techniques were used in the sensor fabrication, and the sensor is fabricated for robust operation in a range of environments. The sensing area is 1.0 × 1.1 mm. The sensor is operated by applying voltage across the electrodes and measuring the resultant current flow at temperatures from 450 to 600 °C. Linear responses were achieved to the CO2 concentrations from 1% to 4%, and to the natural logrithmic concentrations of the CO2 from 0.02% to 1%. This CO2 sensor has the advantage of being simple to batch-fabricate, small in size, low in power consumption, easy to use, and fast with response time.

Posted in: Physical Sciences, Sensors, Briefs

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Robotic Fabric Moves and Contracts

Researchers are developing a robotic, sensor-embedded fabric that moves and contracts. Such an elastic technology could enable a new class of soft robots, stretchable garments, "g-suits" for pilots or astronauts to counteract acceleration effects, and lightweight, versatile robots to roam alien landscapes during space missions.The robotic fabric is a cotton material containing sensors made of a flexible polymer and threadlike strands of a shape-memory alloy. The strands return to a coiled shape when heated, causing the fabric to move."We have integrated both actuation and sensing, whereas most robotic fabrics currently in development feature only sensing or other electronic components that utilize conductive thread," said Rebecca Kramer, an assistant professor of mechanical engineering at Purdue University. "We also use standard sewing techniques to introduce the thread-like actuators and sensors into the fabric, so they could conceivably be integrated into the existing textile manufacturing infrastructure."SourceAlso: See other Sensors tech briefs.

Posted in: Materials, Plastics, Motion Control, Sensors, Aerospace, Machinery & Automation, Robotics, News

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Researchers Equip Robot with Novel Tactile Sensor

Researchers at MIT and Northeastern University have equipped a robot with a novel tactile sensor that lets it grasp a USB cable draped freely over a hook and insert it into a USB port.The sensor is an adaptation of a technology called GelSight, which was developed by the lab of Edward Adelson, the John and Dorothy Wilson Professor of Vision Science at MIT, and first described in 2009. The new sensor isn’t as sensitive as the original GelSight sensor, which could resolve details on the micrometer scale. But it’s smaller — small enough to fit on a robot’s gripper — and its processing algorithm is faster, so it can give the robot feedback in real time.A GelSight sensor — both the original and the new, robot-mounted version — consists of a slab of transparent, synthetic rubber coated on one side with a metallic paint. The rubber conforms to any object it’s pressed against, and the metallic paint evens out the light-reflective properties of diverse materials, making it much easier to make precise optical measurements.In the new device, the gel is mounted in a cubic plastic housing, with just the paint-covered face exposed. The four walls of the cube adjacent to the sensor face are translucent, and each conducts a different color of light — red, green, blue, or white — emitted by light-emitting diodes at the opposite end of the cube. When the gel is deformed, light bounces off of the metallic paint and is captured by a camera mounted on the same cube face as the diodes.From the different intensities of the different-colored light, the algorithms developed by Adelson’s team can infer the three-dimensional structure of ridges or depressions of the surface against which the sensor is pressed. Source Read other Sensors tech briefs.

Posted in: Photonics, Optics, Materials, Motion Control, Sensors, Lighting, LEDs, Machinery & Automation, Robotics, News

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