Sensors/Data Acquisition

Active Remote-Sensing Radiometer

This technology can be used for security screening and security imaging, as well as automotive navigation in dust and fog conditions where machine vision performs poorly. NASA’s Jet Propulsion Laboratory, Pasadena, California Millimeter-wave (mm-wave) imaging techniques are already a popular solution for imaging through dust and fog. While mm-wave offers excellent penetration to dust when compared with infrared or optical sensing, the longer wavelengths create many problems associated with the specular response of surfaces at mm-wave. Generally, at mm-wave, the geometry and orientation of the target object has a larger influence on captured contrast than material properties by several orders of magnitude. While these effects can be somewhat mitigated with a radar imager, there is still a large contrast dependence on beam-target angle, and images are still entirely derived from geometry instead of material compositions.

Posted in: Briefs, Sensors

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Pressure Sensor Using Piezoelectric Bending Resonators

This technology applies to any application in which high-pressure measurement is required. NASA’s Jet Propulsion Laboratory, Pasadena, California A pressure sensor was developed based on a piezoelectric bending resonator. The resonator is covered and mechanically coupled with a sealed enclosure. The impedance spectrum of the resonator changes with the deformation of the enclosure induced by pressure or force applied to the enclosure. The changes in the impedance can be mapped to exchanges in the external environment, and the shifts in the resonance can be used to track the pressure.

Posted in: Briefs, Sensors

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Using a Ubiquitous Conductor to Power and Interrogate Wireless Passive Sensors and Construct a Sensor Network

Sensor nodes are used in health monitoring of aircraft and vehicles, building monitoring, human activity monitoring, and information collection for fire and disaster rescue. Langley Research Center, Hampton, Virginia Many methods have been developed for interrogation of wireless passive sensors. Surface acoustic wave (SAW) sensors and RF reflection sensors can receive and reflect electronic magnetic waves that are broadcast and received by the antennas. The interrogation distance can range from several meters to tens of meters. These previously developed technologies have limitations. The signal frequency is very high (usually at GHz level), which increases the difficulties in signal processing and interrogation system development, and the interrogation distance is limited by the power attenuation in the space. Longer interrogation distance requires higher-power-density electromagnetic (EM) waves in signal broadcasting, which increases the EMI hazard to environments.

Posted in: Briefs, Sensors

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Full-Field Inverse Finite Element Method for Deformed Shape- and Stress-Sensing of Plate and Shell Structures

Real-time reconstruction of full-field structural displacements helps provide feedback to the actuation and control systems of aerospace vehicles with morphed-wing architecture. Langley Research Center, Hampton, Virginia Structural health management systems that, by way of real-time monitoring, help mitigate accidents due to structural failures, will become integral technologies of the next-generation aerospace vehicles. Advanced sensor arrays and signal processing technologies are utilized to provide optimally distributed in-situ sensor information related to the states of strain, temperature, and aerodynamic pressure. To process the massive quantities of measured data, and to infer physically admissible structural behavior, requires robust and computationally efficient physics-based algorithms.

Posted in: Briefs, Sensors

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Pressure-Optimized Optical Breath Gas Analyzer for Portable Life Support Systems

This instrument could be used in trace gas sensor applications where rapid sampling in a compact package is required, such as in human-occupied closed volumes. Lyndon B. Johnson Space Center, Houston, Texas Optical detection of gaseous carbon dioxide, water vapor (humidity), and oxygen is desired in Portable Life Support Systems (PLSS) incorporating state-of-the-art CO2 scrubbing architectures. Earlier broadband detectors are nearing their end of life, and recent advances in laser diode technology make replacement of earlier technology compelling. The function of the infrared gas transducer used during extravehicular activity (EVA) in the current spacesuit is to measure and report the concentration of CO2 in the ventilation loop. The next-generation PLSS requires next-generation CO2 sensing technology with performance beyond that presently in use on the Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within spacesuits demands that optical sensors meet stringent size, weight, and power requirements. A sensor is required that is compact, low power, low mass, has rapid sampling capability, can operate over a wide pressure range, and can recover from condensing conditions.

Posted in: Briefs, Sensors

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Lightweight Metal Rubber Textile Sensor for In-Situ Lunar Health Monitoring

This personnel status sensor can be used to measure, record, and communicate heart rate, electrocardiogram (ECG), and core body temperature information. Lyndon B. Johnson Space Center, Houston, Texas Extravehicular activities (EVAs) are dangerous to astronauts for a number of reasons, including high levels of physical exertion, potential for impacts by space debris particulates that could puncture the spacesuit and cause depressurization, Moon dust exposure that is abrasive and possibly biologically harmful, harsh thermal environments (extreme variation from –150 to >120 ºC when directly exposed to the Sun), and extreme low pressure (≈0 atm). These harsh environmental conditions inevitably lead to emotional pressure and stress, which directly impact physiological condition and potentially affect performance and safety. Because many EVA operations are time-consuming, astronauts may be extremely uncomfortable for several continuous hours.

Posted in: Briefs, Sensors

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Force Sensors For Design

IN RECENT YEARS, factors such as consumer demand and a tough economy have pushed OEMs to produce sleeker, smaller, and less costly products than in the past. This forces designers to spec or engineer parts for increasingly tight space requirements. In this difficult situation, even small components such as force sensors can play a surprisingly big role in the development of successful solutions. A patented, thin-film, flexible but accurate force sensor was developed specifically to target industry needs for a low-cost, unobtrusive, force or pressure-measurement solution. The unique technology eliminates many of the challenges plaguing engineers in the design of streamlined products.

Posted in: White Papers, Sensors

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