A MEMS Nanopositioner With Integrated Tip for Scanning Tunneling Microscopy
Not provided.
Engineering↗
SEARCH · Search NASA
Results for “(MEMS)”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Position sensing circuit for an electrostatically driven MEMS device
The present disclosure relates to a system for detecting movement of a microelectromechanical system (MEMS) device. The system uses a drive voltage signal source for generating a low frequency drive voltage signal for driving the MEMS device. An excitation signal source may be used for generating an excitation signal which is also applied to the MEMS device. The excitation signal has a frequency which is above a physical response capability of the MEMS device, such that operation of the MEMS device is not significantly affected by the excitation signal. A sensing impedance is used to help generate a signal which is responsive to the capacitance of the MEMS device. The capacitance of the MEMS device changes in response to movement of the MEMS device. An output subsystem is provided which responds to changes sensed by the sensing impedance, and which produces an output voltage signal. A filter filters the output voltage signal to produce a filtered output voltage signal. The filtered output voltage signal is indicative of a position of the MEMS device.
Panas, Robert Matthew↗
Development of an MEMS ultrasonic microphone array system and its application to compressed wavefield imaging of concrete
Abstract Although contactless ultrasonic wavefield imaging shows potential for effective nondestructive inspection of various engineering materials, it has been rarely applied to concrete materials owing to technical challenges including low signal-to-noise ratio (SNR) caused by inherent heterogeneity of concrete. This paper presents development of a multi-channel MEMS ultrasonic microphone array system and its application to compressed wavefield imaging of concrete materials. The developed multi-channel MEMS ultrasonic microphone array system contains eight MEMS ultrasonic microphone elements and a signal conditioning circuit that enables measurements of ultrasonic signals with high SNR. A compressed sensing approach, based on the multiple measurement vector (MMV) concept, is applied to reconstruct a full dense ultrasonic wavefield data from sparsely sampled ultrasonic wavefield data. Experiments are carried out on a laboratory concrete sample to verify the performance of the developed MEMS microphone array system and proposed compressed sensing approach and then large-scale concrete samples to demonstrate practical application. The experimental results demonstrate that the developed MEMS microphone array system provides high-quality (SNR > 20 dB) ultrasonic data collected from concrete elements; furthermore, the proposed compressed sensing approach provides accurate reconstruction of dense wavefield data, as determined by peak signal-to-noise ratio (PSNR), from sparsely measured wavefield data with compression ratios up to 85% and PSNR above 25 dB in data collected form realistic large-scale concrete samples. By combining the MEMS array system and compressed sensing approach, the total ultrasonic data acquisition time needed to produce dense wavefield data can be significantly reduced.
Instruments & Instrumentation↗
Acoustic MEMS Sensor Array for Quench Detection of CICC Superconducting Cables
Here, a novel quench detection method using micro-electro-mechanical system (MEMS) sensor technology has been investigated in use for high temperature superconducting (HTS) conductors such REBCO tape cables. The sensor array along a superconducting cable, such as a cable-in-conduit-conductor (CICC), is installed in a cooling channel. It will allow sensitive and quick detection for a local quench of a superconducting cable. This work has confirmed that a quench of a single REBCO tape can be detected in liquid nitrogen by a MEMS piezoelectric microphone sensor. The quench detection design utilizing a MEMS sensor array method is discussed for the case of a toroidal field (TF) magnets of a fusion Tokamak device.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Representing cropping systems with the MEMS 2 ecosystem model
Abstract Croplands have been the focus of substantial investigation due to their considerable potential for sequestering carbon. Understanding the potential for soil organic carbon (SOC) sequestration and necessary management strategies will be enabled with accurate process‐based models. Accurately representing crop growth and agricultural practices will be critical for realistic SOC modeling. The MEMS 2 model incorporates a current understanding of SOC formation and stabilization, measurable SOC pools, and deep SOC dynamics and is seen as a highly promising tool to inform management intervention for SOC sequestration. Thus far, MEMS 2 has been developed to represent grasslands. In this study, we further developed MEMS 2 to model annual grain crops and common agricultural practices, such as irrigation, fertilization, harvesting, and tillage. Using four Ameriflux sites, we demonstrated an accurate simulation of crop growth and development. Model performance was strong for simulating aboveground biomass (index of agreement [d] range of 0.89–0.98) and green leaf area index (dfrom 0.90 to 0.96) across corn, soybean, and winter wheat. Good agreement with observations was also achieved for net ecosystem CO 2 exchange (dfrom 0.90 to 0.96), evapotranspiration (dfrom 0.91 to 0.94), and soil temperature (dof 0.96), while discrepancy with the available soil water content data remain (dfrom 0.14 to 0.81 at four depths to 100 cm). While we will continue model testing and improvement, MEMS 2 (version 2.14) has now demonstrated its ability to effectively simulate the growth of common grain crops and practices.
Agriculture↗
Simulating measurable ecosystem carbon and nitrogen dynamics with the mechanistically defined MEMS 2.0 model
Abstract. For decades, predominant soil biogeochemical models have used conceptual soil organic matter (SOM) pools and only simulated them to a shallow depth in soil. Efforts to overcome these limitations have prompted the development of the new generation SOM models, including MEMS 1.0, which represents measurable biophysical SOM fractions, over the entire root zone, and embodies recent understanding of the processes that govern SOM dynamics. Here we present the result of continued development of the MEMS model, version 2.0. MEMS 2.0 is a full ecosystem model with modules simulating plant growth with above- and belowground inputs, soil water and temperature by layer, decomposition of plant inputs and SOM, and mineralization and immobilization of nitrogen (N). The model simulates two commonly measured SOM pools – particulate and mineral-associated organic matter (POM and MAOM, respectively). We present results of calibration and validation of the model with several grassland sites in the US. MEMS 2.0 generally captured the soil carbon (C) stocks (R2 of 0.89 and 0.6 for calibration and validation, respectively) and their distributions between POM and MAOM throughout the entire soil profile. The simulated soil N matches measurements but with lower accuracy (R2 of 0.73 and 0.31 for calibration and validation of total N in SOM, respectively) than for soil C. Simulated soil water and temperature were compared with measurements, and the accuracy is comparable to the other commonly used models. The seasonal variation in gross primary production (GPP; R2 = 0.83), ecosystem respiration (ER; R2 = 0.89), net ecosystem exchange (NEE; R2 = 0.67), and evapotranspiration (ET; R2 = 0.71) was well captured by the model. We will further develop the model to represent forest and agricultural systems and improve it to incorporate new understanding of SOM decomposition.
54 ENVIRONMENTAL SCIENCES↗
Using non-invasive MEMS pressure sensors for measuring building envelope air leakage
Micro-electromechanical systems (MEMS)-based sensors have seen significant improvements in accuracy and cost over the past several years, and due to the need for altitude sensing in unmanned aerial vehicles and wearable technologies, absolute pressure sensors have shown the most dramatic improvements. This paper investigates applications of MEMS sensors in commercial buildings, including pairing two absolute pressure sensors to determine differential pressures between different locations in and around buildings. Differential pressure measurements are commonly made in commercial buildings for a number of applications, including static pressure measurements for variable-speed supply fan control, air balancing in hospitals, and for envelope and duct air leakage testing. This paper focuses specifically on envelope air-leakage testing applications of these sensors. The use of continuous pressure measurements in addition to one-time non-intrusive outdoor airflow measurements of rooftop packaged units is investigated. A comparison with standardized leakage testing indicated that continuous measurements with MEMS pressure-sensors were able to estimate envelope leakage to within 3–16% of the standardized test result. In addition, the magnitude and stability of differential pressure differences that can be resolved with absolute pressure sensors are also investigated in the laboratory and the field. Results show that the sensors can be effectively used for pressures seen in low rise buildings with rooftop units.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
A MEMS Gyroscope for Reliable Long Duration Measurement While Drilling at 300°C
The 300°C Microelectromechanical system (MEMS) gyroscope project aims to contribute to DOE’s goal of increased geothermal drilling efficiency by 2025 through the development of a 300°C MEMS gyroscope for Measurement While Drilling (MWD). At the conclusion of the 2-year project, the team will develop a 300°C capable MEMS gyroscope containing GE’s patented Multi-Ring Gyroscope Transducer (MRGT) design, custom Silicon-On-Insulator (SOI) based frontend and feedback control electronics, and with demonstrated functionality and lifetime beyond 1000 hours. The project is divided into two budget periods with Go/No-Go decision at the end of the first budget period. The goal for the first budget period is to establish the feasibility of the MRGT and electronics design for meeting the 300°C performance requirements. The goal for the second budget period is to integrate the MRGT with the SOI-based application specific integrated circuit (ASIC) and demonstrate capability to operate at 300°C for 1000 hours. In Budget Period 1 we met the phase 1 goal. We successfully validated the combined MRG, electronics and packaging capability entitlement to achieving 0.5 degrees azimuth uncertainty while enabling operation at significantly higher temperatures than the state-of-the-art. In Budget Period 2, we successfully completed the integration of the MRGT and ASIC with associated high temperature, high reliability packaging to demonstrate the performance and functionality of the integrated gyroscope across the temperature range from room temperature to at 300°C. Furthermore, the team demonstrated operating life of >1,000 hours at 300°C, thus providing a validation of application-relevant lifetime capability.
15 GEOTHERMAL ENERGY↗
A High-Throughput MEMS-Based Differential Scanning Calorimeter for Direct Thermal Characterization of Antibodies
Calorimeters, which can be used for rapid thermal characterization of biomolecules, are getting intense attention in drug development. This paper presents a novel MEMS-based differential scanning calorimeter (DSC) for direct thermal characterization of protein samples. The DSC consisted of a pair of temperature sensors made by vanadium oxide (VOx) film with a temperature coefficient of resistivity of –0.025/K at 300 K, a microfluidic device with high thermal insulation (2.8 K/mW), and a Peltier heater for linear temperature scanning. The DSC exhibited high sensitivity (6.1 µV/µW), low noise (0.4 µW), high scanning rate (45 K/min), and low sample consumption volume (0.63 µL). The MEMS DSC was verified by measuring the temperature-induced denaturation of lysozyme at different pH, and then used to study the thermal stability of a monoclonal antibody (mAb), an antigen-binding fragment (Fab), and a dual variable domain immunoglobulin (DVD-Ig) at pH = 6. The results showed that lysozyme is a stable protein in the pH range of 4.0–8.0. The protein stability study revealed that the transition temperatures of the intact Fab fragment, mAb, and DVD proteins were comparable with conformational stability results obtained using conventional commercial DSC. These studies demonstrated that the MEMS DSC is an effective tool for directly understanding the thermal stability of antibodies in a high-throughput and low-cost manner compared to conventional calorimeters.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
A MEMS dynamic mechanical analyzer for in situ viscoelastic characterization of 3D printed nanostructures
Cellular metamaterial structures with sub-micron features have shown the ability to become excellent energy absorbing materials for impact mitigation due to the enhanced mechanical properties of materials at the nanoscale. However, in order to optimize the design of these energy absorbing metamaterial structures we need to be able to measure the dynamic properties of the sub-micron features such as storage and loss moduli and the loss factor. Therefore, at scale testing is required to capture the scale, temperature, and strain rate dependent material properties of these nanoscale materials. This study presents the design, fabrication, and calibration of a MEMS-based dynamic mechanical analyzer (DMA) that can be directly integrated with the two photon lithography (TPL) process commonly used to fabricate metamaterial structures with nanoscale features. The MEMS-based DMA consists of a chevron style thermal actuator used to generate a tensile load on the structure and two differential capacitive sensors on each side of the structure used to measure load and displacement. This design demonstrated 1.5 ± 0.75 nm displacement resolution and 104 ± 52 nN load resolution, respectively. Dynamic mechanical analysis was successfully conducted on a single nanowire feature printed between the load and displacement stages of the MEMS device with testing frequencies ranging between 0.01–10 Hz and testing temperatures ranging between 22 °C–47 °C. These initial tests on an exemplar TPL part demonstrate that the printed nanowire behaves as a viscoelastic material wherein the transition from glassy to viscous behavior has already set in at the room temperature.
42 ENGINEERING↗
A sensing material-free and simple readout MEMS sensor for detecting Helium
Abstract In this work, we report a method that enables a standard electrostatic MEMS device to perform complex sensing functionalities, such as detecting the presence of helium without a sensing material or a conditioning circuit. Helium is a noble, odorless, non-reactive gas that is very challenging to detect. It is used in critical applications such as storing nuclear fuel waste inside a dry cask. In these applications, its leakage from the dry cask may indicate the cask's safe operation's degradation. A departure from the common practice of exciting the MEMS around its mechanical resonance, the method is based on exciting the MEMS around its electrical resonance circuit. This method shows that the tiny difference between the air dielectric constant (1.00059) and helium (1.000067) corresponding to only a few Femtofarad level capacitances produces a 25 mV difference without a conditioning circuit. Simulation results confirmed those findings and explored the sensor response at different operation conditions. This method eliminates the need for a heated microstructure and the need for absorption material. This method is not limited to gas sensing. It can be applied to other sensing mechanisms, such as acceleration and pressure measurements, and eliminate the complex circuit to read small capacitance in these applications.
Mohaidat, Sulaiman↗
MEMS RF accelerators for nuclear energy and advanced manufacturing
Energetic ions are widely used to develop radiation hard structural materials and fuels for advanced nuclear energy. Ion beams are also used to generate neutrons for nuclear materials testing, as well as in a series of high impact, high value adding manufacturing processes (ranging from doping of semiconductors to hardening of materials against wear and to increase bio-compatibility of materials). But to date, high power beams of high energy ions are simply too expensive because they are delivered from large single beam accelerators. We have recently demonstrated that MEMS technology enables massively parallel, low cost batch fabrication of ion beams. We propose to scale intense ion accelerators based on MEMS (micro-electro mechanical systems) to high beam power (>10 kW). With our approach, hundreds to thousands of ion beamlets will be densely packed on silicon wafers. Ions are injected and accelerated across gaps formed in stacks of wafers, leading to uniquely high current densities for intense ion accelerators with variable kinetic energy (0.1 to 10 MeV) and variable ion species. Our team brings together experts in high power ion accelerators from Lawrence Berkeley National Laboratory and leading experts in MEMS technology from Cornell University. We will deliver a disruptive technology of low cost, flexible and massively scalable ion accelerators that will enable the rapid development of radiation hard nuclear materials for advanced nuclear energy and enable new applications in manufacturing.
43 PARTICLE ACCELERATORS↗
Acoustic MEMS Sensor Array for Quench Detection of CICC Superconducting Cables
A novel quench detection method using microelectro- mechanical system (MEMS) sensor technology has been investigated in use for high temperature superconducting (HTS) conductors such REBCO tape cables. The sensor array along a superconducting cable, such as a cable-in-conduit-conductor (CICC), is installed in a cooling channel. It will allow sensitive and quick detection for a local quench of a superconducting cable. This work has confirmed that a quench of a single REBCO tape can be detected in liquid nitrogen by a MEMS piezoelectric microphone sensor. The quench detection design utilizing a MEMS sensor array method is discussed for the case of a toroidal field (TF) magnets of a fusion Tokamak device.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
MEMS nanopositioner and method of fabrication
A microelectromechanical (MEMS) device is provided. The MEMS device comprises a substrate and a movable structure flexurally connected to the substrate, capable of moving in relation to the substrate, wherein the movable structure further comprising two or more segments having at least one mechanical connection between said segments to provide structural integrity of the moving structure; and wherein the at least one mechanical connection electrically isolates at least two segments.
Moheimani, Seyed Omid Reza↗
Sub-Degree-Per-Hour MEMS Gyroscope for Measurement While Drilling at 300°C
The orientation module of MWD tool offers the critical drill bit orientation information, including azimuth, inclination and toolface in order to control the path of wellbore. Although high end navigation grade gyroscope can meet the accuracy requirement for azimuth finding, the requirements of cost, size and reliability under harsh environment have largely limited the deployment of gyroscopes in MWD tools. To overcome these constraints, GE Research has developed a low cost, MEMS based Multi-Ring Gyroscope (MRG) capable of azimuth-seeking in MWD applications at 300°C. The MRG prototype has been demonstrated to achieve angular random walk (ARW) better than 0.003 deg/rt(hr) and bias instability of 0.01 deg/hr, capable of meeting azimuth finding accuracy better than 0.25 deg. It has further been tested to remain fully operational at 300 °C.
15 GEOTHERMAL ENERGY↗
Coolant Pressure Evaluations for a MEMS Sensor-Array Quench Detection in REBCO CICC Superconducting Cables
Here, the initial quench pressure developments for a CICC cable of REBCO tapes have been investigated by numerical analyzing the first law of thermodynamics. The temperature and pressure rise due to the quench has been evaluated for a REBCO CICC conductor operated in helium gas coolant at 26 K. Additionally, a MEMS sensor-in-tube array method has been proposed and discussed for quench detection.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
The Application of Quaternions to Strap-Down MEMS Sensor Data
We describe the mathematical transformations required to convert the data recorded using typical 6-axis microelectromechanical systems (MEMS) sensor packages (3-axis rate gyroscopes and 3-axis accelerometers) when attached to an object undergoing a short duration loading event, such as blast loading, where inertial data alone are sufficient to track the object motion. By using the quaternion description, the complex object rotations and displacements that typically occur are translated into the more convenient earth frame of reference. An illustrative example is presented where a large and heavy object was thrown by the action of a very strong air blast in a complex manner. The data conversion process yielded an accurate animation of the object’s subsequent motion.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Modeling and Design Parameter Optimization to Improve the Sensitivity of a Bimorph Polysilicon-Based MEMS Sensor for Helium Detection
Helium is integral in several industries, including nuclear waste management and semiconductors. Thus, developing a sensing method for detecting helium is essential to ensure the proper operation of such facilities. Several approaches can be used for helium detection, including based on the high thermal conductivity of helium, which is several times higher than air. This work utilizes the high thermal conductivity of helium to design and analyze a bimorph MEMS sensor for helium sensing applications. COMSOL Multiphysics software (version 6.2) is used to carry out this investigation. The sensor is constructed from poly-silicon and SiO 2 materials with a trenched cantilever beam configuration. The sensor is electrically heated, and its morphed displacement depends on the surrounding gas’s composition, which decreases in the presence of helium. Several factors were investigated to probe their effect on the sensor’s sensitivity to helium, including the thickness of the poly-silicon layer, the configuration of the trench, and the thickness and location of SiO 2 layer. The simulations showed that the best performance, up to 2 ppm helium detection level, can be achieved with thinner beams and medium trench lengths.
47 OTHER INSTRUMENTATION↗