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All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers

A family of experimental highly miniaturized field-effect transistors (FETs) is based on exploitation of the electrical properties of nanofibers of polyaniline/ polyethylene oxide (PANi/PEO) doped with camphorsulfonic acid. These polymer-based FETs have the potential for becoming building blocks of relatively inexpensive, low-voltage, highspeed logic circuits that could supplant complementary metal oxide/semiconductor (CMOS) logic circuits. The development of these polymerbased FETs offers advantages over the competing development of FETs based on carbon nanotubes. Whereas it is difficult to control the molecular structures and, hence, the electrical properties of carbon nanotubes, it is easy to tailor the electrical properties of these polymerbased FETs, throughout the range from insulating through semiconducting to metallic, through choices of doping levels and chemical manipulation of polymer side chains. A further advantage of doped PANi/PEO nanofibers is that they can be made to draw very small currents and operate at low voltage levels, and thus are promising for applications in which there are requirements to use many FETs to obtain large computational capabilities while minimizing power demands. Fabrication of an experimental FET in this family begins with the preparation of a substrate as follows: A layer of silicon dioxide between 50 and 200 nm thick is deposited on a highly doped (resistivity 0.01 W.cm) silicon substrate, then gold electrodes/contact stripes are deposited on the oxide. Next, one or more fibers of camphorsulphonic acid-doped PANi/PEO having diameters of the order of 100 nm are electrospun onto the substrate so as to span the gap between the gold electrodes (see Figure 1). Figure 2 depicts measured current-versus-voltage characteristics of the device of Figure 1, showing that saturation channel currents occur at source-todrain potentials that are surprisingly low, relative to those of CMOS FETs. The hole mobility in the depletion regime in this transistor was found to be 1.4 10(exp -4) sq cm/(V.s), while the one-dimensional charge density at zero gate bias was estimated to be approximately one hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content of the fibers is expected to enhance the properties of future versions of this transistor.

Theofylaktos, Noulie↗
NASA NTRS2010

Image Sensors Enhance Camera Technologies

In the 1990s, a Jet Propulsion Laboratory team led by Eric Fossum researched ways of improving complementary metal-oxide semiconductor (CMOS) image sensors in order to miniaturize cameras on spacecraft while maintaining scientific image quality. Fossum s team founded a company to commercialize the resulting CMOS active pixel sensor. Now called the Aptina Imaging Corporation, based in San Jose, California, the company has shipped over 1 billion sensors for use in applications such as digital cameras, camera phones, Web cameras, and automotive cameras. Today, one of every three cell phone cameras on the planet feature Aptina s sensor technology.

Source record↗
NASA NTRS2003

An Independent Human Factors Analysis and Evaluation of the Emergency Medical Protocol Checklist for the International Space Station

Emergency medical capabilities aboard the ISS include a Crew Medical Officer (CMO) (not necessarily a physician), and back-up, resuscitation equipment, and a medical checklist. It is essential that CMOs have reliable, usable and informative medical protocols that can be carried out independently in flight. The study evaluates the existing ISS Medical Checklist layout against a checklist updated to reflect a human factors approach to structure and organization. Method: The ISS Medical checklist was divided into non-emergency and emergency sections, and re-organized based on alphabetical and a body systems approach. A desk-top evaluation examined the ability of subjects to navigate to specific medical problems identified as representative of likely non-emergency events. A second evaluation aims to focus on the emergency section of the Medical Checklist, based on the preliminary findings of the first. The final evaluation will use Astronaut CMOs as subjects comparing the original checklist against the updated layout in the task of caring for a "downed crewmember" using a Human Patient Simulator [Medical Education Technologies, Inc.]. Results: Initial results have demonstrated a clear improvement of the re-organized sections to determine the solution to the medical problems. There was no distinct advantage for either alternative, although subjects stated having a preference for the body systems approach. In the second evaluation, subjects will be asked to identify emergency medical conditions, with measures including correct diagnosis, time to completion and solution strategy. The third evaluation will compare the original and fully updated checklists in clinical situations. Conclusions: Initial findings indicate that the ISS Medical Checklist will benefit from a reorganization. The present structure of the checklist has evolved over recent years without systematic testing of crewmember ability to diagnose medical problems. The improvements are expected to enable ISS Crewmembers to more speedily and accurately respond to medical situations on the ISS.

Marshburn, Thomas↗
NASA NTRS2004

Fabrication of Channels for Nanobiotechnological Devices

A method, now undergoing development, of forming nanochannels in planar substrates is intended to enable the fabrication of advanced fluidic devices that could be integrated with complementary metal oxide semiconductor (CMOS) electronic circuits. Such integral combinations of fluidic and electronic components ("laboratory-on-a-chip" devices) could be used, for example, to detect individual molecules of deoxyribonucleic acid (DNA) and proteins. The width of a channel in such a device would be chosen so that molecules of the species of interest would move along the channel in single file. In this method, the fabrication of channels includes the use of such CMOS-compatible processes as chemical-mechanical polishing and oxide deposition. The layout of the channels in the substrate plane is determined by a single photolithographic process, but it is not a nanoscale lithographic process, and this process is not relied upon to define the thickness and width of the channels. Stating it from a slightly different perspective, unlike in the prior fabrication of electronic and fluidic devices involving the use of lithography to define microscale features, this process does not include the use of lithography to define nanoscale features. It is this aspect of the method that enables simplification of the process and, hence, a decrease in cost.

Lee, Choonsup↗
NASA NTRS2004

Deep-Sea Video Cameras Without Pressure Housings

Underwater video cameras of a proposed type (and, optionally, their light sources) would not be housed in pressure vessels. Conventional underwater cameras and their light sources are housed in pods that keep the contents dry and maintain interior pressures of about 1 atmosphere (.0.1 MPa). Pods strong enough to withstand the pressures at great ocean depths are bulky, heavy, and expensive. Elimination of the pods would make it possible to build camera/light-source units that would be significantly smaller, lighter, and less expensive. The depth ratings of the proposed camera/light source units would be essentially unlimited because the strengths of their housings would no longer be an issue. A camera according to the proposal would contain an active-pixel image sensor and readout circuits, all in the form of a single silicon-based complementary metal oxide/semiconductor (CMOS) integrated- circuit chip. As long as none of the circuitry and none of the electrical leads were exposed to seawater, which is electrically conductive, silicon integrated- circuit chips could withstand the hydrostatic pressure of even the deepest ocean. The pressure would change the semiconductor band gap by only a slight amount . not enough to degrade imaging performance significantly. Electrical contact with seawater would be prevented by potting the integrated-circuit chip in a transparent plastic case. The electrical leads for supplying power to the chip and extracting the video signal would also be potted, though not necessarily in the same transparent plastic. The hydrostatic pressure would tend to compress the plastic case and the chip equally on all sides; there would be no need for great strength because there would be no need to hold back high pressure on one side against low pressure on the other side. A light source suitable for use with the camera could consist of light-emitting diodes (LEDs). Like integrated- circuit chips, LEDs can withstand very large hydrostatic pressures. If power-supply regulators or filter capacitors were needed, these could be attached in chip form directly onto the back of, and potted with, the imager chip. Because CMOS imagers dissipate little power, the potting would not result in overheating. To minimize the cost of the camera, a fixed lens could be fabricated as part of the plastic case. For improved optical performance at greater cost, an adjustable glass achromatic lens would be mounted in a reservoir that would be filled with transparent oil and subject to the full hydrostatic pressure, and the reservoir would be mounted on the case to position the lens in front of the image sensor. The lens would by adjusted for focus by use of a motor inside the reservoir (oil-filled motors already exist).

Cunningham, Thomas↗
NASA NTRS2011

Measuring Input Thresholds on an Existing Board

A critical PECL (positive emitter-coupled logic) interface to Xilinx interface needed to be changed on an existing flight board. The new Xilinx input interface used a CMOS (complementary metal-oxide semiconductor) type of input, and the driver could meet its thresholds typically, but not in worst-case, according to the data sheet. The previous interface had been based on comparison with an external reference, but the CMOS input is based on comparison with an internal divider from the power supply. A way to measure what the exact input threshold was for this device for 64 inputs on a flight board was needed. The measurement technique allowed an accurate measurement of the voltage required to switch a Xilinx input from high to low for each of the 64 lines, while only probing two of them. Directly driving an external voltage was considered too risky, and tests done on any other unit could not be used to qualify the flight board. The two lines directly probed gave an absolute voltage threshold calibration, while data collected on the remaining 62 lines without probing gave relative measurements that could be used to identify any outliers. The PECL interface was forced to a long-period square wave by driving a saturated square wave into the ADC (analog to digital converter). The active pull-down circuit was turned off, causing each line to rise rapidly and fall slowly according to the input s weak pull-down circuitry. The fall time shows up as a change in the pulse width of the signal ready by the Xilinx. This change in pulse width is a function of capacitance, pulldown current, and input threshold. Capacitance was known from the different trace lengths, plus a gate input capacitance, which is the same for all inputs. The pull-down current is the same for all inputs including the two that are probed directly. The data was combined, and the Excel solver tool was used to find input thresholds for the 62 lines. This was repeated over different supply voltages and temperatures to show that the interface had voltage margin under all worst case conditions. Gate input thresholds are normally measured at the manufacturer when the device is on a chip tester. A key function of this machine was duplicated on an existing flight board with no modifications to the nets to be tested, with the exception of changes in the FPGA program.

Kuperman, Igor↗
NASA NTRS2011

Multiple-Event, Single-Photon Counting Imaging Sensor

The single-photon counting imaging sensor is typically an array of silicon Geiger-mode avalanche photodiodes that are monolithically integrated with CMOS (complementary metal oxide semiconductor) readout, signal processing, and addressing circuits located in each pixel and the peripheral area of the chip. The major problem is its single-event method for photon count number registration. A single-event single-photon counting imaging array only allows registration of up to one photon count in each of its pixels during a frame time, i.e., the interval between two successive pixel reset operations. Since the frame time can t be too short, this will lead to very low dynamic range and make the sensor merely useful for very low flux environments. The second problem of the prior technique is a limited fill factor resulting from consumption of chip area by the monolithically integrated CMOS readout in pixels. The resulting low photon collection efficiency will substantially ruin any benefit gained from the very sensitive single-photon counting detection. The single-photon counting imaging sensor developed in this work has a novel multiple-event architecture, which allows each of its pixels to register as more than one million (or more) photon-counting events during a frame time. Because of a consequently boosted dynamic range, the imaging array of the invention is capable of performing single-photon counting under ultra-low light through high-flux environments. On the other hand, since the multiple-event architecture is implemented in a hybrid structure, back-illumination and close-to-unity fill factor can be realized, and maximized quantum efficiency can also be achieved in the detector array.

Zheng, Xinyu↗
NASA NTRS2012

ASIC Readout Circuit Architecture for Large Geiger Photodiode Arrays

The objective of this work was to develop a new class of readout integrated circuit (ROIC) arrays to be operated with Geiger avalanche photodiode (GPD) arrays, by integrating multiple functions at the pixel level (smart-pixel or active pixel technology) in 250-nm CMOS (complementary metal oxide semiconductor) processes. In order to pack a maximum of functions within a minimum pixel size, the ROIC array is a full, custom application-specific integrated circuit (ASIC) design using a mixed-signal CMOS process with compact primitive layout cells. The ROIC array was processed to allow assembly in bump-bonding technology with photon-counting infrared detector arrays into 3-D imaging cameras (LADAR). The ROIC architecture was designed to work with either common- anode Si GPD arrays or common-cathode InGaAs GPD arrays. The current ROIC pixel design is hardwired prior to processing one of the two GPD array configurations, and it has the provision to allow soft reconfiguration to either array (to be implemented into the next ROIC array generation). The ROIC pixel architecture implements the Geiger avalanche quenching, bias, reset, and time to digital conversion (TDC) functions in full-digital design, and uses time domain over-sampling (vernier) to allow high temporal resolution at low clock rates, increased data yield, and improved utilization of the laser beam.

Vasile, Stefan↗
NASA NTRS2012

Development of Two Color Fluorescent Imager and Integrated Fluidic System for Nanosatellite Biology Applications

Nanosatellites offer frequent, low-cost space access as secondary payloads on launches of larger conventional satellites. We summarize the payload science and technology of the Microsatellite in-situ Space Technologies (MisST) nanosatellite for conducting automated biological experiments. The payload (two fused 10-cm cubes) includes 1) an integrated fluidics system that maintains organism viability and supports growth and 2) a fixed-focus imager with fluorescence and scattered-light imaging capabilities. The payload monitors temperature, pressure and relative humidity, and actively controls temperature. C. elegans (nematode, 50 m diameter x 1 mm long) was selected as a model organism due to previous space science experience, its completely sequenced genome, size, hardiness, and the variety of strains available. Three strains were chosen: two green GFP-tagged strains and one red tdTomato-tagged strain that label intestinal, nerve, and pharyngeal cells, respectively. The integrated fluidics system includes bioanalytical and reservoir modules. The former consists of four 150 L culture wells and a 4x5 mm imaging zone the latter includes two 8 mL fluid reservoirs for reagent and waste storage. The fluidic system is fabricated using multilayer polymer rapid prototyping: laser cutting, precision machining, die cutting, and pressure-sensitive adhesives it also includes eight solenoid-operated valves and one mini peristaltic pump. Young larval-state (L2) nematodes are loaded in C. elegans Maintenance Media (CeMM) in the bioanalytical module during pre-launch assembly. By the time orbit is established, the worms have grown to sufficient density to be imaged and are fed fresh CeMM. The strains are pumped sequentially into the imaging area, imaged, then pumped into waste. Reagent storage utilizes polymer bags under slight pressure to prevent bubble formation in wells or channels. The optical system images green and red fluorescence bands by excitation with blue (473 nm peak) and amber (587 nm peak) LEDs it achieves 8 m lateral resolution using a CMOS imaging chip (as configured for serial data speeds) or 4 m resolution using USB imaging chips. The imager consists of a modified commercial off-the-shelf CMOS chip camera, amber, blue and white LEDs, as well as a relay lens and dual-band filters to obviate moving parts while supporting both fluorescence wavelengths.

Wu, Diana Terri↗
NASA NTRS2020

Nonlinear Microwave Interactions with Voltage-Gated Graphene Devices

In this dissertation, methods of fabrication and testing micro- and nano-scaled thermoelectric microwave power detectors based on graphene are explored. Initial detectors show sensitivities of 0.87 mV/mW and each chapter herein describes the iterations and improvements made to the devices. In the end, detectors have shown sensitivities of up to 60.25 mV/mW when accounting for the reflection coefficient of the device, over a 690% increase in sensitivity. Commercially-available detectors that feature zero DC power consumption and operate over similar frequency ranges typically over a power detection sensitivity of 500 mV/mW. However, state-of-the-art thermoelectric detectors based on CMOS and MEMS technologies over power detection sensitivities that are typically lower than 0.4 mV/mW. Unoptimized graphene based detectors have been shown to outperform CMOS and MEMS detectors. An outlook is provided on further optimizations that can be made to the devices.

Michael Robert Gasper↗
NASA NTRS2009

Commercial Sensor Survey Fiscal Year 2009 master compendium radiation test report

The NASA Electronic Parts and Packaging (NEPP) Program Sensor Technology Commercial Sensor Survey task is geared toward benefiting future NASA space missions with low-cost, short-duty-cycle, visible-wavelength imaging needs. Such applications could include imaging for educational outreach purposes or short surveys of spacecraft, planetary, or lunar surfaces. Under the task, inexpensive, low-power, commercial grade CMOS sensors were surveyed in fiscal year 2007 (FY07), and three sensors were selected and tested for total ionizing dose (TID) and displacement damage dose (DDD) tolerance in fiscal year 2008 (FY08). The selected sensors had to meet selection criteria chosen to support small, low-mass cameras that produce good resolution color images. The commercial CMOS sensors tested under the task in FY08 showed very promising response to typical outreach and survey camera TID and DDD levels. In fiscal year 2009 (FY09), the survey was broadened to include two additional, similar sensor products. This compendium provides results for all radiation testing performed on the Micron and OmniVision sensors that were selected for radiation tolerance testing in FY08 and FY09.

Thorbourn, Dennis O.↗
NASA NTRS2018

Context Cameras for the Orbiting Carbon Observatory 3 (OCO-3) Instrument

We have developed an adaptable camera platform that takes advantage of screened and qualified commercial off the shelf (COTS) components (CMOS sensor, rad-tolerant microcircuits, lenses) to significantly shorten development time of space-borne visible imaging systems while reducing the overall cost and risk of the development. This modular camera platform is implemented as a suite of two visible-light cameras for the Orbiting Carbon Observatory 3 (OCO-3) instrument at NASA’s Jet Propulsion Laboratory (JPL). The Internal Context Camera (ICC) and External Context Camera (ECC) provide contextual engineering imaging support for the calibration of the OCO-3 instrument, intended to significantly reduce the duration of the mission’s calibration campaign. The OCO-3 mission has taken advantage of the design and qualification work performed by JPL’s Mars 2020 Enhanced Engineering Camera (EECam) team in reusing the qualified COTS CMOS imaging sensor, proven electronic designs, and scalable field-programmable gate array (FPGA) firmware to meet OCO-3’s mission requirements and resource availability. We will be presenting the steps taken by JPL to design, build, and test the Context Cameras for the OCO-3 mission. We will highlight the design deviations from the Mars2020 EECams and discuss the methodology of tailoring the EECam design for the OCO-3 requirements. Camera imaging capabilities, including focal plane and optical performance, will be presented, as well as a summary of the calibration and environmental test results. Finally, we will discuss the potential for future applications for the Context Cameras.

Moore, Douglas↗
NASA NTRSDate not supplied

AstroPix: ATLAS-Inspired Silicon Pixels for Future Space-Based Gamma-ray Telescopes

Space-based gamma-ray telescopes such as the Fermi Large Area Telescope have used single sided silicon strip detectors to measure the position of incident gamma-rays with high resolution. At lower energies, two dimensional position information within a single detector is required. This talk investigates the use of monolithic CMOS active pixel silicon sensors –AstroPix – as a novel technology for use in future gamma-ray telescopes. Based upon detectors designed for use in the ATLAS detector at the LHC, AstroPix has the potential to maintain the high energy and angular resolution required of a medium-energy gamma-ray telescope while reducing noise with the dual detection and readout capabilities of a CMOS chip. The status of AstroPix development and testing, as well as outlook for application in future telescopes such as the proposed medium-energy gamma-ray telescope AMEGO-X, will be presented.

Amanda L. Steinhebel↗
NASA NTRSDate not supplied

Harnessing Artificial Intelligence for Medical Diagnosis and Treatment During Space Exploration Missions

From May 8th to June 9th, 2023, I had the opportunity to participate in an experiential learning experience at Johnson Space Center in Houston, TX with Exploration Medical Capability (ExMC), an element of the NASA Human Research Program. During this research experience, I was not only able to work on the above titled research project, but also gain an immense exposure to the field of aerospace medicine, make numerous connections within the field, tour NASA facilities, as well as travel to the Aerospace Medical Association Annual Conference (AsMA) in New Orleans. To briefly introduce my project, it is well understood that the medical capabilities available to crew medical officers (CMOs) on the International Space Station will be different than the capabilities available and needed during deep space exploration missions to the Moon, Mars, and beyond. Ground support is particularly limited due to distance, communication delays (or lack of communication), and lack of resupply. Therefore, to support medical care by CMOs on these missions, robust clinical decision support systems (CDSSs) must be designed. The recent publication and public launch of generative artificial intelligence (AI) tools based upon large language models (LLM) such as ChatGPT provides the opportunity to create a smart assistant for onboard triage, diagnosis, and treatment of medical conditions. Ultimately, the overall purpose of the project was to research what AI tools currently exist or are in development, and to see how they might be implemented onboard during exploration class spaceflights of the future. The ExMC element is actively developing several tools to be used in preparation for and during deep space exploration missions. One of those tools, known as IMPACT, is a probabilistic risk assessment model which can be used to propose a desired medical system (based on mass and volume) and suggest the clinical outcomes likely to occur for a design reference mission (DRM). The group recently presented the IMPACT model and a DRM of interest titled “Modified Long Duration Lunar Orbital and Lunar Surface” (mLDLOLS) at the recent AsMA conference. The mLDLOLS mock mission is a 9 month and 6-day deep space exploration mission consisting of time in Moon’s orbit (3 months on the Gateway space station), on the lunar surface (3 months within habitat), and another 3 months on Gateway before return to Earth. For this DRM, IMPACT ultimately outlined a preferred medical system that was then associated with medical conditions considered to be most likely based on frequency, most likely to cause astronaut task time loss (TTL), most likely to cause return to definitive care (RTDC), and most likely cause loss of crew life (LOCL). IMPACT also highlighted the medical capabilities/skills that would be required to care for those medical conditions, such as performing a history of present illness or musculoskeletal exam with ultrasound. The primary objective of the project was to perform a survey of the AI tools and systems applicable to the conditions outlined for the proposed mLDLOLS mission. Using PubMed (including most relevant MeSH terms) and Google Scholar, we then created a robust annotated bibliography organized by condition. The 56-page and over 500 reference annotated bibliography was subsequently used to create a review outline that would become the basis for drafting of a future publication. For the review outline, we took those medical conditions researched within the annotated bibliography (condition-based approach) and deployed a systems-based approach, combining those medical conditions and related tools into ten categories. These categories included general/all-purpose CDSSs, tools to diagnose or manage respiratory, dermatologic, neurologic, auditory and vestibular, ophthalmic, musculoskeletal, infection-associated, and gynecologic conditions, as well as tools that could be deployed in the setting of trauma/emergency. With the completion of the 30-page outline, we then began drafting the review paper. To conclude the research experience, I presented the findings from our survey to the ExMC Clinical and Science team. With these objectives, I ultimately learned about the number of AI tools that exist today to assist medical professionals with the triage, diagnosis, and management of several medical conditions. These tools can span from chatbot assistants to help triage knee pain to vision transformer models that can identify ophthalmic conditions based on ocular surface images captured with a cell phone. We also highlighted the current gaps that exist in the literature alongside the advancements that are needed to make the desired CDSS for deep space exploration missions. With this experience, I certainly confirmed an existing career goal and identified several additional skills needed to become an aerospace medical doctor including knowledge of critical care in an extreme medicine setting, aerospace engineering and human integration systems, artificial intelligence, machine learning, and risk models. I also identified numerous transferable skills for this career goal including the basic knowledge of medicine (MD), deployment of the scientific method for critical thought about new scientific questions (PhD), review of published literature, including creating an annotated bibliography (PhD), as well as detailed scientific writing (PhD). The results of my research will likely guide the design of an all-encompassing onboard medical assistant for use during deep space exploration missions of the future. I plan on sharing the outcomes from this experience with my peers at a student seminar in the Fall semester on August 30th. During the seminar, I will detail the project, my experience at NASA and AsMA, as well as offer best practice guidelines for students entertaining similar experiences or careers. In conclusion, I would like to thank the WVU School of Medicine, Research and Graduate Education office, as well as NASA ExMC for the unwavering support of this life-changing experience.

Ryan A. Lacinski↗
DOE OSTI2020

A Sub-Threshold Low-Power Integrated Bandpass Filter for Highly-Integrated Spectrum Analyzers

Low-power analog filter banks provide frequency analysis with minimal power and space requirements, making them viable solutions for integrated remote audio- and vibration-sensing applications. Compared with their digital counterparts, analog filter banks are better suited to achieve the lower power consumption necessary for IoT applications, while maintaining high dynamic range and a wide operational frequency range. In this work, the design and implementation of a sub-threshold complementary metal-oxide semiconductor (CMOS) integrated low-power tunable analog filter channel for signal spectrum analysis and signal discrimination is presented. Project specifications required a programmable, high-order, monolithic bandpass filter channel with small chip area, low power consumption, high dynamic range, and wide operational frequency range. The 8th-order filter channel presented in this work provides an effective Q-factor of 4.5 and a minimum dynamic range (DR) of approximately 85 dB, while allowing for tuning across a range of center frequencies from 2 kHz to 100 kHz, with power consumption of a single 8th-order filter channel measured at 256 µW nominally at the highest center frequency. An integrated analog Gm-C filter topology was selected for this application. Functionally, the high-Q bandpass filter transfer function is implemented via four cascaded 2nd-order filter cells, resulting in a single 8th-order filter channel, fabricated in 130-nm 1.2-V CMOS technology, suitable for use in monolithic integrated spectral analysis (MISA1) applications.

Long, Gavin B.↗
DOE OSTI2020

A Sub-Threshold Low-Power Integrated Bandpass Filter for Highly-Integrated Spectrum Analyzers

Low-power analog filter banks provide frequency analysis with minimal power and space requirements, making them viable solutions for integrated remote audio- and vibration-sensing applications. Compared with their digital counterparts, analog filter banks are better suited to achieve the lower power consumption necessary for IoT applications. In this work, the design and implementation of a sub-threshold complementary metal-oxide semiconductor (CMOS) integrated low-power tunable bandpass filter channel for signal spectrum analysis and signal discrimination is presented, including performance improvements to stability and precise matching between filter stages. The 8 th -order filter channel achieves an effective Q-factor of 4.5 and dynamic range of 60 dB, has an operational frequency range from 2 kHz to 100 kHz, and consumes 256 µW nominally at the highest center frequency. An integrated analog Gm-C filter topology is selected for this application. Functionally, the high-Q bandpass filter transfer function is implemented via four cascaded 2 nd -order filter cells and is fabricated in 130-nm 1.2-V CMOS technology, making it suitable for use in monolithic integrated spectral analysis (MISA) applications.

Long, Gavin↗
DOE OSTI2021

Final Report for Grant

This is the final report for this project. The major objectives were to develop full models and standard cells of CMOS silicon photomultipliers (SiPM) for neutron detection applications. Specifically, the research seeks to replace photomultiplier tubes, used in neutron detection applications, with SiPMs containing integrated readout electronics fabricated in standard CMOS processes. The detectors improve on the detection efficiency, readout speed, resolution (sensitivity), and spatial resolution of current systems. In particular, this work involved collaboration with the instrument and detector group at ORNL who build detectors based on discrete commercially available PMTs and SiPMs. The SiPM detectors developed in this work are based on Perimeter Gated Single Photon Avalanche Diodes (PGSPAD). These devices have tunable breakdown voltage which affects other performance characteristics of the detectors. The ability of the detectors to have integrated readout and tune the noise floor and dynamic range in addition to offering a method for non-uniformity compensation in a compact form significantly impacts the imaging research field and includes the nuclear sciences field, circuits and systems field in addition to varied fields such as geography and biology/medicine.

42 ENGINEERING↗
DOE OSTI2023

Piezoelectric deformable photonic devices

A CMOS-compatible actuator platform for implementing phase, amplitude, and frequency modulation in silicon nitride photonic integrated circuits via piezo-optomechanical coupling using tightly mechanically coupled aluminum nitride actuators is disclosed. The platform, which may be fabricated in a CMOS foundry, enables scalable active photonic integrated circuits for visible wavelengths, and the piezoelectric actuation functions without performance degradation down to cryogenic operating temperatures. A number of devices are possible, including ring modulator devices, phase shifter devices, Mach-Zehnder interferometer devices, directional coupler devices (including tunable directional coupler devices), and acousto-optic modulator and frequency shifter devices, each of which can employ the same AlN actuator platform. As all of these devices can be built on the same AlN actuator platform, numerous optical functions can be implemented on a single die.

Eichenfield, Matt↗