Compact Package Research Articles

The Simons Observatory 220 and 280 GHz Focal-Plane Module: Design and Initial Characterization

The Simons Observatory (SO) will detect and map the temperature and polarization of the millimeter-wavelength sky from Cerro Toco, Chile across a range of angular scales, providing rich data sets for cosmological and astrophysical analysis. The SO focal planes will be tiled with compact hexagonal packages, called Universal Focal-plane Modules (UFMs), in which the transition-edge sensor (TES) detectors are coupled to 100 mK microwave-multiplexing electronics. Three different types of dichroic TES detector arrays with bands centered at 30/40, 90/150, and 220/280 GHz will be implemented across the 49 planned UFMs. The 90/150GHz and 220/280 GHz arrays each contain 1,764 TESes, which are read out with two 910x multiplexer circuits. The modules contain a series of densely routed silicon chips, which are packaged together in a controlled electromagnetic environment with robust heat-sinking to 100 mK. Following an overview of the module design, we report on early results from the first 220/280GHz UFM, including detector yield, as well as readout and detector noise levels.

Built-In Packaging for Single Terminal Devices.

An alternative packaging method, termed built-in packaging, is proposed for single terminal devices, and demonstrated with an actuator application. Built-in packaging removes the requirements of wire bonding, chip carrier, PCB, probe station, interconnection elements, and even wires to drive single terminal devices. Reducing these needs simplifies operation and eliminates possible noise sources. A micro resonator device is fabricated and built-in packaged for demonstration with electrostatic actuation and optical measurement. Identical actuation performances are achieved with the most conventional packaging method, wire bonding. The proposed method offers a compact and cheap packaging for industrial and academic applications.

High Energy Density Carbon Nanotube-Based Supercapacitors

We have developed supercapacitors utilizing electrodes made of binder-free carbon nanotube (CNT) / activated carbon (AC) composites. Due to the absence of organic binder our supercapacitors exhibit a significantly higher volumetric capacitance of ~20 F/cc compared to conventional supercapacitors while maintaining low resistance. This results in higher energy in the same package or smaller, more compact package size (lower volume) with same energy. Our cells pass 1,000 hour float tests at 2.7V between -35°C and 70°C, as well as high voltage operation at 3V and 70°C. Operation for 100,000 continuous cycles at 85°C was also achieved. Flat format supercapacitor pouch cells > 100 F have been demonstrated that can be integrated into automotive panels for autonomous power. Notable features of our CNT/AC composite supercapacitor technology include: Scalable R2R coating of CNT/AC electrodes without additives. Option of water-based process with no solvent recoveryBinder-free CNT/AC electrodes provide 20% higher energy density than conventional AC-based electrodes (50% higher energy density at 3V)CNT/AC supercapacitor technology is 100% packaging agnosticFabrication of 18650 EDLC cells rated at ~ 100 F demonstrated, and pouch cells rated at ~ 350 F demonstrated The flat pouch-cell format allows installation in automotive panels as power sources for emergency door lock/unlock applications. Figure 1

Hybrid nanofluid spray cooling performance and its residue surface effects: Toward thermal management of high heat flux devices

• Hybrid nanofluid spray system.shows critical heat flux enhancement up to 126%. • Critical heat flux enhancement may be due to residue wetting and wicking effects. • Hybrid nanofluid sprays show higher heat transfer coefficient than existing fluids. • Existing fluid sprays fail to effectively cool electric vehicle power electronics. • Hybrid nanofluid sprays can effectively cool electric vehicle power electronics. In recent years, heat dissipation in high heat flux devices remarkably increased and it is anticipated to reach unprecedented levels in future devices, mainly due to increased power density, compact packaging and high-performance requirements. To address this challenge, in current research, we initially investigate the spray cooling performance and spray residue surface effects of the next generation thermal fluid, called hybrid nanofluid. Subsequently, we investigate the hybrid nanofluid spray cooling potential to address heat dissipation issues in a high heat flux application, that is, the electric vehicle (EV) high power electronics. Our results demonstrate that the critical heat flux (CHF) enhancement up to 126% can be achieved using the hybrid nanofluid spray cooling compared to water spray cooling. The hybrid nanofluid and its spray residue characterization further suggest that high CHF in hybrid nanofluid spray cooling may be due to high latent heat of vaporization and residue wetting and wicking effects. Moreover, the spray cooling efficiency and Nusselt number obtained for hybrid nanofluid spray cooling is more than twice that of water spray cooling. Furthermore, our results indicate that the hybrid nanofluid spray cooling can keep high power electronics of current and future electric vehicles below their failure temperatures, while the same cannot be achieved using water and dielectric fluid spray cooling.

Radioactive Waste Embedding in Cement Matrix and the Establishment of Cemented Waste Testing Laboratory at Paks Nuclear Power Plant

For the treatment of low and intermediate level radioactive wastes generated at the Nuclear Power Plant of Paks, a new compact waste package will be created with a new cementation technology currently under construction. During the operation, the solid waste will be placed in steel drums, which then will be put into a thin-walled steel container. The cavity volume of the containers will be filled with cemented slurry made using liquid radioactive waste. The compact waste packages must comply with the waste acceptance criteria described in the National Radioactive Waste Repository Safety Report. The task of the cemented waste testing laboratory, which is under construction, will be the in-service inspection of the finished cemented material and the determination of properties such as compressive strength and leachability (diffusion coefficient) of the specimens made thereof. During the installation of the laboratory and testing of the devices used in the cement / concrete industry, it turned out that in many cases special moulds are required due to the low viscosity and corrosive properties of the radioactive paste. In addition, the collection of debris generated during the measurement of compressive strength of radioactive cement stone and the minimization of dusting are important requirements.

Resource allocation applied to flexible printed circuit routing based on constrained Delaunay triangulation

Flexible printed circuit (FPC) are widely used as connectors in compact package such as cellular telephones where required high performance. The increasing number of constrains makes manual routing an extremely complicated and time-consuming task. In this paper, we present a resource allocation framework which employs computational geometry considering signal and power integrity (SI/PI). To perform a reasonable resource allocation, we propose an escape-triangle-passage model (ETP model) based on constrained Delaunay triangulation (CDT). Experimental results on some industrial data show our strategy assembled routing channel for each group of nets has good robustness and is suitable for irregular polygonal routing region, significantly improving the routing quality and reducing iteration times.

QuadPlus: Design, Modeling, and Receding-Horizon-Based Control of a Hyperdynamic Quadrotor

The maneuverability of standard quadrotors with coplanar propellers is limited by their inherent underactuation. To overcome this challenge, in-flight, active propeller tilting has been widely investigated in the literature. However, biaxial propeller tilting that renders extensive thrust vectoring has not been explored much owing to the ensuing mechanical complexities. Therefore, this article presents an innovative design capable of achieving independent biaxial tilting of $\text{100}^\circ$ and $\text{180}^\circ$ about two perpendicular axes while keeping the mechanical complexity relatively low. The developed quadrotor, aptly named QuadPlus, efficiently combines actuator redundancy and propeller rotation in a compact package, compared to its state-of-the-art counterparts. The hyperdynamic QuadPlus with a total of 12 degrees of freedom can control its attitude independent of the position, thus enabling effective maneuvering through narrow spaces. Moreover, a novel cascade approach comprising of a high-level nonlinear model-predictive control algorithm is adopted to obtain the optimal actuator configuration for an underdetermined system while dealing with the physical constraints. In addition, proportional–integral–derivative controllers are employed at low level to track attitude references generated by the navigation algorithm. Finally, with the help of realistic Gazebo simulations, the efficacy of the system is demonstrated by tracking complex 3-D trajectories, which replicate the motion in a constrained environment. Overall, the obtained results manifest QuadPlus’s capability of achieving independent position and attitude control even with multiple actuator saturation. The authors envision that the proposed simplistic design would stimulate interest in the community for exploring the benefits offered by biaxial propeller tilting platforms.

Series Active Variable Geometry Suspension: Full-Car Prototyping and Road Testing

In this article, a full-car prototype of the recently proposed mechatronic suspension, series active variable geometry suspension (SAVGS), is developed for the on-road driving experimental proof of concept, aiming to be adopted by suspension original equipment manufacturers as an alternative solution to fully active suspensions. Particularly, mechanical modifications are performed to both corners of the front double-wishbone suspension of a production car with active single link attached to the upper ends of the spring–damper units, while both corners of the rear suspension remain in the original (passive) configurations. The mechanical modifications involve innovatively designed parts to enable the desired suspension performance improvements while maintaining ride harshness at the conventional levels. A real-time embedded system is further developed to primarily implement power supply, data acquisition, and measurements of the vehicle dynamics-related variables, and robust control application for the ride comfort and road holding enhancement, which is based on a derived linearized model of the full-car dynamics and a newly synthesized H-infinity control scheme. The results obtained from the on-road driving experiments are in essential agreement with numerical simulation results also produced. Overall, the full-car prototype of SAVGS demonstrates promising suspension performance with an average 3 dB attenuation (or equivalently 30% reduction) of the chassis vertical acceleration at around the human-sensitive frequencies (2–5 Hz), as compared with the original vehicle with the passive suspension system. More importantly, the prototype also indicates the practicality of the solution, as the SAVGS retrofit to a real car is achieved by simple mechanical modifications, compact actuator packaging, small mass increment (21.5 kg increase with respect to the original vehicle), limited power usage (an average value of 134 W in dc batteries with a Class D random road), and acceptable economic cost.

Highly heat-resistant NF membrane modified by quinoxaline diamines for Li+ extraction from the brine

The Functional layers with excellent heat-resistence nanofiltration (HRN) property were designed by fixing thermal stabilized quinoxaline diamines (QHDA) on poly (m-phenyleneisophthalamide) (PMIA) substrate through interfacial polymerization. QHDA was used as aqueous monomer while cinnamoyl chloride (CNC), isophthaloyl chloride (IPC) and trimesoyl chloride (TMC) were served as organic monomers to realize the immobilization of thermally stable N heterocycles. The experimental results stated clearly that the compact package reaction of QHDA with TMC lead a raise of thermal stability and salts rejection at high temperature stream. With the optimal TMC and 0.5 wt.% QHDA, the as-developed membrane achieved the excellent NF performance and thermal stability. The rejection of MgSO4 reached to 94.6 % at 30 °C and hardly decrease at 90 °C. The reduction in rejection was satisfactory at high temperatures. The functional layer still showed highly stability after 10 h long-term operation at 90 °C with only 2.8 % reduction in MgSO4 rejection. Besides, the excellent Mg2+ and poor Li+ rejection made this membrane have huge potential in the application of extracting Li+ from brine. The separation factor of Mg2+-Li+ at high temperature was satisfactory. Over all, this study offered a prospect technology to exploit heat-resistant membranes for extraction lithium at high temperature.

Lateral spectrum splitting system with perovskite photovoltaic cells

We examine the potential of a multijunction spectrum-splitting photovoltaic (PV) solar energy system with perovskite PV cells. Spectrum splitting allows combinations of different energy band gap PV cells that are laterally separated and avoids the complications of fabricating tandem stack architectures. Volume holographic optical elements have been shown to be effective for the spectrum-splitting operation and can be incorporated into compact module packages. However, one of the remaining issues for spectrum splitting systems is the availability of low-cost wide band gap and intermediate band gap cells that are required for realizing high overall conversion efficiency. Perovskite PV cells have been fabricated with a wide range of band gap energies that potentially satisfy the requirements for multijunction spectrum-splitting systems. A spectrum-splitting system is evaluated for a combination of perovskite PV cells with energy band gaps of 2.30, 1.63, and 1.25 eV and with conversion efficiencies of 10.4%, 21.6%, and 20.4%, respectively, which have been demonstrated experimentally in the literature. First, the design of a cascaded volume holographic lens for spectral separation in three spectral bands is presented. Second, a rigorous coupled wave model is developed for computing the diffraction efficiency of a cascaded hologram. The model accounts for cross-coupling between higher diffraction orders in the upper and lower holograms, which previous models have not accounted for but is included here with the experimental verification. Lastly, the optical losses in the system are analyzed and the hypothetical power conversion efficiency is calculated to be 26.7%.

Design and Assist-As-Needed Control of a Lightly Powered Prosthetic Knee

This paper presents the design of a swing-assist prosthetic knee capable of providing stabilizing passive torques during the stance phase of walking and supplementing the passive swing phase behavior of the prosthetic knee with small active torques. The prosthesis design utilizes a novel actuator which integrates a symmetric multi-chamber hydraulic cylinder and a highly backdrivable linear electromechanical drive system into a single compact package. This actuator is implemented in a self-contained prosthesis design (including batteries and embedded system) which weighs 1.7 kg and is 28 cm in length, making this design comparable in size/mass to commercially available microprocessor-controlled prosthetic knees. The device is controlled using a finite state machine with a novel assist-as-needed controller operating during the swing phase. This assist-as-needed controller supplements a nominally passive swing phase behavior with small amounts of active power to enhance user safety. The device and controller were assessed on a single participant who took part in level ground walking experiments with both the swing-assist prosthesis and his daily-use device. Results indicate that the swing-assist prosthesis increases maximum swing phase knee flexion angle relative to the subject’s daily-use device. Furthermore, the swing-assist prosthesis was shown to automatically vary its assistance across walking speeds.

Folding arrays of uniform-thickness panels to compact bundles with a single degree of freedom

Flat arrays consisting of panels of finite thickness are widely used in aerospace applications such as solar panels and reflectarray antennas. Packaging them into compact bundles without any voids and then deploying them bi-directionally to flat, continuous and accurate surfaces with a single degree of freedom (DoF) has challenged engineers for decades. Here, we present a solution based on origami of thick panels. In modular construction, we first created two deployable unit arrays, each of which comprises four eight-panel elements where panels in regular shapes are connected by simple but robust rotational joints. We prove that these units have only a single DoF, and they can be folded from a flat array to compact bundles without any voids. We then show that the units can be tessellated to form larger flat arrays where a single-DoF deployment and compact packaging properties are intact. A parametric study is carried out, which provides a precise design range that prevents the panels from physical interference during deployment. Physical models were constructed that have successfully validated the concepts. Our work is directly applicable to the design of future flat arrays that can be controlled with ease.

Miniaturized Sensors for Detection of Ethanol in Water Based on Electrical Impedance Spectroscopy and Resonant Perturbation Method—A Comparative Study

The development of highly sensitive, portable and low-cost sensors for the evaluation of ethanol content in liquid is particularly important in several monitoring processes, from the food industry to the pharmaceutical industry. In this respect, we report the optimization of two sensing approaches based on electrical impedance spectroscopy (EIS) and complementary double split ring resonators (CDSRRs) for the detection of ethanol in water. Miniaturized EIS sensors were realized with interdigitated electrodes, and the ethanol sensing was carried out in liquid solutions without any functionalization of the electrodes. Impedance fitting analysis, with an equivalent circuit over a frequency range from 100 Hz to 1 MHz, was performed to estimate the electric parameters, which allowed us to evaluate the amount of ethanol in water solutions. On the other hand, complementary double split ring resonators (CDSRRs) were optimized by adjusting the device geometry to achieve higher quality factors while operating at a low fundamental frequency despite the small size (useful for compact electronic packaging). Both sensors were found to be efficient for the detection of low amounts of ethanol in water, even in the presence of salts. In particular, EIS sensors proved to be effective in performing a broadband evaluation of ethanol concentration and are convenient when low cost is the priority. On the other end, the employment of split ring resonators allowed us to achieve a very low limit of detection of 0.2 v/v%, and provides specific advantages in the case of known environments where they can enable fast real-time single-frequency measurements.

The Impact of Head and Neck Multidisciplinary Clinic on Treatment Package Time During the COVID-19 Pandemic: A Single Institutional Experience

Purpose/Objective(s)The onset of the COVID-19 pandemic in the United States has had a profound impact on the delivery of medical care in this country, particularly in the outpatient clinical setting. A result of the pandemic has been the introduction of delays in the diagnosis and treatment of head and neck cancer which are strongly associated with inferior oncologic outcomes. Efforts to minimize these delays are therefore a high priority in this patient population. Here, we report the results from one particular intervention taken at our institution - the formation of a multidisciplinary clinic (MDC) - on treatment times.Materials/MethodsIn July 2020, our institution initiated a pilot program establishing a MDC combining otolaryngology and radiation oncology visits. Clinics were held on a half-day every two weeks and consisted of both new patient consults and follow-up patients who had received radiation as part of their treatment course. We measured and compared treatment package time of the MDC patients with those seen at our institution in the standard clinic setting.ResultsA total of 25 new patients requiring radiation were seen in our MDC between 7/31/2020 and 9/3/2021. This included 8 patients who underwent definitive radiation, 12 patients who underwent adjuvant radiation, and 5 patients who underwent palliative radiation. A total of 54 patients received radiation through standard clinics during this time frame, with 21 definitive cases, 28 adjuvant cases, and 5 palliative cases. There was no difference in median radiotherapy duration between the patients seen in MDC vs standard clinics (41 vs 41 days, p = NS). In comparison, however, the patients seen in MDC started adjuvant radiotherapy sooner (median 34 vs 41.5 days, p=0.002) and had a more compact treatment package times (median 76.5 vs 84.5 days, p=0.002). Three patients in the standard clinics cohort had treatment package times exceeding 100 days while no patient seen in MDC had a treatment package time exceeding 84 days.ConclusionDespite the many challenges associated with the ongoing COVID-19 pandemic, we found that patients seen in our MDC setting maintained timely treatment package times that were significantly better than those seen in our standard clinics. This is potentially due to the identification of patients likely to require adjuvant radiotherapy earlier in their clinical presentation. This in turn allowed for more advanced planning and minimization of delays in initiation of adjuvant radiotherapy. While previous studies have demonstrated improved oncologic outcomes when head and neck multispecialty care is delivered at tertiary care facilities, we found a further improvement in care delivery with colocalization of clinic visits by the treatment team.

Drive to Squeeze More Power From Tiny Packages, On-Chip Substrates Continues Unabated [From the Editor

The fervor for miniaturization continues in the power supply world. Power supply designers have kept pace with the demands of the market for more power from smaller packages with better efficiency, reliability, and speed. While keeping the cost low. Consequently, power integration, both in package and on-chip, has continued to evolve for more than a decade. The result is that power supply in package (PSiP) and power supply on-chip (PwrSoC) have become mainstream products, driven by traditional and emerging applications. Today, we are talking about hundreds of watts from a compact semiconductor package, as well monolithic semiconductor substrates.

Driven by Density, Efficiency at Low Cost, Power Integration Reaches New Heights: PSiPs and PwrSoCs are growing faster than the traditional power supplies

For decades, miniaturization has been the trend in the power supply world. Consumers have been demanding more functions from smaller systems with better performance and reliability at lower cost. Such advances are evident in today’s laptops, tablets, smartphones, industrial drives and a host of other consumer and industrial applications. To meet these demands, the power supply industry has also kept pace with the needs of the markets. As a result, power integration, both in package and on-chip, has continued to evolve for more than a decade. Consequently, with this evolution, power density has risen from tens of watts to hundreds of watts from compact semiconductor packages with high performance in efficiency, density, reliability and other such metrics. On-chip, we are talking about tens of watts delivered from monolithic semiconductor substrates.

Folding and deploying identical thick panels with spring-loaded hinges

Many large deployable flat rigid arrays for aerospace applications, e.g., solar panels and reflectarray antennas, are preferably made from identical panels. It is challenging to pack them into a compact bundle before launching and deploy to a flat surface once in the orbit, especially if they are having bi-directional deployments. In this paper, we propose a folding scheme based on the Hamiltonian circuit that can successfully fold a chessboard-like array into a compact package with two stacks of panels without any voids. Since this approach leads to a multiple degrees-of-freedom (DoFs) assembly kinematically, simple spring-loaded hinges are used to synchronise the deployment. An effective optimisation method is subsequently proposed to select the stiffness of rotational joints to ensure a collision-free deployment. Dynamic simulation of the deployment and a collision detection method are incorporated into the optimisation process. By this approach, the trajectories of panels are sequenced to avoid collisions during the deployment, and the array always deploys to a flat surface from packaged stacks. Both the folding schemes and subsequent deployments were validated successfully by experiments. Though we consider only rectangular panels here, the approach can be extended to deployable arrays of any regular shape.

Development of Inspired Therapeutics Pediatric VAD: Computational Analysis and Characterization of VAD V3

Pediatric heart failure patients remain in critical need of a dedicated mechanical circulatory support (MCS) solution as development efforts for specific pediatric devices continue to fall behind those for the adult population. The Inspired Pediatric VAD is being developed as a pediatric specific MCS solution to provide up to 30-days of circulatory or respiratory support in a compact modular package that could allow for patient ambulation during treatment. Hydrodynamic performance (flows, pressures), impeller/rotor mechanical properties (torques, forces), and flow shear stress and residence time distributions of the latest design version, Inspired Pediatric VAD V3, were numerically predicted and investigated using computational fluid dynamics (CFD) software (SolidWorks Flow Simulator). Hydrodynamic performance was numerically predicted, indicating no change in flow and pressure head compared to the previous device design (V2), while displaying increased impeller/rotor torques and translation forces enabled by improved geometry. Shear stress and flow residence time volumetric distributions are presented over a range of pump rotational speeds and flow rates. At the lowest pump operating point (3000 RPM, 0.50 L/min, 75 mmHg), 79% of the pump volume was in the shear stress range of 0-10 Pa with < 1% of the volume in the critical range of 150-1000 Pa for blood damage. At higher speed and flow (5000 RPM, 3.50 L/min, 176 mmHg), 65% of the volume resided in the 0-10 Pa range compared to 2.3% at 150-1000 Pa. The initial computational characterization of the Inspired Pediatric VAD V3 is encouraging and future work will include device prototype testing in a mock circulatory loop and acute large animal model.

Low Thermal Conductivity Adhesive as a Key Enabler for Compact, Low-Cost Packaging for Metal-Oxide Gas Sensors

Metal-oxide (MOX) gas sensors commonly rely on custom packaging solution. With an ever-increasing demand for MOX gas sensors, there is a clear need for a low cost, compact and high-performance package. During normal operation, MOX sensors are heated up to a temperature in the typical range of 200-300°C. However, the generated heat must not damage or degrade any other part of the assembly. Using 3D finite elements modelling, we developed an optimal package configuration. To thermally insulate the assembly from the heated MOX sensor we have developed in-house a low thermal conductivity xerogel-epoxy composite with 22.7% by weight xerogel and a thermal conductivity of 107.9 mW m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> which is a reduction exceeding 30% compared to commercially available epoxy. Based on the low thermal conductivity xerogel-epoxy composite, we have developed a novel packaging approach that can suit the large family of MOX sensors. The developed alternative packaging solution includes a small number of assembly steps and uses standard processes and techniques. The assembled MOX sensor is low cost and has a low power consumption, while all thermally sensitive assembly parts remain at low temperature during the system’s lifetime.

An Optical Interferometry Based MEMS Accelerometer Applicable to Seismic-Grade Measurement

Traditional seismometers and gravimeters normally have large volumes and entail high manufacturing costs. Aiming at the miniaturization of such geophysical instruments, a portable Micro-electro-mechanical Systems (MEMS) accelerometer applicable to seismic-grade measurements is fabricated and characterized in this work. This accelerometer is operating on the deformable grating-based MEMS interferometer, where a new MEMS out-of-plane sensing chip employing double layers of 10 &#x03BC;m-thickness spring is first proposed. The simulation results show that this geometry has a low natural frequency of 52.23 Hz and undergoes a low stress of 26.94 Mpa under the gravitational acceleration. The test of the fabricated prototype is implemented in a quiet environment for tracking the inherent micro seismic peaks of Earth. The evaluation results demonstrate that the fabricated prototype has achieved a voltage sensitivity of 510.6 V/g. Furthermore, the noise estimation indicates that the self-noise of this sensor has reached 20 ng/&#x221A;<i>Hz</i> from 0.3 Hz to 20 Hz, and a bias stability of 235.4 ng is obtainable at room temperature. Combined with the compact package size of 40.5 cm³, the proposed device exhibits a promising prospect in the seismic-grade applications.