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All DC offshore wind farms are gaining popularity for long-distance and high-power offshore wind energy conversion. It calls for high-power DC/DC converter with high step-up ratio for interconnecting the medium-voltage DC collection and the high-voltage DC transmission systems. This paper proposes a monopolar symmetrical DC/DC converter, which is featured with partial-power processing and presents less installed capacity of components, low cost, low power loss, lightweight, and small footprint. Moreover, a modified phase-shifted carrier pulse-width modulation with variable carrier frequency is developed to further reduce the switching loss and keep the dynamic current tracking performance. Effectiveness of the proposed converter has been verified by simulation study of a 400MW, 25kV/250kV model and experimental results of a 5.4kW, 60V/320V scaled-down prototype.

Membranes are widely used in separation processes due to their low energy requirement, small footprint and simplicity. New membranes have been developed based on novel materials and fabrication techniques to address separation challenges in the field of membrane science. In the case of liquid phase separations, ion-ion separation and chiral resolution using membranes have attracted growing interest for their applications such as in high-value mineral extraction and pharmaceutical manufacturing. Furthermore, reverse osmosis operation favors ultra-high-pressure range for treating feed with higher salinity with higher water recovery. Herein we highlight the latest development and design approaches of single species-selective membranes and pressure-resistant membranes and discuss the current limitations of membrane separation in the liquid phase. We subsequently review recent advancement in the fabrication techniques that enable the making of these membranes from emerging materials.

Optomechanical sensing based on the coupling between mechanical motions and optical resonances has attracted huge interest in sensor applications due to its small footprint, high sensitivity, low detection limit, and electromagnetic immunity. Optomechanical sensors that detect from mechanical motion at µm scale to molecular vibration at nm scale have found various applications such as force, inertia, acoustic, chemical, and thermal sensing, etc. In this review, we provide an overview of the recent progress of optomechanical sensors. Three development fields of optomechanical sensors are reviewed, which are passive optomechanical sensors, electro-optomechanical sensing platforms, and molecular vibration sensing schemes. The sensor configurations, applications, and integrations are described. In the end, we also provide our perspectives on the future development directions of optomechanical sensors.

The timely diagnosis of active tuberculosis disease (TB) is crucial to interrupt the transmission and combat the spread of Mycobacterium tuberculosis (Mtb), the causative agent for TB. Here, we demonstrate the development of a specimen-direct rapid diagnostic method for TB which consists of an isothermal amplification device, Tiny Isothermal Nucleic acid quantification sYstem (TINY), coupled with helicase-dependent amplification (HDA). HDA, an isothermal amplification technique is established over TINY using pUCIDT-AMP vector carrying IS6110, the target DNA sequence for Mtb. The limit of detection of this technique for detecting the IS6110 within a threshold time of 50 min is 2.5 × 105 copies of IS6110. HDA in TINY for TB detection was evaluated using three IS6110-positive Mtb strains - H37Rv, CDC 1551, and Erdman wild-type and one IS6110-negative Mycobacterium avium. For spiked oral swabs, HDA in TINY detects IS6110 without any non-specificity in relatively short turnaround time (

Dye-sensitized solar cells (DSCs) have proven to be one of the best photovoltaic approaches for harnessing indoor/artificial light. Herein, we report two new molecularly engineered, cost-effective, metal-free, carbazole-based D–π–A sensitizers (YK 8 and YK 9) by judiciously varying their π-spacers, which are suitable for indoor photovoltaic applications. Using YK 8, we achieved an efficiency of 28.7% under standard 1000 lux Osram 14 W T2 cool day light fluorescent tube illumination with a power output of 68.88 μW cm−2 and 30.24% with a power output of 108.85 μW cm−2 under a higher illumination intensity of 1500 lux without co-sensitizers using iodide/triiodide electrolyte. With a small footprint/active area of 1.24 cm2, we could power a temperature sensor completely autonomously at a low light intensity of 500 lux, displaying the potential of these indoor photovoltaic devices to serve as energy sources for low-power sensors and actuators on the Internet of Things (IoT) network, reducing the dependence on batteries and leading to a smaller carbon footprint. The role of the π-spacer and its influence on recombination and device performance were explored via extensive interfacial studies.

The explosive rise of silicon photonics has led to renewed interest in the electro-optic (EO) or Pockels effect due to its potential uses in many next generation device applications. To find materials with a strong EO response in thin film form, which are essential for low power and small footprint devices, one needs to find a general design rule for strong Pockels materials. To elucidate what makes the Pockels effect strong, we study the effect in LiB3O5 (LBO) and CsB3O5 (CBO) and use these materials as prototypical examples of where conventional wisdom breaks down. We find the Pockels tensor components to be extremely small in both materials, despite the large degree of anharmonicity in the crystals, which has been used as a proxy for the presence of nonlinear electronic effects. We relate the lack of EO response to the large optical phonon frequencies (despite the relatively large Raman susceptibility) in LBO and to the small Raman susceptibility (despite the low phonon frequencies) in CBO, respectively. We shed light on the underlying physical phenomena behind the Raman susceptibility, which we find to be intimately linked to the electron–phonon coupling strength of the near-edge electronic states, and identify a route to discovering new strong EO materials.

Natural hydrocarbon seeps are ubiquitous along continental margins. Despite their significance, we lack a basic understanding of the long-term temporal variability of seep dynamics, including bubble size, rise velocity, composition, and upwelling and entrainment processes. The shortcoming makes it difficult to constrain the global estimates of oil and gas entering the marine environment. Here we report on a multi-method approach based on optical, acoustic, satellite remote sensing, and simulations, to connect the characteristics of a hydrocarbon seep in the Gulf of Mexico to its footprint on the sea surface. Using an in-situ camera, bubble dynamics at the source were measured every 6 h over 153 days and the integrated total hydrocarbon release volume was estimated as 53 m3. The vertical velocity was acoustically measured at 20 m above bed (mab) and found to be approximately 40% less than the dispersed-phase at the source, indicating that the measured values are reflecting the plume continuous-phase flow. Numerical simulations predict that the oily bubbles with diameters larger than 8 mm reach the surface with a small footprint, i.e. forming an oil slick origin, deflection of which with wind and surface current leads to the formation of an oil slick on the surface. Nineteen SAR images are used to estimate the oil seepage rate from GC600 for 2017 giving an average discharge of 14.4 cm3/s.

Optical micro-ring resonator (MRR) sensors are an emerging technology that attracts attention not only because it’s small footprint but also because of its high-quality features. In this work, a Silicon on Insulator (SOI)-based MRR sensor is studied for a practical label-free sensor. After the analysis of this study, it is found that a smaller (compare to previous studies) label-free optical sensor with a sensitivity of 206nm/RIU and a q-factor of 17900 can be obtained when the optimal designed parameters are used. Thus, it is believed that, this work would shed a light on optical sensor technology for more compact-efficient, low-cost and complementary metal-oxide-semiconductor (CMOS)-compatible sensors for daily life usage.

In recent years, the number of permanent residents in Chengdu, Sichuan Province, China has continued to grow, and the number of private cars keeps rising. A series of problems caused by difficult parking and random parking in old communities are common. This paper will take the parking problem of the old community in Yingmenkou community, Chengdu, China as an example to summarize the current situation and parking problems of the private car parking facilities in these old communities. Based on Chengdu’s current old community parking management policy, parking facility renovation and expansion policy, this paper researches and establishes a parking resource sharing model suitable for old communities. The simulation results show that this model has a small footprint and is easy to install and disassemble. It can be freely spliced and combined units according to the size of the old community and the needs of residents. It is suitable for old communities with no centralized parking lot and high parking demand by residents.

Keyword Spotting (KWS) remains challenging to achieve the trade-off between small footprint and high accuracy. Recently proposed metric learning approaches improved the generalizability of models for the KWS task, and 1D-CNN based KWS models have achieved the state-of-the-arts (SOTA) in terms of model size. However, for metric learning, due to data limitations, the speech anchor is highly susceptible to the acoustic environment and speakers. Also, we note that the 1D-CNN models have limited capability to capture long-term temporal acoustic features. To address the above problems, we propose to utilize text anchors to improve the stability of anchors. Furthermore, a new type of model (LG-Net) is exquisitely designed to promote long-short term acoustic feature modeling based on 1D-CNN and self-attention. Experiments are conducted on Google Speech Commands Dataset version 1 (GSCDv1) and 2 (GSCDv2). The results demonstrate that the proposed text anchor based metric learning method shows consistent improvements over speech anchor on representative CNN-based models. Moreover, our LG-Net model achieves SOTA accuracy of 97.67% and 96.79% on two datasets, respectively. It is encouraged to see that our lighter LG-Net with only 74k parameters obtains 96.82% KWS accuracy on the GSCDv1 and 95.77% KWS accuracy on the GSCDv2., Accepted for Interspeech2021

Knowledge of the isocitrate dehydrogenase (IDH) mutation status of glioma patients could provide insights for decision-making during brain surgery. However, pathology is not able to provide such information intraoperatively. Here we describe the first application of a miniature mass spectrometer (MS) to the determination of IDH mutation status in gliomas intraoperatively. The instrumentation was modified to be compatible with use in the operating room. Tandem MS was performed on the oncometabolite, 2-hydroxyglutarate, and a reference metabolite, glutamate, which is not involved in the IDH mutation. Ratios of fragment ion intensities were measured to calculate an IDH mutation score, which was used to differentiate IDH mutant and wild-type tissues. The results of analyzing 25 biopsies from 13 patients indicate that reliable determination of IDH mutation status was achieved (p = 0.0001, using the Kruskal-Wallis non-parametric test). With its small footprint and low power consumption and noise level, this application of miniature mass spectrometers represents a simple and cost-effective platform for an important intraoperative measurement. Graphical abstract.

Radiosynthesis of [1-11C]acetate is well described in literature, but all syntheses either require adaptations in complex commercial synthesizers or rely on closed-source hardware and software control. Arduino microcontrollers are ideal for the compact, flexible, and inexpensive control of low-complexity hardware, making them particularly suited for radiochemistry where operation in space-limited shielded hot cells is mandatory. We established a [1-11C]acetate radiosynthesis module for combination with a [11C]MeI module available in almost every lab working with 11C. Its small footprint even enables back-to-back production in a hot cell already occupied by other modules. Using this setup, we achieved a reliable and flexible supply of this tracer, with radiochemical yields of 51.4 ± 28.2% and radiochemical purities (RCPs) of 94.4 ± 6.7% ( n = 9) in a synthesis time of 15 minutes. Positron emission tomography (PET) and biodistribution analysis demonstrated low background uptake in healthy mice, with highest uptake in liver and kidneys. Arduino microcontrollers have become valuable and versatile tools in our lab for the automatization of low-complexity procedures not requiring full-blown commercial radiochemistry synthesizers, as showcased here for the production of [1-11C]acetate.

This study presents a novel miniaturised ultra-wideband (UWB) multilayer balun embedded into organic packaging substrate of liquid crystal polymer. The broadside coupled stripline structure is adopted in this work to realise UWB performance and TEM mode. The fabricated prototype is self-packaged for electromagnetic shielding, and lightweight, with a small footprint. The proposed balun design achieves excellent amplitude and phase balances within the entire bandwidth, centred at 6.2 GHz. Simulation and measurement results show very good agreement.

Long short-term memory RNNs (LSTMRNNs) have shown great success in the Automatic speech recognition (ASR) field and have become the state-ofthe- art acoustic model for time-sequence modeling tasks. However, it is still difficult to train deep LSTM-RNNs while keeping the parameter number small. We use the highway connections between memory cells in adjacent layers to train a small-footprint highway LSTM-RNNs (HLSTM-RNNs), which are deeper and thinner compared to conventional LSTM-RNNs. The experiments on the Switchboard (SWBD) indicate that we can train thinner and deeper HLSTM-RNNs with a smaller parameter number than the conventional 3-layer LSTM-RNNs and a lower Word error rate (WER) than the conventional one. Compared with the counterparts of small-footprint LSTMRNNs, the small-footprint HLSTM-RNNs show greater reduction in WER.

We experimentally demonstrate a spectrometer, which consists of an arrayed waveguide grating (AWG), tunable microring resonator (MRR) array, and waveguide-coupled Ge-on-Si photodetector, all integrated onto a single chip. The spectrometer achieves high resolution (0.1 ± 0.029 nm) and large bandwidth (25.4 nm) in 9 channels with a small footprint of 3 × 3 mm2. It has high potential to enable a high-performance spectrometer for applications such as environmental monitoring, spectroscopy, biological and chemical sensing, etc. Ministry of Education (MOE) National Research Foundation (NRF) Published version This work was supported in part by Ministry of Education, Singapore under Tier 3 (MOE2017-T3-1-001) and Tier 1 (RG182/16 (S)) and in part by the Singapore National Research Foundation under the Competitive Research Program (NRF-CRP13-2014-01) and the Incentive for Research & Innovation Scheme (1102-IRIS-05- 05) administered by EWI.

Traditional Potentiometric Ion-selective Electrodes (ISE) are widely used in industrial and clinical settings. The simplicity and small footprint of ISE have encouraged their recent adoption as wearable/implantable sensors for personalized healthcare and precision agriculture, creating a new set of unique challenges absent in traditional ISE. In this paper, we develop a fundamental physics-based model to describe both steady-state and transient responses of ISE relevant for wearable/implantable sensors. The model is encapsulated in a "generalized Nernst formula" that explicitly accounts for the analyte density, time-dynamics of signal transduction, ion-selective membrane thickness, and other sensor parameters. The formula is validated numerically by self-consistent modeling of multispecies ion-transport and experimentally by interpreting the time dynamics and thickness dependence of thin-film solid-contact and graphene-based ISE sensors for measuring soil nitrate concentration. These fundamental results will support the accelerated development of ISE for wearable/implantable applications.

A miniaturized reliability test system for microdevices with controlled environmental parameters is presented. The system is capable of measuring key electrical parameters of the microdevices while controlling the environmental conditions around the microdevices. The test system is compact and thus can be integrated with standard test equipment for microdevices. By using a feed-forward decoupling algorithm, the presented test system is capable of generating a temperature range of 0–120 °C and a humidity range of 20–90% RH (0–55 °C), within a small footprint and weight. The accuracy for temperature and humidity control is ±0.1 °C and ±1% RH (30 °C), respectively. The functionality of the proposed test system is verified by integrating it with a piezo shaker to test the environmental reliability of an electromagnetic vibration energy harvester. The proposed system can be used as a proof-of-technology platform for characterizing the performance of microdevices with controlled environmental parameters.

Wireless battery free and fully implantable tools for the interrogation of the central and peripheral nervous system have quantitatively expanded the capabilities to study mechanistic and circuit level behavior in freely moving rodents. The light weight and small footprint of such devices enables full subdermal implantation that results in the capability to perform studies with minimal impact on subject behavior and yields broad application in a range of experimental paradigms. While these advantages have been successfully proven in rodents that move predominantly in 2D, the full potential of a wireless and battery free device can be harnessed with flying species, where interrogation with tethered devices is very difficult or impossible. Here we report on a wireless, battery free and multimodal platform that enables optogenetic stimulation and physiological temperature recording in a highly miniaturized form factor for use in songbirds. The systems are enabled by behavior guided primary antenna design and advanced energy management to ensure stable optogenetic stimulation and thermography throughout 3D experimental arenas. Collectively, these design approaches quantitatively expand the use of wireless subdermally implantable neuromodulation and sensing tools to species previously excluded from in vivo real time experiments., Studies requiring neural modulation in species that fly are difficult because of the need for wired connections to record experimental data. Here, Ausra et al. present a wireless and battery free device that achieves this in songbirds, model organisms used to study vocal learning and maintenance.

Background Intraoperative frozen section (FS) consultation is an important tool in surgical oncology that suffers from sampling error because the pathologist does not always know where to perform a biopsy of the surgical specimen. Intraoperative molecular imaging is a technology used in the OR to visualize lesions during surgery. We hypothesized that molecular imaging can address this pathology challenge in FS by visualizing the cancer cells in the specimen in the pathology suite. Here, we report the development and validation of a molecular-imaging capable cryostat called Smart-Cut. Methods A molecular imaging capable cryostat prototype was developed and tested using a murine model. Tumors grown in mice were targeted with a NIR contrast agent, indocyanine green (ICG), via tail vein injection. Tumors and adjacent normal tissue samples were frozen sectioned with Smart-Cut. Fluorescent sections and non-fluorescent sections were prepared for H&E and fluorescent microscopy. Fluorescent signal was quantified by tumor-to-background ratio (TBR). NIR fluorescence was tested in one patient enrolled in a clinical trial. Results The Smart-Cut prototype has a small footprint and fits well in the pathology suite. Fluorescence imaging with Smart-Cut identified cancerous tissue in the specimen in all 12 mice. No false positives or false negatives were seen, as confirmed by H&E. The mean TBR in Smart-Cut positive tissue sections was 6.8 (SD±3.8). In a clinical application in the pathology suite, NIR imaging identified two lesions in a pulmonary resection specimen, where traditional grossing only identified one. Conclusion Molecular imaging can be integrated into the pathology suite via the Smart-Cut device, and can detect cancer in frozen tissue sections using molecular imaging in a murine model.

Fluids are a vital tool in the armament of acute care clinicians in both civilian and military resuscitation. We now better understand complications from inappropriate resuscitation with currently available fluids; however, fluid resuscitation undeniably remains a life-saving intervention. Military research has driven the most significant advances in the field of fluid resuscitation and is currently leading the search for the fluids of the future. The veterinary community, much like our civilian human counterparts, should expect the fluid of the future to be the fruit of military research. The fluids of the future not only are expected to improve patient outcomes but also be field expedient. Those fluids should be compatible with military environments or natural disaster environments. For decades, military personnel and disaster responders have faced the peculiar demands of austere environments, prolonged field care, and delayed evacuation. Large scale natural disasters present field limitations often similar to those encountered in the battlefield. The fluids of the future should, therefore, have a long shelf-life, a small footprint, and be resistant to large temperature swings, for instance. Traumatic brain injury and hemorrhagic shock are the leading causes of preventable death for military casualties and a significant burden in civilian populations. The military and civilian health systems are focusing efforts on field-expedient fluids that will be specifically relevant for the management of those conditions. Fluids are expected to be compatible with blood products, increase oxygen-carrying capabilities, promote hemostasis, and be easy to administer in the prehospital setting, to match the broad spectrum of current acute care challenges, such as sepsis and severe systemic inflammation. This article will review historical military and civilian contributions to current resuscitation strategies, describe the expectations for the fluids of the future, and describe select ongoing research efforts with a review of current animal data.

Small footprint embedded devices require keyword spotters (KWS) with small model size and detection latency for enabling voice assistants. Such a keyword is often referred to as \textit{wake word} as it is used to wake up voice assistant enabled devices. Together with wake word detection, accurate estimation of wake word endpoints (start and end) is an important task of KWS. In this paper, we propose two new methods for detecting the endpoints of wake words in neural KWS that use single-stage word-level neural networks. Our results show that the new techniques give superior accuracy for detecting wake words' endpoints of up to 50 msec standard error versus human annotations, on par with the conventional Acoustic Model plus HMM forced alignment. To our knowledge, this is the first study of wake word endpoints detection methods for single-stage neural KWS., Comment: Proceedings of INTERSPEECH

Advancements in medical microrobotics have given rise to an abundance of agents capable of localised interaction with human body in small scales. Nevertheless, clinically-relevant applications of this technology are still limited by the auxiliary infrastructure required for actuation of micro-agents. In this letter, we approach this challenge. Using finite-element analysis, we show that miniaturization of electromagnets can be used to create systems capable of providing magnetic forces adequate for micro-agent steering, while retaining small footprint and power consumption. We use these observations to create MILiMAC (Microrobotic Infrastructure Loaded into Magnetically-Actuated Catheter). MILiMAC is a flexible catheter employing three miniaturized electromagnets to provide localized magnetic actuation at the deeply-seated microsurgery site. We test our approach in a proof-of-concept study deploying MILiMAC inside a test platform to deliver and steer a 600 [\boldsymbol{\mu }m] ferromagnetic microbead. The bead is steered along a set of user-defined trajectories using closed-loop position control. Across all trajectories the best performance metrics are the mean error of 0.41 [mm] and the steady-state error of 0.27 [mm].

Background Medical schools worldwide allocate little time and utilize varying formats in the teaching of occupational medicine (OM) to undergraduate medical students. Aims To identify undergraduate OM teaching formats and highlight key findings in these different methods. Methods A limited literature search conducted on PubMed and Scopus identified relevant articles published in English and between the years 2009 and 2018. Our inclusion criteria were papers containing the key words (‘occupational medicine’ AND (‘medical students’ OR ‘undergraduate medical’)) OR (‘occupational medicine’ AND (‘training’ OR ‘education’ OR ‘teaching’)) in the title or abstract and those that specifically discussed OM education. Results The literature search yielded 1479 papers. Seven of them fulfilled the inclusion criteria and were reviewed in full. Formats in OM education of undergraduate medical students include, either singly or in combination, the use of case studies, didactic sessions, workplace visits, text-based readings and pro forma. Conclusions OM education has a very small footprint in most undergraduate medical curricula. The studies show that different teaching formats are utilized, often in combination. Case-based discussions and workplace visits are frequently used with good qualitative results. Text-based readings will serve well to build good foundational knowledge, though there is no conclusive evidence that students will perform better.

Background Applying ultrasonic imaging system during surgery requires the poring of saline, performing the measurement, and acquiring data from its display—which requires time and is highly “performer dependent,” i.e., the measure is of a subjective nature. A new ultrasonic device was recently developed that overcomes most of these drawbacks and was successfully applied during tumor-in-brain neurosurgeries. The purpose of this study was to compare the two types of US devices and demonstrate their properties. Methods The study was performed in the following stages: (i) an ex vivo experiment, where slices of the muscle and brain of a young porcine were laid one on top the other. Thicknesses and border depths were measured and compared, using the two types of US instruments. (ii) During human clinical neurosurgeries, tumor depth was compared by measuring it with both devices. (iii) Following the success of stages (i) and (ii), using solely the new US device, the tumor thickness was monitored while its resection. Correlation, Pearson’s coefficient, average, mean, and standard deviation were applied for statistical tests. Results A high correlation was obtained for the distances of tissue borders and for their respective thicknesses. Applying these ultrasonic devices during neurosurgeries, tumor depths were monitored with high similarity (87%), which was also obtained by Pearson’s correlation coefficient (0.44). The new US device, thanks to its small footprint, its remote measurement, and the capability of monitoring intraoperatively and in real-time, provides the approach to tumor’s border before its complete resection. Conclusions The new US device provides better accuracy than an ultrasonic imaging system; its data is objective; it enables to control the residual tumor thickness during its resection, and it is especially useful in restricted areas. These features were found of great help during a tumor-in-brain surgery and especially in the final stages of tumor’s resection.

This paper proposes an electrothermally-actuated circular pyramidal kirigami microscanner with a millimeter-range low-power lens drive for endoscopic biomedical applications. A variation of Japanese origami art, kirigami involves creation of out-of-plane structures by paper cutting and folding. The proposed microscanner is composed of freestanding kirigami film on which the spiral-curved thermal bimorphs are strategically placed. The kirigami microscanner is electrothermally transformed into an out-of-plane circular multistep pyramid by Joule heating. The circular pyramidal kirigami microscanner on a small footprint of 4.5 mm × 4.5 mm was fabricated by microelectromechanical system processes. A large four-step pyramidal actuation was successfully demonstrated, and a large 1.1-mm lens travel range at only 128 mW was achieved.

Multi-attribute methods (MAM), based on proteolytic digestion followed by liquid chromatography-mass spectrometry analysis of proteolytic peptides, have gained substantial attention in the biopharmaceutical industry for quantifying a variety of quality attributes for therapeutic proteins. Most MAM developed so far have been based on high-resolution mass spectrometers, due to their superb resolving power to distinguish analyte signals from interferences. Lower-resolution instruments, if demonstrated suitable, may further promote the adoption of the technology due to their low cost, small footprint, and ease of use. In this work, we compared the performance of a high-resolution instrument with a few low-resolution quadrupole-type instruments in quantifying a diverse set of quality attributes in a monoclonal antibody product. Different modes of operation for the quadrupole instruments, including scan mode, selected-ion monitoring and multiple-reaction monitoring, were evaluated. The high-resolution instrument has superb performance, with a quantitation limit of 0.002%. Single-quadrupole instruments in scan mode, on the other hand, provide a quantitation limit of about 1%, which may be fit-for-purpose for many routine MAM applications.

The development of autonomous and stand-alone electronics with a small footprint size has prompted an increasing demand for high-performance energy-storage devices, with rechargeable three-dimensional (3D) batteries being one of these ideal energy devices. As batteries made up of 3D configurations become increasingly important in our daily lives, it is of similar importance to model their behaviors. Besides experimental studies, simulation modeling and analysis is another important approach to optimize the battery design and understand the electrochemical uniqueness of 3D batteries, such as construction principle, current and voltage distribution, and structure stability and evolution. In this work, we discuss the progress of theoretical research in 3D batteries and offer some general insights into their further development. It is hoped that this work will stimulate more exciting investigations, thus contributing to their mass deployment in electronics.

For about 30 years, MRI set cruising speed at 1.5 T of magnetic field, with a gentle transition towards 3 T systems. In its first 10 years of existence, there was an open debate on the question of most relevant MRI field strengths considering the gain in T1 contrast, simpler cooling strategies, lower predisposition to generating image artifacts, and naturally cost reduction of small footprint low field systems. At the time, the inherent gain in sensitivity of high field, which would translate in more signal per unit time, quickly ended this debate. The promise of rapid exams or higher image resolution within a reasonable time won over other considerations and set the standards for MR value. Yet, many reasons bring low field MRI in a situation quite different from 40 years ago. From the achieved progress regarding all aspects of MRI technology, an MR scan at 1.5 T in the mid 1980s has very little in common with the equivalent scan in 2020. That clearly indicates that field strength alone is not what drives performance. It is also unlikely that the total number of machines worldwide will grow so to follow the increasing demand considering their overall cost ($1M/T). The natural trend is to better control medical expenses worldwide, and reconsidering low-field MRI could lead to the democratization of dedicated, point-of-care devices to decongest high-field clinical scanners. In the present article, we aim to draw an extensive portrait of most recent MRI developments at low (1-199 mT) and ultra-low field (micro-Tesla range) outside of the commercial sphere, and we propose to discuss their potential relevance in future clinical applications. We will cover a broad spectrum from pre-polarized MRI using ultra-sensitive magnetic sensors up to permanent and resistive magnets in compact designs.

Implantable technologies are becoming more widespread for biomedical applications that include physical identification, health diagnosis, monitoring, recording, and treatment of human physiological traits. However, energy harvesting and power generation beneath the human tissue are still a major challenge. In this regard, self-powered implantable devices that scavenge energy from the human body are attractive for long-term monitoring of human physiological traits. Thanks to advancements in material science and nanotechnology, energy harvesting techniques that rely on piezoelectricity, thermoelectricity, biofuel, and radio frequency power transfer are emerging. However, all these techniques suffer from limitations that include low power output, bulky size, or low efficiency. Photovoltaic (PV) energy conversion is one of the most promising candidates for implantable applications due to their higher-power conversion efficiencies and small footprint. Herein, the latest implantable energy harvesting technologies are surveyed. A comparison between the different state-of-the-art power harvesting methods is also provided. Finally, recommendations are provided regarding the feasibility of PV cells as an in vivo energy harvester, with an emphasis on skin penetration, fabrication, encapsulation, durability, biocompatibility, and power management.

A Piano Key weir (PK weir) is a nonlinear, labyrinth-type weir well suited for rehabilitation projects due to a relatively small footprint and the ability to pass large discharges for lesser upstream-head values when compared with other weir types. A critical component of a hydraulic structure is the energy-dissipative properties. Currently, information and guidance is limited, with previous energy dissipation studies of PK weirs primarily of specific projects. Therefore, to document and quantify energy dissipation, four laboratory-scale Type A PK weir models with different width ratios (Wi/Wo) were studied, with 255 tests comprising this new dataset, along with detailed observations of the flow field. Results were compared to existing published data regarding energy dissipation downstream of trapezoidal and rectangular labyrinth weirs. To support design efforts, two equations, both functions of head-water ratio (H/P) and Wi/Wo, are proposed to predict the relative residual energy downstream of PK weirs. The energy dissipation of PK weirs is largest at low flows and decreases in a logarithmic-like manner as flow increases. PK weirs with increased hydraulic efficiency, caused by an increase in Wi/Wo, resulted in slightly smaller energy dissipation values within the range 0.2 &le, H/P &le, 0.8. The energy dissipation of PK weirs was found to be relatively constant, independent of Wi/Wo, and in the ranges 0.07 &le, 0.2 and 0.8 &le, 0.95.

Simultaneous on‐chip sensing of multiple greenhouse gases in a complex gas environment is highly desirable in industry, agriculture, and meteorology, but remains challenging due to their ultralow concentrations and mutual interference. Porous microstructure and extremely high surface areas in metal–organic frameworks (MOFs) provide both excellent adsorption selectivity and high gases affinity for multigas sensing. Herein, it is described that integrating MOFs into a multiresonant surface‐enhanced infrared absorption (SEIRA) platform can overcome the shortcomings of poor selectivity in multigas sensing and enable simultaneous on‐chip sensing of greenhouse gases with ultralow concentrations. The strategy leverages the near‐field intensity enhancement (over 1500‐fold) of multiresonant SEIRA technique and the outstanding gas selectivity and affinity of MOFs. It is experimentally demonstrated that the MOF–SEIRA platform achieves simultaneous on‐chip sensing of CO2 and CH4 with fast response time (, Porous metal–organic frameworks are provided with excellent gas adsorption selectivity due to their extremely high surface areas. Integrating it into the multiresonant surface‐enhanced infrared absorption platform overcomes the shortcomings of poor selectivity in gas sensing and enables simultaneous on‐chip sensing of greenhouse gases. Importantly, the strategy shows a competitive advantage in terms of response time, accuracy, footprint, and linearity.

The Internet of Things (IoT) has begun to acquire place in our lives quietly and gradually thanks to the presence of wireless communication systems. An increasing number of M2M applications, such as smart meters, healthcare monitoring, transportation and packaging, or asset tracking, make a significant contribution to the growth of devices and connections. Within such a large and uncontrollable ecosystem, IoT poses several new problems. Security and privacy are among the most important of these problems. Lightweight cryptography can be used more effectively for small size, low energy, and small footprint such as RFID tags, sensors, and contactless smart cards. Therefore, it can be used to ensure security and privacy in the IoT applications. In this study, PRESENT, CLEFIA, PICCOLO, PRINCE, and LBLOCK lightweight cryptographic algorithms, which can be used to secure data in IoT applications, were analyzed in a test environment. As a result of the tests, the energy consumption of the algorithms, current measurement, active mode working time, and active mode energy consumption were identified and based on this, some inferences have been made.

We present a novel microfluidic system that produces the required concentration of a reagent in a single droplet or that produces a sequence of droplets with a defined periodic distribution of concentrations. We use digital algorithms that, through a series of simple operations, such as merging and splitting droplets, ensure superior precision, repeatability and flexibility in concentration setting. Unlike Digital microfluidic (DMF) systems based on electrowetting on dielectric (EWOD) commonly used to implement digital algorithms in the droplet world, our approach is based on much more available channel-based microfluidics operated by programmable syringe pumps. Furthermore, the small footprint of our system makes it easy to integrate with other structures of microfluidic networks. Thus, this technique is a comprehensive component that can be built into the microfluidic networks executing laboratory analytical tasks in chemistry or biology to enrich their performance and offer new functionalities.

For a cardiologist, lung ultrasound is an add-on to transthoracic echocardiography, just as lung auscultation is part of a cardiac physical examination. A cardiac 3.5- to 5.0-MHz transducer is generally suitable because the small footprint makes it ideal for scanning intercostal spaces. The image quality is often adequate, and the lung acoustic window is always patent. The cumulative increase in imaging time is 1 min for the 2 main applications targeted on pleural water (pleural effusion) and lung water (pulmonary congestion as multiple B-lines). In these settings, lung ultrasound outperforms the diagnostic accuracy of the chest radiograph, with a low-cost, portable, real-time, radiation-free method. A "wet lung" detected by lung ultrasound predicts impending acute heart failure decompensation and may trigger lung decongestion therapy. The doctors of tomorrow may still listen with a stethoscope to their patient's lung, but they will certainly be seeing it with ultrasound.

In orthopedic hand surgeries C-arms are the standard imaging modalities for procedure and tool guidance. However, the currently used systems have a large footprint and high weight, which can lead to workspace restrictions and difficult positioning of the device at the desired imaging position. The aim of this paper is to present a prototype of a new, flexible, lightweight and small footprint X-ray system, which is capable to create 2D projection images from different orientations. The new design includes a miniaturized Xray tube covered in a custom-made case mounted on a flexible holding arm attached to the standard OR table rail. With that, fast positioning and fixation for the subsequent image acquisition is achieved. A flat panel detector is placed in an adjustable metal sheet construction below the table. For safety aspects an overlay of the X-ray cone beam with an integrated light source visualizes the irradiation area. The acquired images are visualized on a 2-in-1 netbook. A foot pedal initiates the imaging process. A prototype of the free movable miniaturized X-ray system FlexScan was build. Workspace restriction, usability and general imaging needs were simulated and tested. FlexScan has the potential to improve X-ray guided interventions on extremities especially for small private surgery centers. It fulfills the general imaging needs and is capable of producing 2D projection images from different orientations within a small and lightweight setup.

The whole world is looking for imperative technologies that can produce clean water, clean energy and clean environments with low energy consumption and small footprint. Membrane technology stands out as a potential solution for different applications because of its beneficial advantages. The revolutionary dual-layer (DL) membranes are composed of two layers formed by co-extruding or co-casting two different dope solutions simultaneously in one step. With the advances in dual-layer concept, one can effectively design the membranes with the maximal performance from various polymeric pairs. As a result, DL membranes are increasingly being studied for gas-phase and liquid-phase separations. However, challenges still exist such as parameters or conditions affecting the adhesion/delamination in DL membranes, the methods to fabricate delamination-free membranes, the knowledge to bridge the fabrication conditions and their influence on membrane performance. Therefore, this review not only summarizes the state-of-the-art research on DL membranes but also provides critical insights on these scientific challenges and potential solutions. A future perspective on this technology including other challenges is also given.

Isothermal nucleic acid amplification methods can potentially shorten the amount of time required to diagnose influenza. We developed and evaluated a novel isothermal nucleic acid amplification method, RT-SIBA to rapidly detect and differentiate between influenza A and B viruses in a single reaction tube. The performance of the RT-SIBA Influenza assay was compared with two established RT-PCR methods. The sensitivities of the RT-SIBA, RealStar RT-PCR, and CDC RT-PCR assays for the detection of influenza A and B viruses in the clinical specimens were 98.8%, 100%, and 89.3%, respectively. All three assays demonstrated a specificity of 100%. The average time to positive result was significantly shorter with the RT-SIBA Influenza assay (90 min). The method can be run using battery-operated, portable devices with a small footprint and therefore has potential applications in both laboratory and near-patient settings., Highlights • We developed and evaluated novel isothermal nucleic acid amplification method for the rapid detection and differentiation of influenza A and B viruses in human respiratory specimens. • The method displayed high level of sensitivity and specificity and correlated well with those of the reference methods. • The method detected influenza virus within 20 minutes and can potentially be used in near patient or field setting.

The ability to perform laboratory testing near the patient and with smaller blood volumes would benefit patients and physicians alike. We describe our design of a miniaturized clinical laboratory system with three components: a hardware platform (ie, the miniLab) that performs preanalytical and analytical processing steps using miniaturized sample manipulation and detection modules, an assay-configurable cartridge that provides consumable materials and assay reagents, and a server that communicates bidirectionally with the miniLab to manage assay-specific protocols and analyze, store, and report results (i.e., the virtual analyzer). The miniLab can detect analytes in blood using multiple methods, including molecular diagnostics, immunoassays, clinical chemistry, and hematology. Analytical performance results show that our qualitative Zika virus assay has a limit of detection of 55 genomic copies/ml. For our anti-herpes simplex virus type 2 immunoglobulin G, lipid panel, and lymphocyte subset panel assays, the miniLab has low imprecision, and method comparison results agree well with those from the United States Food and Drug Administration-cleared devices. With its small footprint and versatility, the miniLab has the potential to provide testing of a range of analytes in decentralized locations.

Facilitated by microelectromechanical systems (MEMS) technology, MEMS speakers or microspeakers have been rapidly developed during the past decade to meet the requirements of the flourishing audio market. With advantages of a small footprint, low cost, and easy assembly, MEMS speakers are drawing extensive attention for potential applications in hearing instruments, portable electronics, and the Internet of Things (IoT). MEMS speakers based on different transduction mechanisms, including piezoelectric, electrodynamic, electrostatic, and thermoacoustic actuation, have been developed and significant progresses have been made in commercialization in the last few years. In this article, the principle and modeling of each MEMS speaker type is briefly introduced first. Then, the development of MEMS speakers is reviewed with key specifications of state-of-the-art MEMS speakers summarized. The advantages and challenges of all four types of MEMS speakers are compared and discussed. New approaches to improve sound pressure levels (SPLs) of MEMS speakers are also proposed. Finally, the remaining challenges and outlook of MEMS speakers are given.

Purpose: To report a novel, telemedicine-friendly, smartphone-based, wireless anterior segment device with instant photo-documentation ability in the COVID-19 era. Methods: Anterior Imaging Module (AIM) was constructed based on a 50/50 beam splitter design, to match the magnification drum optics of slit-lamps with a three-step or higher level of magnification. The design fills the smartphone sensor fully at the lowest magnification and matches the fixed focus of the slit-lamp. It comes with a smartphone for instant photo-documentation, an in-built software application for data-management and secure HIPAA compliant cloud storage, and a Bluetooth trigger for a one-tap image capture. The construction of the device is explained, and the optical resolution measured using U.S. air-force resolution test. AIM’s performance was characterized with traceability to internationally relevant performance standards for digital slit-lamps after image quality assessment through a pilot study. Results: Clinically useful anterior segment images were obtained with both diffuse and slit illumination at different magnification settings with the highest magnification (40X) resolution of 359 lines per cm and the lowest magnification (16X) resolution of 113 lines per cm. Conclusion: AIM is a novel, wireless, telemedicine-enabled design that digitizes existing, analog slit lamps with at least three-step magnification. The settings ensure the focus is determined purely by the position of the slit-lamp. Hence, the image viewed and captured on the smartphone is exactly what the clinician sees through the eyepiece. This helps in maintaining distance from the patient in the ongoing COVID-19 pandemic, as well.