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Transition metal oxides (TMOs) have been widely studied as potential next-generation anode materials, owing to their high theoretical gravimetric capacity. However, to date, these anodes syntheses are plagued with time-consuming preparation processes, two-dimensional electrode fabrication, binder requirements, and short operational cycling lives. Here, we present a scalable single-step reagentless process for the synthesis of highly dense Mn3O4-based nanonetwork anodes based on a simple thermal treatment transformation of low-grade steel substrates. The monolithic solid-state chemical self-transformation of the steel substrate results in a highly dense forest of Mn3O4nanowires, which transforms the electrochemically inactive steel substrate into an electrochemically highly active anode. The proposed method, beyond greatly improving the current TMO performance, surpasses state-of-the-art commercial silicon anodes in terms of capacity and stability. The three-dimensional self-standing anode exhibits remarkably high capacities (>1500 mA h/g), a stable cycle life (>650 cycles), high Coulombic efficiencies (>99.5%), fast rate performance (>1.5 C), and high areal capacities (>2.5 mA h/cm2). This novel experimental paradigm acts as a milestone for next-generation anode materials in lithium-ion batteries, and pioneers a universal method to transform different kinds of widely available, low-cost, steel substrates into electrochemically active, free-standing anodes and allows for the massive reduction of anode production complexity and costs.

Here, we propose a novel method for the synthesis of extremely uniform, diversely doped silicon nanotube heterostructures. The method, comprising a simple two-step synthesis, exploits the use of a Ge nanowire sacrificial core upon which a multidoping axial pattern can be easily obtained, that is enclosed in an intrinsic Si shell. The Ge–Si core–shell structure is then heated to 750 °C, allowing the migration of dopant elements from the Ge core directly into the Si shell. Removal of the Ge core, via either wet or dry etch, does not impair the crystallinity of the Si shell nor its electrical characteristics, allowing for the formation of a multidoped axially patterned, conformal, and uniform Si nanotube. The precise dopant patterning allows for the extension of Si nanotube applications, which were unattainable because of the inability to precisely control the parameters and uniformity of the nanotubes while doping the structure simultaneously.

An ever-growing demand for uranium in various industries raises concern for human health of both occupationally exposed personnel and the general population. Toxicological effects related to uranium (natural, enriched, or depleted uranium) intake involve renal, pulmonary, neurological, skeletal, and hepatic damage. Absorbed uranium is filtered by the kidneys and excreted in the urine, thus making uranium detection in urine a primary indication for exposure and body burden assessment. Therefore, the detection of uranium contamination in bio-samples (urine, blood, saliva, etc.,) is of crucial importance in the field of occupational exposure and human health-related applications, as well as in nuclear forensics. However, the direct determination of uranium in bio-samples is challenging because of “ultra-low” concentrations of uranium, inherent matrix complexity, and sample diversity, which pose a great analytical challenge to existing detection methods. Here, we report on the direct, real-time, sensitive, and selective detection of uranyl ions in unprocessed and undiluted urine samples using a uranyl-binding aptamer-modified silicon nanowire-based field-effect transistor (SiNW-FET) biosensor, with a detection limit in the picomolar concentration range. The aptamer-modified SiNW-FET presented in this work enables the simple and sensitive detection of uranyl in urine samples. The experimental approach has a straight-forward implementation to other metals and toxic elements, given the availability of target-specific aptamers. Combining the high surface-to-volume ratio of SiNWs, the high affinity and selectivity of the uranyl-binding aptamer, and the distinctive sensing methodology gives rise to a practical platform, offering simple and straightforward sensing of uranyl levels in urine, suitable for field deployment and point-of-care applications.

Here, we report on the simple, catalyst-free preparation and application of carbon nanotube–silicon core–shell composite anodes on stainless steel. The stainless steel mesh structure acts as a self-catalyzing agent for the plasma-enhanced chemical vapor deposition (PECVD) growth of vertically aligned, dense, multiwalled carbon nanotube arrays. The carbon nanotube array then serves as a bed for silicon deposition by the decomposition of silane through chemical vapor deposition (CVD). This approach leads to the formation of highly conductive and stable composite anodes. Silicon deposition on the substrate is controlled in terms of the optimal silicon shell thickness, thus enhancing the performance of the cell. These extremely stable, binder-free composite electrodes were characterized as potential anodes in Li-ion batteries, exhibiting long cycle life (>700 cycles), high gravimetric capacity (>4000 mAh/gSi), low irreversible capacity (<10%), and high Coulombic efficiency (>99.5%). These composite anodes meet the requirements of Li-ion batteries for future portable electronics and electric vehicle applications.

Here, we report on the large-scale one-step preparation, characterization, and application of three-dimensional spongelike silicon alloy composite anodes, based on the catalyst-free growth of porous silicon nanonetworks directly onto highly conductive and flexible open-structure stainless steel current collectors. By the use of a key hydrofluoric-acid-based chemical pretreatment process, the originally noncatalytic stainless steel matrix becomes nanoporous and highly self-catalytic, thus greatly promoting the formation of a silicon spongelike network at unexpectedly low growth temperatures, 380–460 °C. Modulation of this unique chemical pretreatment allows control over the morphology and loading properties of the resulting silicon network. The spongelike silicon network growth is capable of completely filling the openings of the three-dimensional stainless steel substrates, thus allowing full control over the active material loading, while conserving high mechanical and chemical stabilities. Furthermore, extremely high silicon loadings are reached because of the supercatalytic nanoporous nature of the chemically treated stainless steel substrates (0.5–20 mg/cm2). This approach leads to the realization of highly electrically conductive Si–stainless steel composite anodes, due to the formation of silicon-network-to-stainless-steel contact sections composed of highly conductive metal silicide alloys, thus improving the electrical interface and mechanical stability between the silicon active network and the highly conductive metal current collector. More importantly, our one-step cost-effective growth approach allows the large-scale preparation of highly homogeneous ultrathin binder-free anodes, up to 2 m long, using a home-built CVD setup. Finally, we made use of these novel anodes for the assembly of Li-ion batteries exhibiting stable cycle life (cycled for over 500 cycles with <50% capacity loss at 0.1 mA), high gravimetric capacity (>3500 mA h/gSiat 0.1 mA/cm2), low irreversible capacity (<10%), and high Coulombic efficiency (>99.5%). Notably, these Si spongelike composite anodes of novel architecture meet the requirements of lithium batteries for future portable and electric-vehicle applications.

Protein biomarkers’ detection is of utmost importance for preventive medicine and early detection of illnesses. Today, their detection relies entirely on clinical tests consisting of painful, invasive extraction of large volumes of venous blood; time-consuming postextraction sample manipulation procedures; and mostly label-based complex detection approaches. Here, we report on a point-of-care (POC) diagnosis paradigm based on the application of intradermal finger prick-based electronic nanosensors arrays for protein biomarkers’ direct detection and quantification down to the sub-pM range, without the need for blood extraction and sample manipulation steps. The nanobioelectronic array performs biomarker sensing by a rapid intradermal prick-based sampling of proteins biomarkers directly from the capillary blood pool accumulating at the site of the microneedle puncture, requiring only 2 min and less than one microliter of a blood sample for a complete analysis. A 1 mm long microneedle element was optimal in allowing for pain-free dermal sampling with a 100% success rate of reaching and rupturing dermis capillaries. Current common micromachining processes and top-down fabrication techniques allow the nanobioelectronic sensor arrays to provide accurate and reliable clinical diagnostic results using multiple sensing elements in each microneedle and all-in-one direct and label-free multiplex biomarkers detection. Preliminary successful clinical studies performed on human volunteers demonstrated the ability of our intradermal, in-skin, blood extraction-free detection platform to accurately detect protein biomarkers as a plausible POC detection for future replacement of today’s invasive clinical blood tests. This approach can be readily extended in the future to detect other clinically relevant circulating biomarkers, such as miRNAs, free-DNAs, exosomes, and small metabolites.

In order to reduce medical facility overload due to the rise of the elderly population, modern lifestyle diseases, or pandemics, the medical industry is currently developing point-of-care and home medical device systems. Diabetes is an incurable and lifetime disease, accountable for a significant mortality and socio-economic public health burden. Thus, tight glucose control in diabetic patients, which can prevent the onset of its late complications, is of enormous importance. Despite recent advances, the current best achievable management of glucose control is still inadequate, due to several key limitations in the system components, mainly related to the reliability of sensing components, both temporally and chemically, and the integration of sensing and delivery components in a single wearable platform, which is yet to be achieved. Thus, advanced closed-loop artificial pancreas systems able to modulate insulin delivery according to the measured sensor glucose levels, independently of patient supervision, represent a key requirement of development efforts. Here, we demonstrate a minimally invasive, transdermal, multiplex, and versatile continuous metabolites monitoring system in the subcutaneous interstitial fluid space based on a chemically modified SiNW-FET nanosensor array on microneedle elements. Using this technology, ISF-borne metabolites require no extraction and are measured directly and continuously by the nanosensors. Due to their chemical sensing mechanism, the nanosensor response is only influenced by the specific metabolite of interest, and no response is observed in the presence of potential exogenous and endogenous interferents known to seriously affect the response of current electrochemical glucose detection approaches. The 2D architecture of this platform, using a single SOI substrate as a top-down multipurpose material, resulted in a standard fabricated chip with 3D functionality. After proving the ability of the system to act as a selective multimetabolites sensor, we have implemented our platform to reach our main goal for in vivocontinuous glucose monitoring of healthy human subjects. Furthermore, minor adjustments to the fabrication technique allow the on-chip integration of microinjection needle elements, which can ideally be used as a drug delivery system. Preliminary experiments on a mice animal model successfully demonstrated the single-chip capability to both monitor glucose levels as well as deliver insulin. By that, we hope to provide in the future a cost-effective and reliable wearable personalized clinical tool for patients and a strong tool for research, which will be able to perform direct monitoring of clinical biomarkers in the ISF as well as synchronized transdermal drug delivery by this single-chip multifunctional platform.

3D spinel-nanowire structured stainless steel is created via a single heating step, which in turn serves as an anode material in Li-ion batteries, exhibiting long and stable cycle life.

A novel 3D composite cathode structure, comprised of MnCr2O4spinel-based nanowires, is hereby presented. The reagentless self-seeded spinel-based nanowires are synthesized using an extremely simple, one-step, growth process that is comprised of 5% hydrogen in nitrogen at atmospheric pressure, under 1100°C, without any external catalyst or reagent. This simple one-step process allows the density-controlled growth of highly crystalline spinel nanowires directly from common stainless steel mesh substrates, which acts both as reagents source and as a current collector. Electrochemical measurements show that this cathode exhibits high capacity (>230 mA h/g), stable cyclability (>370 cycles), high coulombic efficiency (>99%) and high rate performance (>2C). The novel 3D composite cathode structure exhibits several major advantages over conventional 2D cathodes, both in terms of the synthesis process, cost-effectiveness and in terms of electrochemical performance enhancement possibilities.

New, higher-capacity materials are required in order to address the growing need for batteries with greater energy density and longer cycle life for modern applications. We present here a study of silicon-nanowire (SiNW) anodes, synthesized via a novel, catalysts free and scalable chemical vapor deposition (CVD) on stainless-steel mesh. This is a continuation to our previous paper (Harpak et al., Nano Lett. (2019) http://pubs.acs.org/doi/10.1021/acs.nanolett.8b05127) that describes the progress we recently made. The study is focused on the adaptation of the SiNW anode in various large-scale configurations. Our research efforts have resulted in the successful scale-up of the silicon anode from Si/Li half-cells with high areal capacity of 14 mAh cm[?]2, to coin cells with commercial cathodes, industrial 1/3AAA cells and proof-of-concept multilayered pouch cells. Testing of our anodes in cylindrical cells demonstrated the applicability of these anodes in commercial lithium-ion batteries that can run for hundreds of cycles, withstanding fast charge and subzero temperatures. An all-solid Si/polymer electrolyte/NCA cell is also demonstrated as a proof of concept (POC). We assign the major degradation mechanism of the SiNW anodes to the growth of the SEI thickness and impedance during cycling. We found that the depth of lithiation/delithiation and the voltage profile of the cell significantly affect cell's stability.

New, higher-capacity materials are required in order to address the growing need for batteries with greater energy density and longer cycle life for modern applications. We present here a study of silicon-nanowire (SiNW) anodes, synthesized via a novel, catalysts free and scalable chemical vapor deposition (CVD) on stainless-steel mesh. This is a continuation to our previous paper (Harpak et al., Nano Lett.(2019) http://pubs.acs.org/doi/10.1021/acs.nanolett.8b05127) that describes the progress we recently made. The study is focused on the adaptation of the SiNW anode in various large-scale configurations. Our research efforts have resulted in the successful scale-up of the silicon anode from Si/Li half-cells with high areal capacity of 14 mAh cm−2, to coin cells with commercial cathodes, industrial 1/3AAA cells and proof-of-concept multilayered pouch cells. Testing of our anodes in cylindrical cells demonstrated the applicability of these anodes in commercial lithium-ion batteries that can run for hundreds of cycles, withstanding fast charge and subzero temperatures. An all-solid Si/polymer electrolyte/NCA cell is also demonstrated as a proof of concept (POC). We assign the major degradation mechanism of the SiNW anodes to the growth of the SEI thickness and impedance during cycling. We found that the depth of lithiation/delithiation and the voltage profile of the cell significantly affect cell’s stability.