Noe Alvarez

• PhD
• Assistant Professor at University of Cincinnati

Carbon nanotubes (CNTs) are well known for their flexibility, electrical conductivity and chemical inertness, however their use as biorecognition elements is limited due to multiple fabrication and interface aspects. Among them those related to their uniformity and stability of the CNT assemblies employed as microelectrodes. Although CNTs have show...

Voltammetric methods hold promise for the rapid and sensitive quantification ofmelatonin. This study reports the direct electrochemical quantification of melatonin using carbonnanotube (CNT) fiber cross-sections as microelectrodes. Six identical highly densified CNT fibercross-sections were employed to quantify melatonin in the range of 0.05–100 µM...

Flexible and biocompatible microwires are generally employed for biomedical implants in medicine, more specifically in neuroscience. These microwires used as electrodes need to be chemically inert and electrically conducting in order to record and stimulate the electrical activity of neurons in the nervous system. The electrodes available today are...

Carbon nanotubes (CNT) sheet is a new type of nonwoven fabric that is being evaluated for different applications. This article presents the first friction-based investigation of the use of CNT sheet as a dust shield. The focus application is for shielding future machinery on the moon from lunar dust. Lunar dust is strongly abrasive; it adheres to a...

Electrode miniaturization is an alternative path for the development of sensitive electrochemical sensors. The low charging current, enhanced mass transport and their suitability to be employed in resistive mediums has made microelectrodes attractive for detection of biomolecules. Carbon nanotubes (CNTs) are unique nanomaterials with high electrica...

Quantification of lead particulates requires laborious sample acidification and/or digestion in acidic environment, therefore lead quantification is limited to laboratories with trained personnel and expensive instrumentation. These technologies are not easily accessible to the public, and the large number of portable methods available to public to...

The unique electrical properties of carbon nanotubes (CNTs) are highly desired in many technological applications. Unfortunately, in practice, the electrical conductivity of most CNTs and their assemblies has fallen short of expectations. One reason for this poor performance is that electrical resistance develops at the interface between carbon nan...

Carbon nanotubes can be considered as a chemically stable material with exceptional electrical and thermal conductive properties. Electrically conductive applications of carbon nanotubes (CNTs) have been limited by several factors, among them a lack of robust connections to metal surfaces is significant affecting for CNT widespread applications. In...

Carbon Nanotubes (CNTs) are excellent materials because of their unique physical and chemical properties. Though catalyst nanoparticles preparation from thin film catalysts are common but premade catalysts nanoparticles in liquid phase has control over the size and composition which control the diameter and length of CNTs. Here, we report the synth...

Understanding brain function and neurological disorders are essential to develop therapeutic strategies such as neuropharmacological medications and implantable biomedical tools to treat brain-related disorders. Implantable neural electrodes can deliver in-depth knowledge of brain activity and disorders by recording real-time brain signals. Epileps...

Electrochemical methods, such as square wave voltammetry, can detect lead in drinking water. However, these methods can only detect lead ions. Lead contamination in drinking water can be from both Pb ²⁺ and particulate lead. Particulate lead comes from the inner walls of lead pipes and is often called lead scale. Lead scales forms from years of wat...

Implantable micro electrodes are generally employed to record and stimulate electrical activity of neurons in the nervous system. Most of the electrodes available today are made of metals and silicon that lack required flexibility resulting on a mechanical mismatch between soft tissues and rigid metals which induces faster biofouling and inconsiste...

Detection of hydrogen peroxide (H 2 O 2 ) has practical significance in various fields, including pharmaceutical, clinical and food industries. The enzyme based H 2 O 2 biosensors allow for the detection at lower potentials, thus avoiding possible interference from reducing agents. However, this type of sensors is inherently less stable, difficult...

The presence of particulate Pb in tap water has been a limiting factor in the design of accurate and portable platforms for quantifying this toxic metal. Convenient and affordable electrochemical techniques are blind toward particulate species and thus require addition of reagents and additional chemical processing such as sample acidification. Thi...

The demand for electrically insulated microwires and microfibers in biomedical applications is rapidly increasing. Polymer protective coatings with high electrical resistivity, good chemical resistance, and a long shelf-life are critical to ensure continuous device operation during chronic applications. As soft and flexible electrodes can minimize...

Aluminum oxide is an important ceramic material for coatings and catalyst support for high-temperature applications. In this work, spherical aluminum oxide (AlOx) nanoparticles (NPs) are synthesized via the thermal decomposition of aluminum oleate using oleic acid as a stabilizing agent. X-ray diffraction analysis confirms its crystallization to γ-...

Bimetallic oxide nanoparticles are promising materials due to their diverse physical properties. Herein, we synthesized bimetallic aluminum oxides (AlOx)- iron oxides (FeOx) nanoparticles with different shapes and elemental compositions by...

Catalytic decomposition of methane (CDM) to H2 and multiwalled carbon nanotubes (MWCNTs) was achieved by a nanocrystalline Cr-doped ferrite (FeCr) catalyst at 500 °C and atmospheric pressure with minor cofed CO. The exothermic Boudouard reaction increased the temperature and H2 from CDM at catalyst surface that induced Fe²⁺ reduction to Fe⁰. The Fe...

Exposure to lead, a toxic heavy metal, in drinking water is a worldwide problem. Lead leaching from lead service lines, the main contamination source, and other plumbing materials is controlled by the plumbosolvency of water. Square wave anodic stripping voltammetry (SWASV) has been greatly explored as a rapid and portable technique for the detecti...

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electrochemically active. A particular challenge in this field has been the ability to conduct electrochemical studies selectively at the open-ends of CNTs, without measuring contributions from the sidewa...

Implantable neural electrodes are generally used to record the electrical activity of neurons and to stimulate neurons in the nervous system. Biofouling triggered by inflammatory responses can dramatically affect the performance of neural electrodes, resulting in decreased signal sensitivity and consistency over time. Thus, long-term clinical appli...

Carbon nanotubes (CNTs) offer unique properties that have the potential to address multiple issues in industry and material sciences. Although many synthesis methods have been developed, it remains difficult to control CNT characteristics. Here, with the goal of achieving such control, we report a bottom-up process for CNT synthesis in which monola...

The exceptional physical properties of carbon nanotubes (CNTs) have the potential to transform materials science and various industrial applications. However, to exploit their unique properties in carbon-based electronics, CNTs regularly need to be chemically interfaced with metals. Although CNTs can be directly synthesized on metal substrates, thi...

Incorporating the nanoscale properties of carbon nanotubes (CNTs) and their assemblies into macroscopic materials is at the forefront of scientific innovation. The electrical conductivity, chemical inertness, and large aspect ratios of these cylindrical structures make them ideal electrode materials for electrochemical studies. The ability to assem...

Lead contamination of drinking water is a concern to all inhabitants of old cities where lead pipes and soldering are still present. Simple on-site electrochemical detection methods are promising technologies that have gained attention recently. However, conventional electrochemical techniques only quantify soluble forms of lead in water without ac...

Background: Much progress has been made at the interface between neural tissue and electrodes for neurophysiology. However, there continues to be a need for novel materials that integrate well with the nervous system and facilitate neural recordings with longer-term sustainability and stability. Such materials have the potential to improve clinica...

In this work, a carbon nanotube microelectrode set (CNT µ-ES) was modified, in which three electrodes based on highly densified carbon nanotube fiber (HD-CNTf) cross-sections (length ~40 μm) were embedded in an inert polymer matrix with exposed open-ended CNTs at the interface. An HD-CNTf cross-section (∼40 μm diameter) electrochemically modified w...

Assembling carbon nanotubes (CNTs) into macroscopic materials allows multiple applications that takes advantage of their physical properties. Specifically, the synthesis, fiber assembly, polymer coating and application of CNTs as microelectrodes has allowed us explore physiological applications as well as sensor development. This talk will summariz...

A comparative experimental study between advanced carbon nanostructured electrodes, in similar hydrogen uptake/desorption conditions, is investigated making use of the recent molecular beam-thermal desorption spectrometry. This technique is used for monitoring hydrogen uptake and release from different carbon electrocatalysts: 3D-graphene, single-w...

The thermal conductivities of a low-defect 3D graphene materials synthesized by CVD processes have been investigated experimentally. The materials investigated were prepared using pure Ni powdered catalyst (giving graphene paper, GP, so called because the bulk structure is a paper, with a 3-dimensional interconnected graphene microstructure), or ni...

Heavy metal contamination of drinking water is a major global issue. Research reports across the globe show contamination of heavy metals higher than the set standards of the World Health Organization (WHO) and US Environmental Protection Agency (EPA). To our knowledge, no electrochemical sensor for heavy metals with parts per trillion (PPT) limits...

Recordings and stimulations of neuronal electrical activity is a topic of great interest in neuroscience. Many recording techniques, and even treatment of neurological disorders can benefit from a microelectrode that is flexible, chemically inert, electrically conducting, and preferentially transfers electrons via capacitive charge-injection. Comme...

A nanocrystalline chromium-doped ferrite (FeCr) catalyst was shown to coproduce H2 and multiwalled carbon nanotubes (MWCNTs) during water gas shift (WGS) reaction in a H2-permselective zeolite membrane reactor (MR) at reaction pressures of ~20 bar. The FeCr catalyst was further demonstrated in the synthesis of highly crystalline and dimensionally u...

Nowadays lead pipes are still present in many houses and could be a potential source of this metal in drinking water. Modern polyvinyl chloride pipes also contain compounds of lead, that can be leached from them, causing an increase of Pb concentration in drinking water. That is why regular and simple testing of tap water is necessary to avoid lead...

Carbon nanotubes (CNTs) are widely used in neuroscience research for its excellent properties such as high conductivity, electrochemical stability, biocompatibility, mechanical compatibility with tissues, tunable mechanical and chemical properties. CNTs are investigating for its performance as neuronal scaffolds to support neural tissues, neuron gr...

The heavy metal lead has been a pollutant in our environment for many centuries and at low concentrations, lead can damage the human central nervous system, liver, kidney, and cardiovascular system and cause physiological and neurological problems in developing children who are most susceptible to lead poisoning. Lead in drinking water is currently...

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electro-chemically active. A particular challenge in this field has been the ability to conduct electrochemical studies at the open ends of CNTs, without measuring contributions from the sidewalls. Among...

Carbon Nanotubes (CNTs) are the emerging materials because of their extraordinary physical and chemical properties. Diverse applications, such as chemical and biochemical sensors, electronic devices, nanocontainer lithium ion batteries, thermally stable materials, and many others have been proposed and tested. The properties of carbon nanotubes dep...

Assembling carbon nanotubes (CNTs) into macroscopic materials allows multiple applications that take advantage of their unique physical properties. Specifically, the synthesis, fiber assembly, polymer coating and application of CNTs as microelectrodes in electrochemical detection and quantification of heavy metals and neurotransmitters will be pres...

Nanochannels, such as ion channels, are present in many biological functions and can control ion flow through the channel for cellular function. The trigger of the ion flow can be achieved through changes of pH, voltage, or others variables. Ion channels are important to studying some diseases, however, biological ion channels are embedded in fragi...

Cadmium (Cd) is a non-essential toxic heavy metal. Human exposure to Cd occurs from multiple sources, including diet, tobacco smoke, fossil fuel combustion, and variously contaminated environments. This work reports a rapid method for Cd ²⁺ detection in simulated urine samples containing glucose (GLC) and actual human urine using the electrochemica...

Three-dimensional (3D) graphene has become an area of great interest due to its unique properties, and different synthesis routes and structures have been reported in the literature. However, the challenges of retaining high quality, scaling up and improving economic feasibility are apparent. Here we describe 3D graphene sheet (3DGS), which is a no...

Electroanalytical methods can be used for the reliable detection of the toxic heavy metal lead in drinking water samples. Inkjet printed electrodes have potential for the rapid and affordable assessment of drinking water. Researchers have shown the electrochemical sensing applicability of inkjet printed electrodes. In this work, Pb 2+ was detected...

Cadmium (Cd) is a non-essential toxic heavy metal. Human exposure to Cd occurs from multiple sources, including diet, tobacco smoke, fossil fuel combustion, and various contaminated sources. This work reports a rapid method for Cd²⁺ detection in simulated urine samples containing glucose (GLC) and human urine using the electrochemical technique of...

Electrochemistry at open ends and sidewalls of carbon nanotubes (CNTs) has been under debate, with opposing viewpoints as to which sites are more electrochemically active. A particular challenge in this field has been the ability to conduct electrochemical studies at the open ends of CNTs, without measuring contributions from the sidewalls. Here, w...

In this paper, we present the results of a study related to fabrication of polymer-aligned carbon nanotube (CNT) composites made with different thermoplastic polymers. These composites have been manufactured by employing a simple two-step process using the internal resistive heating approach. The resulting composites have shown improved tensile str...

In this work, we describe a simple approach for the synthesis of three-dimensional graphene (3D-G) - carbon nanotube (CNT) hybrid fibers via Chemical Vapor Deposition (CVD). The obtained hybrid fiber was employed as a free-standing current collector in an electrochemical supercapacitor thus avoiding any conductive additives or metals. The amount of...

Carbon nanotube (CNT) fiber electrodes have become increasingly popular electrode materials for neurotransmitter detection with fast-scan cyclic voltammetry (FSCV). The unique properties of CNT fiber electrodes like increased electron transfer, sensitivity, waveform application frequency independence, and resistance to fouling make them ideal biolo...

Dry-spun Carbon Nanotube (CNT) fibers were surface-modified by atmospheric pressure oxygen plasma functionalization using a well controlled and continuous process. The fibers were characterized by scanning electron microscopy (SEM), Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). It was found from the conducted electrochemical measu...

Spinnable carbon nanotubes (CNTs) are useful formats for studying physical properties of CNT fiber assemblies in their pristine states. They are free of catalyst, uniform in length, with a comparatively narrow diameter distribution, and their assembly into thread does not require additional chemicals or solvents. Good quality drawable CNT arrays ca...

Issues associated with the dry spinning process were explored and addressed in this paper. Post-treatment of dry-spun Carbon Nanotube (CNT) fibers frequently includes solvent densification. This procedure was modified in our work to enhance mechanical strength of the fiber. The effect of n-Methyl-2-Pyrrolidone (NMP) as a densifying solvent was stud...

The acoustic absorption of carbon nanotube (CNT) absorbers made of vertically aligned CNT forests is investigated experimentally in an impedance tube using the two-microphone method with normal incidence. Results show that a 3 mm thick forest of CNTs can provide upto 10% acoustic absorption within the frequency range 125 Hz – 4 kHz. Theoretical pre...

Membrane filtration is one of the most reliable methods for water treatment. However, wider application is limited due to biofouling caused by accumulation of microorganisms on the membrane surface. This report details a heatable carbon nanotube composite membrane with self-cleaning properties for sustainable recovery from biofouling. Microfiltrati...

Mass spectrometry continues to tackle many complicated tasks, and ongoing research seeks to simplify its instrumentation as well as sampling. The desorption electrospray ionization (DESI) source was the first ambient ionization source to function without extensive gas requirements and chromatography. Electrospray techniques generally have low effic...

Multiple applications of carbon nanotubes (CNTs) require their assembly into macroscopic materials: films, sheets, and ribbons. Most of these macro-materials are flexible thin structures and need to be cut to micrometer dimensions. Laser cutting has emerged as one of the best pressure-free alternative methods, providing accuracy and uniformity. We...

In this work, all three electrodes in an electrochemical cell were fabricated based on carbon nanotube (CNT) thread. CNT thread partially insulated with a thin polystyrene coating to define the microelectrode area was used as the working electrode; bare CNT thread was used as the auxiliary electrode; and a micro quasi-reference electrode was fabric...

The alignment of different carbon nanotube (CNT) structures has been studied extensively using varying techniques. Most of these techniques however do not present a true three-dimensional (3D) representation of the orientation of the material. In this work, the orientation distribution functions obtained from X-ray pole figures for different CNT st...

The unique physical properties of individual Carbon Nanotubes (CNTs) surpass the properties of many advanced materials available today. Due to their large surface area, chemical stability, and electrical conductivity, they are the most promising candidates for a large number of electroanalytical applications. A material for these applications requi...

Graphene foam is one kind of network of three dimensional (3D) graphene, which inherits the properties of two dimensional graphene and overcomes the aggregation/stacking of graphene sheets. In this work, graphene foam has been characterized by scanning electron microscopy and Raman spectroscopy. A graphene foam electrode was evaluated as a new elec...

Vertically aligned Carbon Nanotube (CNT) arrays are synthesized directly on CNT sheets used as substrates by plasma enhanced chemical vapor deposition (PECVD) in NH3 plasma environment. The resulting 3-D nanostructured, N-doped CNT (NCNT) architecture combines high conductivity and superior mechanical properties of CNT sheets with porous structure...

Flexible micro-supercapacitors (MSCs) are constructed by 3D graphene from chemical vapor deposition. Without using any binder or metal current collector, the as-prepared 3D graphene MSC exhibits good flexibility, excellent cyclic life, and high areal capacitance of 1.5 mF cm(-2) at a scan rate of 10 V s(-1) . The electrochemical performance is furt...

Previous investigations have shown that a 3-mm-high carbon nanotube (CNT) forest has an acoustic absorption coefficient of about 5-10% within the frequency range 125 Hz-4 kHz, which is above that of conventional acoustic materials on a per-mass basis. It was hypothesised that a CNT array of greater height, lower density, and with a non-uniform arra...

Effects of nanomaterial post-process treatments on the RF performance of a variety of carbon nanotube patch antennas are explored through fabrication and measurement. A discussion of the physical and electrical mechanisms underpinning the results of these measurements is presented. The sparse application of metal nanoparticles to carbon nanotube sh...

Freshwater contamination during extensive algae blooms with their cyanotoxins represents a significant global concern for public health. In 2014, algae blooms have significantly affected drinking water supply in the Toledo (OH, USA). Due to similar threatening incidents, the U.S. Environmental Protection Agency (USEPA) was urged to release a ten-da...

Individual Carbon Nanotubes (CNTs) have a great mechanical strength that needs to be transferred into macroscopic fiber assemblies. One approach to improve the mechanical strength of the CNT assemblies is by creating covalent bonding among their individual CNT building blocks. Chemical cross-linking of multiwall CNTs (MWCNTs) within the fiber has s...

Improved CNT/epoxy composites composed of dry-drawn, aligned and functionalized CNTs were fabricated. Dry-drawn multi-walled carbon nanotube (MWNTs) were functionalized by atmospheric pressure He/O2 based plasma during the manufacturing of the CNT sheets and epoxy resin dissolved in solvent was sprayed during the manufacturing. The extent of CNT fu...

Graphene foam (GF) is a three-dimensional (3D) graphene structure that has been intensively studied as electrode materials for energy storage applications. The porous structure and seamlessly connected graphene flakes made GF a promising electrode material for supercapacitors and batteries. However, the electrical conductivity of GF is still unsati...

Carbon nanotubes (CNTs) are a promising material for many applications, due to their extraordinary properties. Some of these properties vary in relation to the diameter of the nanotubes; thus, precise control of CNT diameter can be critical. Porous anodic alumina (PAA) membranes have been successfully used to template electrodeposited catalyst. How...

Electronic Supplementary Information (ESI) available: Supplementary information includescomplete histograms of the diameter, examples of the TEM images used to collect the diameterdata, and the recipe used to synthesize the carbon nanotubes. Supplementary material 1

Carbon nanotube (CNT) film was evaluated as an optically transparent electrode (OTE) for thin layer spectroelectrochemsitry. Chemically inert CNT arrays were synthesized by chemical vapor deposition (CVD) using thin films of Fe and Co as catalysts. Vertically aligned CNT arrays were drawn onto a quartz slide to form CNT films that constituted the O...

We have examined the anisotropic terahertz response of highly aligned single-wall, double-wall, and multiwall carbon nanotubes and quantitatively characterized their performance as low-cost terahertz polarizers.

Syntheses of multifunctional structures, both in two-dimensional and three-dimensional space, are essential for advanced graphene applications. A variety of graphene-based materials has been reported in recent years, but combining their excellent mechanical and electrical properties in a bulk form has not been entirely achieved. Here, we report the...

Nanotubes are a unique class of materials because their properties depend not only on their composition but also on their geometry. The diameter, number of walls, length, chirality, van der Waals forces, and quality all affect the properties and performance of nanotubes. This dependence on geometry is what makes scaling-up nanotubes to form bulk ma...

Carbon nanotubes (CNTs) have been at the frontier of nanotechnology research for the past two decades. The interest in CNTs is due to their unique physical and chemical properties, which surpass those of most other materials. To put CNTs into macroscale applications, the nanotubes can be spun to form continuous fiber materials. Thus far, the proper...