This study presents a smart structural health monitoring (SHM) framework that integrates stimuli-responsive nano-carbon sensing materials with system-level, data-driven interpretation. The key novelty lies in reframing the intrinsic nonlinearity and history dependence of nano-carbon sensors, typically treated as limitations, as exploitable characteristics within a coupled material-structure sensing paradigm, enabling quantitative impact monitoring without material-level stabilization. Spray-deposited nano-carbon strain sensors (NCSS), exhibiting intrinsic piezoresistive and nonlinear electrical responses under mechanical impact, are deployed as lightweight and scalable sensing layers on fiber-reinforced polymer (FRP) composite structures. Rather than suppressing sensor nonlinearity and signal variability through extensive calibration, the proposed framework leveraged these characteristics at the system level by combining distributed sensing architectures with temporal learning models. A long short-term memory (LSTM) neural network was employed to map history-dependent and anisotropic material responses to physically meaningful impact parameters, enabling simultaneous impact localization and force estimation. A total of 532 impact tests were conducted on FRP panels equipped with a U-shaped NCSS network, and their performance was benchmarked against a conventional linear regression (LR) approach. The LR model exhibited a mean radial localization error (MRE) of 43.6 mm and a mean absolute percentage error (MAPE) of 62.5% in force estimation. In contrast, the LSTM-based framework achieved a localization error of 4.52 mm and reduced the force estimation error to 9.59% MAPE by capturing the nonlinear and spatially coupled sensor responses. These results demonstrate that quantitative impact monitoring can be achieved by treating sensing as a coupled material structure system problem, rather than as a material-level signal stabilization task. Owing to its surface-deployable, low-cost, and scalable characteristics, the proposed framework provides a practical pathway for deployable smart SHM systems in aerospace, automotive, and civil composite structures.

More than one million firefighters work in the United States. The standard fire (SF) coat, used by the firefighters, had been in place for many years. Our research team was entrusted with the job of designing a new coat radically different from the SF coat. In the first year of the project, we designed a cooling system (CS) coat with carbon nanotube-based fabric, two pouches inside the coat, accommodating coolants and fans. We spent one year on the new coat making sure that fans run, and coolants remain unspent while firefighters work inside a live burn facility for a specified length of time. We christened the state-of-theart coat that eventually involved as Lion’s cooling system (LC) coat. The main objective of our research was to compare SF and LC coats on gait and postural balance of firefighters. Underlying our research mission was the goal to show that the LC coat is not inferior to the SF coat on gait and postural balance. The mission was successful.

To address the challenges of biopsy and intratumoral drug delivery using microdevices, a miniature multifunctional tethered device that has tissue cutting, biopsy and drug delivery capabilities is presented in this paper. The cutting module in the prototype is hydraulically powered and has an outside diameter (OD) of 2 mm at the tip and a cutter attached to 500 µm drive shaft. The hydraulic micromotor prototype was fabricated using micro additive manufacturing. It was tested using a benchtop set-up and had an average speed greater than 100,000 RPM at a water flowrate of 45 mL/min and a speed of about 34,000 RPM at 15 mL/min flowrate. This micromotor design was numerically modeled using 3D-transient simulations in ANSYS CFX to determine its performance characteristics and internal resistance. Preliminary testing was performed using cutting modules with five cutter geometries on agar tissue phantoms of different concentrations and other biological materials. The dissection ability of the cutting module, its ability to deliver particles, and collect biopsy samples were successfully demonstrated. Scaling the 2 mm OD device further, a 1 mm OD micromotor, with a nominal output shaft diameter of 250 µm, was fabricated and operated with air establishing the proof of concept.

The study aims to create a turnout gear coat liner prototype with an active cooling system and evaluate its performance with an Infrared (IR) camera, CO2, and sweat mannequin. The final fabric was made by integrating the Carbon Nanotube (CNT) sheet into the existing liner layup materials. As a result, 1) the study successfully created the first prototype cooling system embedded coat,which has a core guard, cooling apparatus with fans, filter, coolants, battery,and turn-on/off switch. 2) The study evaluated the cooling system's effectiveness using an IR camera and a CO2 sensor with variations of blower fans and coolants to select the best cooling materials. 3) The National Institute for Occupational Safety & Health results clearly show the effectiveness of integrated CNT-embedded cooling systems. The study confirmed that the performance of the active cooling system works better than the standard liner at ambient temperature and heated conditions.

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 all surfaces and causes wear. The absence of an atmosphere and water on the moon, along with its low gravity, and electrostatic adhesion exacerbates the issue of lunar dust, which affects all surfaces, including machinery and human apparel. Friction testing was performed to represent the effect of abrasion occurring on a garment surface while astronauts are working on the moon. The coefficients of static and sliding friction between two CNT sheets, held against each other by a weight, were 0.6 and 0.45, respectively. The presence of lunar regolith simulant reduced the friction coefficients between the two CNT sheets by 33% and 22% for static and sliding friction, respectively. The dust in the sheets was easily cleaned with dry wiping and compressed air, showing no requirement to use water for cleaning in space applications. However, the CNT sheets experienced wear after repeated friction tests. The CNT sheets passed the flammability test standards ASTM D6413/D6413M-15 and NPFA 1971 for applications under extreme heat conditions. Thus, CNT sheet can be considered as a multi-functional material for lunar applications, with shielding protection against dust and electromagnetic waves, and resistance to high temperatures.

Aligned with the medical device industry's trend of miniaturization, academic and commercial researchers are constantly attempting to reduce device sizes. Many applications require miniature actuators (2 mm range) to perform mechanical work; however, biocompatible micromotors are not readily available. To that end, a hydraulic motor-driven cutting module that aims to combine cutting and drug delivery is presented. The hydraulic motor prototype developed has an outside diameter (OD) of ~4 mm (twice the target size) and a 1 mm drive shaft to attach a cutter. Four different designs were explored and fabricated using additive manufacturing. The benchtop experimental data of the prototypes are presented herein. For the prototype motor with fluid inlet perpendicular to the blades, the average angular velocity was 10,593 RPM at a flowrate of 3.6 mL/s and 42,597 RPM at 10.1 mL/s. This design was numerically modeled using 3D-transient simulations in ANSYS CFX (version 2022 R2) to determine the performance characteristics and the internal resistance of the motor. Simplified mathematical models were also used to compute and compare the peak torque with the simulation estimates. The viability of current design represents a crucial milestone in scaling the hydraulic motor to a 2 mm OD to power a microcutter.

This research reports the development of 3D carbon nanostructures that can provide unique capabilities for manufacturing carbon nanotube (CNT) electronic components, electrochemical probes, biosensors, and tissue scaffolds. The shaped CNT arrays were grown on patterned catalytic substrate by chemical vapor deposition (CVD) method. The new fabrication process for catalyst patterning based on combination of nanoimprint lithography (NIL), magnetron sputtering, and reactive etching techniques was studied. The optimal process parameters for each technique were evaluated. The catalyst was made by deposition of Fe and Co nanoparticles over an alumina support layer on a Si/SiO2 substrate. The metal particles were deposited using direct current (DC) magnetron sputtering technique, with a particle ranging from 6 nm to 12 nm and density from 70 to 1000 particles/micron. The Alumina layer was deposited by radio frequency (RF) and reactive pulsed DC sputtering, and the effect of sputtering parameters on surface roughness was studied. The pattern was developed by thermal NIL using Si master-molds with PMMA and NRX1025 polymers as thermal resists. Catalyst patterns of lines, dots, and holes ranging from 70 nm to 500 nm were produced and characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Vertically aligned CNTs were successfully grown on patterned catalyst and their quality was evaluated by SEM and micro-Raman. The results confirm that the new fabrication process has the ability to control the size and shape of CNT arrays with superior quality.

A carbon nanotube (CNT) sheet is a nonwoven fabric that is being evaluated for use in different textile applications. Several properties of pristine CNT sheets and CNT sheets coated with a polysilazane sealant and coating were measured and compared in the paper. The polysilazane coating is used to reduce the shedding of CNT fibers from the sheet when the sheet is in contact with surfaces. Most fabrics show some shedding of fibers during the washing or abrasion of the fabric. This study showed that the coating reduces the shedding of fibers from CNT fabric. The coating also increased the flame resistance of the fabric. The pristine and coated sheets both have low strength but high strain to failure. The pristine and coated CNT sheet densities are 0.48 g/cc and 0.65 g/cc, respectively. The pristine CNT sheet is approximately 27 μ thick. The coated sheet is approximately 24 μ thick. The coating may have densified the sheet, making it thinner. The thickness of the compliant sheets was difficult to measure and is a source of error in the properties. Characterization results are given in this paper. The results are for comparison purposes and not to establish material properties data. Possible applications for CNT sheets are briefly discussed.

Miniaturization of multifunctional instruments is key to evolving less invasive medical procedures. The current work outlines steps towards developing a miniature motor to power a cutting tool of a millimeter-scale robot/device (target outside diameter ~2 mm) for minimally invasive procedures. Multiple motor concepts were explored and ranked using a Pugh matrix. The single-rotor hydraulic design was deemed most viable for prototyping and scale-down to the target size. Prototypes were manufactured to be progressively smaller using additive manufacturing. The smallest prototype fabricated was 2:1 scale of the desired final size with a 2 mm outside diameter (OD) rotor and a device OD of 4 mm. The scaled prototypes with an 8 mm rotor were lab tested and achieved average speeds of 5000–6000 RPM at a flowrate of 15–18 mL/s and 45 PSI water pressure. Ansys CFX was used as a design tool to explore the parameter space and 3D transient simulations were implemented using the immersed solid method. The predicted rotor RPM from the modeling matched the experimental values within 3% error. The model was then used to develop performance curves for the miniature hydraulic motor. In summary, the single-rotor hydraulic design shows promise for miniaturization to the target 2 mm size.

Carbon nanotube (CNT) hybrid composites were formed by combining a CNT and silicone elastomer solution with Kevlar yarn, Kevlar fabric, and Kevlar veil materials. The integration of a CNT-silicone matrix with Kevlar yarn and fabric materials produced a composite with moderate electrical and thermal conductivity due to CNT fabric combined with the strength of Kevlar fabric or yarn. In the material synthesis, a notable difficulty was that the CNT-silicone did not bond strongly to the Kevlar. The composites passed the Vertical Flame Test ASTM D6413 and the Forced Air Oven Test NFPA 1971. These hybrid composites can have multiple applications in areas requiring favorable conductivity, strength, and flame and heat resistance. The application areas include firefighter apparel, military equipment, conductive/smart structures, and flexible electronics. The synthesis process used to manufacture CNT-silicone/Kevlar composites yielded composite sheets with an area of 2250 cm2. The process is scalable and customizable for the synthesis of CNT composites with tailored properties. Improvements in the bonding of CNT-silicone to Kevlar are being investigated.

Carbon nanotubes (CNTs) have extraordinary properties and are used for applications in various fields of engineering and research. Due to their unique combination of properties, such as good electrical and thermal conductivity and mechanical strength, there is an increasing demand to produce CNTs with enhanced and customized properties. CNTs are produced using different synthesis methods and have extraordinary properties individually at the nanotube scale. However, it is challenging to achieve these properties when CNTs are used to form macroscopic sheets, tapes, and yarns. To further improve the properties of macroscale forms of CNTs, various types of nanoparticles and microfibers can be integrated into the CNT materials. The nanoparticles and microfibers can be chosen to selectively enhance the properties of CNT materials at the macroscopic level. In this paper, we propose a technique to manufacture carbon hybrid materials (CHMs) by combining CNT non-woven fabric (in the form of sheets or tapes) with microfibers to form CNT-CF hybrid materials with new/improved properties. CHMs are formed by integrating or adding nanoparticles, microparticles, or fibers into the CNT sheet. The additive materials can be incorporated into the synthesis process from the inlet or the outlet of the reactor system. This paper focuses on CHMs produced using the gas phase pyrolysis method with microparticles/fibers integrated at the outlet of the reactor and continuous microfiber tapes integrated into the CNT sheet at the outlet using a tape feeding machine. After synthesis, characterizations such as microscopy and thermogravimetric analysis were used to study the morphology and composition of the CNTs, and examples for potential applications are discussed in this paper.

This work studies synthesis of carbon nanotube (CNT) sheet using the high temperature (1400 °C) floating catalyst chemical vapor deposition (FC-CVD) method. Three metallocenes—ferrocene, nickelocene, cobaltocene—and their combinations are used as precursors for metal catalysts in the synthesis process. For the carbon source, an alcohol fuel, a combination of methanol and n-hexane (9:1), is used. First, the metallocenes were dissolved in the alcohol fuel. Then, the fuel mixture was injected into a tube furnace using an ultrasonic atomizer with Ar/H2 carrier gas in a ratio of about 12/1. The synthesis of CNTs from a combination of two or three metallocenes reduces the percentage of metal catalyst impurity in the CNT sheet. However, there is an increase in structural defects in the CNTs when using mixtures of two or three metallocenes as catalysts. Furthermore, the specific electrical conductivity of the CNT sheet was highest when using a mixture of ferrocene and cobaltocene as the catalyst. Overall, the multi-catalyst method described enables tailoring certain properties of the CNT sheet. However, the standard ferrocene catalyst seems most appropriate for large-scale manufacturing at the lowest cost.

sock while Fig. 8(b) shows a low-density sock. Improved injection tuning could provide a continuous high-density sock. Our hypothesis is CHM fabric, Fig. 8(c) , can be manufactured at a higher rate and with customized properties using particle injection. Besides showing the need to improve the stability of the particle injection, which is mainly a mechanical design problem, this experiment also indicated that mixing ferrocene with the NPs and injecting them separately from the fuel seems to make the sock formation more uniform as compared to injecting Zn NPs with the fuel in the mixer. A higher percentage of NPs can be injected when they are mixed with ferrocene. The optimal ratio of NPs to ferrocene, and the possibilities to compound NP mixtures using different metals need to be investigated. Overall, the CHM process is an emerging technology and some of the first results evaluating this new process are presented in this paper.

Particulate Matter (PM) has become an important source of air pollution. We proposed a flexible and lightweight carbon nanotube (CNT) composite air filter for PM removal. The developed CNT filtering layers were fabricated using a floating catalyst chemical vapor deposition (FC-CVD) synthesis process and then combined with conventional filter fabrics to make a composite air filter. Filtration performance for CNT filtering layer alone and composited with other conventional filter fabrics for particles size 0.3 μm to 2.5 μm was investigated in this study. The CNT composite filter is highly hydrophobic, making it suitable for humid environments. The CNT composite filter with two layers of tissue CNT performed best and achieved a filtration efficiency over 90% with a modest pressure drop of ~290 Pa for a particle size of 2.5 μm. This CNT composite filter was tested over multiple cycles to ensure its reusability. The developed filter is very light weight and flexible and can be incorporated into textiles for wearable applications or used as a room filter.

High demand for electrochemical storage devices is increasing the need for high-performance batteries. A Zn-CO2 battery offers a promising solution for CO2 reduction as well as energy storage applications. For this study, a Zn-CO2 battery was fabricated using a Carbon Nanotube (CNT) sheet as a cathode and a Zn plate as an anode. The electrochemical activation technique was used to increase the surface area of the CNT electrode by roughly 4.5 times. Copper (Cu) as a catalyst was then deposited onto the activated CNT electrode using electrodeposition method and different Cu loadings were investigated to optimize CO2 reduction. The final assembled Zn-CO2 battery has a 1.6 V output voltage at a current density of 0.063 mA/cm2, which is higher than most devices reported in the literature. This study demonstrates the importance of activation process which enabled more catalyst loading on the cathode resulted in additional active sites for electroreduction process. This paper presents the activated CNT sheet as a promising cathode material for Zn-CO2 batteries.

This paper describes the characterization of carbon nanotube fabric or nanofabric. The nanofabric, has five fundamental properties: light weight, hydrophilic or hydrophobic, flame resistance, flexibility, and filterant. The nanofabric is formed by injecting a precursor aerosol into a high-temperature flow-through reactor. Nanofabric is collected on a drum from the exhuast. Hybrid nanofabric is synthesized by co-injection of a granulated carbon aerosol. Current fabrics used in firefighting might be supplemented with nanofabric or hybrid nanofabric to alleviate the dangers of airborne toxic chemicals and particles, along with assisting in heat management. The nanofabric survived longer in a flame test compared to traditional flame-resistant textiles.

Conventional gloves partially insulate against heat transfer from a hot external environment. They also prevent metabolic heat generated by the human body from escaping. Thus, gloves are a source of heat buildup and heat stress in workers. Heat stress can lead to hyperthermia. Described herein is a glove that cools using a carbon nanotube (CNT) fabric micro-liner and forced convection from a fan. A cold sink is assumed to be located in the glove to cool the convection air. This glove is called an active textile glove. CNT fabric has high thermal conductivity in the plane of the fabric, low thermal conductivity through its thickness, and a large surface area for convection cooling. Thus, the active textile glove can transfer heat from the hand to cooler air in the environment. This paper simulates the performance of a CNT-cooled glove using simple theoretical heat transfer models. Cooling was also demonstrated by testing the glove using a hot plate. Forced convection was found to provide the greatest cooling effect, with it working in synergy with the CNT fabric which aids in spreading heat. CNT fabric also acts as a shield from environmental dangers. The fabric is flame resistant, attenuates radio frequency waves, and prevents smoke particles and toxic chemicals from entering the glove. Testing illustrates the shielding properties of CNT fabric.

The paper describes the synthesis of carbon nanotube hybrid material and its post-processing treatment such as heat treatment of carbon nanotube (CNT) sheet to improve its properties for in textile applications. The CNT sheet is synthesized using the floating catalyst chemical vapor deposition (FCCVD) method. The floating catalyst method is a continuous process and can produce industrial scale nanotubes in a single step. The lightweight of the CNT material and its flexibility makes it a suitable candidate for textile and wearable applications. The synthesis process and applications of the new hybrid material are discussed along with the customization of the material.