Carbon Nanofiber Concrete for Damage Detection of Infrastructure

Conductive nanofiller-modified composites have received a lot of attention from the structural health monitoring (SHM) research community in recent years because these materials are piezoresistive (i.e. they have deformation and damage-dependent electrical conductivity) and are therefore self-sensing. To date, the vast majority of work in this area has utilized direct current (DC) interrogation to identify and/or localize damage. While this approach has been met with much success, it is also well known that nanofiller-modified composites possess frequency-dependent electrical behavior. This behavior can be roughly modeled as a parallel resistor-capacitor circuit. However, much less work has been done to explore the potential this frequency-dependent behavior for damage detection. To this end, the work herein presented covers some preliminary results which leverage high-frequency electrical interrogation for damage detection. More specifically, carbon nanofiber (CNF)/epoxy specimens are produced and connected to an external inductor in both series and parallel configurations. Because the CNF/epoxy electrically behaves like a resistor-capacitor circuit, the inclusion of an inductor enables electrical resonance to be achieved. Changes in resonant frequency are then used for rudimentary damage detection. These preliminary results indicate that the potential of SHM via the piezoresistive effect in nanofiller-modified composites can be considerably expanded by leveraging alternating current (AC) interrogation and resonant frequency principles.

Download Full-text

Cytocompatibility of Carbon Nanofiber Materials for Neural Applications

MRS Proceedings ◽

10.1557/proc-774-o7.35 ◽

2003 ◽

Vol 774 ◽

Author(s):

Janice L. McKenzie ◽

Michael C. Waid ◽

Riyi Shi ◽

Thomas J. Webster

Keyword(s):

Carbon Fiber ◽

Surface Energy ◽

Carbon Nanofibers ◽

Carbon Fibers ◽

Carbon Nanofiber ◽

Fiber Composite ◽

Scar Tissue ◽

Pc 12 Cells ◽

Low Surface Energy ◽

Poly Carbonate

AbstractSince the cytocompatibility of carbon nanofibers with respect to neural applications remains largely uninvestigated, the objective of the present in vitro study was to determine cytocompatibility properties of formulations containing carbon nanofibers. Carbon fiber substrates were prepared from four different types of carbon fibers, two with nanoscale diameters (nanophase, or less than or equal to 100 nm) and two with conventional diameters (or greater than 200 nm). Within these two categories, both a high and a low surface energy fiber were investigated and tested. Astrocytes (glial scar tissue-forming cells) and pheochromocytoma cells (PC-12; neuronal-like cells) were seeded separately onto the substrates. Results provided the first evidence that astrocytes preferentially adhered on the carbon fiber that had the largest diameter and the lowest surface energy. PC-12 cells exhibited the most neurites on the carbon fiber with nanodimensions and low surface energy. These results may indicate that PC-12 cells prefer nanoscale carbon fibers while astrocytes prefer conventional scale fibers. A composite was formed from poly-carbonate urethane and the 60 nm carbon fiber. Composite substrates were thus formed using different weight percentages of this fiber in the polymer matrix. Increased astrocyte adherence and PC-12 neurite density corresponded to decreasing amounts of the carbon nanofibers in the poly-carbonate urethane matrices. Controlling carbon fiber diameter may be an approach for increasing implant contact with neurons and decreasing scar tissue formation.

Download Full-text

Cytocompatibility and Material Properties of Poly-carbonate Urethane/Carbon Nanofiber Composites for Neural Applications

MRS Proceedings ◽

10.1557/proc-774-o7.30 ◽

2003 ◽

Vol 774 ◽

Author(s):

Janice L. McKenzie ◽

Michael C. Waid ◽

Riyi Shi ◽

Thomas J. Webster

Keyword(s):

Mechanical Properties ◽

Carbon Nanofibers ◽

Material Properties ◽

Carbon Nanofiber ◽

Scar Tissue ◽

Tissue Response ◽

Positive Interactions ◽

Weight Percentage ◽

Poly Carbonate

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.

Download Full-text