Novel biomaterials: plasma-enabled nanostructures and functions

Material processing techniques utilizing low-temperature plasmas as the main process tool feature many unique capabilities for the fabrication of various nanostructured materials. As compared with the neutral-gas based techniques and methods, the plasma-based approaches offer higher levels of energy and flux controllability, often leading to higher quality of the fabricated nanomaterials and sometimes to the synthesis of the hierarchical materials with interesting properties. Among others, nanoscale biomaterials attract significant attention due to their special properties towards the biological materials (proteins, enzymes), living cells and tissues. This review briefly examines various approaches based on the use of low-temperature plasma environments to fabricate nanoscale biomaterials exhibiting high biological activity, biological inertness for drug delivery system, and other features of the biomaterials make them highly attractive. In particular, we briefly discuss the plasma-assisted fabrication of gold and silicon nanoparticles for bio-applications; carbon nanoparticles for bioimaging and cancer therapy; carbon nanotube-based platforms for enzyme production and bacteria growth control, and other applications of low-temperature plasmas in the production of biologically-active materials

Diamond Nanowire Synthesis, Properties and Applications

Due to the superior hardness and Young’s modulus, biocompatibility, optical and fluorescence nanodiamond seems to be outstanding among carbon nanomaterials. In this footpath, the development of diamond nanowires (DNWs) is known to be a significantly innovative field due to their diverse applications such as sensors, semiconductors, and electrochemical utilities. Compared to carbon nanotubes, DNWs theoretically have energetic and mechanically viable structures. However, DNW synthesis in a reproducible way is still a challenging task. In fact, most of the DNWs can be successfully synthesized by chemical vapor deposition (CVD) and reactive-ion etching (RIE) techniques. By contrast, solution-based DNW synthesis has also emerged recently. A detailed study on DNW structures may help the emerging researchers to direct toward diverse applications. In this chapter, we comprehensively presented the up-to-date applications of DNWs along with their synthesis, structures and properties

Hybrid Electronic Materials: Characterization and Thin-film Deposition

Hybrid Electronic Materials (HEMs), as defined for this dissertation, are combinations of organic and inorganic materials as may be used to fabricate active device components in “beyond the transistor” electronics. However, the use of organics is often limited by issues such as thermal stability, compatibility with traditional (semiconductor) materials, and current processing technology. Thus, we began our exploration of HEMs with a “new” class of materials called GUMBOS (Group of Uniform Materials Based on Organic Salts) as derived from ionic liquids. For this first segment of our work, we investigated selected species of GUMBOS and nanoGUMBOS via their current-voltage characteristics, electronic sensing capabilities, and amenability to thin-film formation using the technique of electrospraying. For the next segment, and primarily thin-film portion of this research, we elected to include the now more “traditional” material of carbon nanotubes (CNTs). Although reasonably well-characterized, CNTs still offer a significant challenge in terms of thin-film deposition, particularly upon non-conductive substrates. Electrophoretic deposition (EPD) is a solution-based technique that we have previously researched for the deposition of CNT thin-films onto metal and semiconductor substrates. However, EPD is limited by its need for conductive electrodes. We eliminate the latter through an electrospray-assisted form of EPD which accomplishes the two fold task of successfully depositing CNT thin-films onto non-conductive material while increasing the utility of EPD as it applies to HEMs. We also characterized the effect of our electrospray-assisted EPD technique upon CNT film thickness, quality, and morphology. Our investigation concludes with the prototype development of a new method of electrospraying based upon Faraday waves. In conjunction with characterization and thin-film deposition, this prototype demonstrates a means by which to scale HEMs to feasible commercial utilization

Carbon nanotubes on nanoporous alumina: From surface mats to conformal pore filling

Control over nucleation and growth of multi-walled carbon nanotubes in the nanochannels of porous alumina membranes by several combinations of posttreatments, namely exposing the membrane top surface to atmospheric plasma jet and application of standard S1813 photoresist as an additional carbon precursor, is demonstrated. The nanotubes grown after plasma treatment nucleated inside the channels and did not form fibrous mats on the surface. Thus, the nanotube growth mode can be controlled by surface treatment and application of additional precursor, and complex nanotube-based structures can be produced for various applications. A plausible mechanism of nanotube nucleation and growth in the channels is proposed, based on the estimated depth of ion flux penetration into the channels. PACS: 63.22.Np Layered systems; 68. Surfaces and interfaces; Thin films and nanosystems (structure and non-electronic properties); 81.07.-b Nanoscale materials and structures: fabrication and characterization © 2014 Fang et al.; licensee Springer

Graphene for biomedical applications:a review

Since its discovery in 2004, graphene has enticed engineers and researchers from various fields to explore its possibilities to be incepted into various devices and applications. Graphene is deemed a ‘super’ material by researchers due to its extraordinary strength, extremely high surface-to-mass ratio and superconducting properties. Nonetheless, graphene has yet to find plausible footing as an electronics material. In biomedical field, graphene has proved useful in tissue engineering, drug delivery, cancer teraphy, as a component in power unit for biomedical implants and devices and as a vital component in biosensors. Graphene is used as scaffolding for tissue regeneration in stem cell tissue engineering, as active electrodes in supercapacitor for powering wearable and implantable biomedical devices and as detectors in biosensors. In tissue engineering, the extreme strength of monolayer graphene enables it to hold stem cell tissues as scaffold during in-vitro cell regeneration process. In MEMS supercapacitor, graphene’s extremely high surface-to-mass ratio enables it to be used as electrodes in order to increase the power unit’s energy and power densities. A small yet having high energy and power densities cell is needed to power often space constrainted biomedical devices. In FET biosensors, graphene acts as detector electrodes, owing to its superconductivity property. Graphene detector electrodes is capable of detecting target molecules at a concentration level as low as 1 pM, making it the most sensitive biosensor available today. Graphene continues to envisage unique and exciting applications for biomedical field, prompting continuous research which results and implementation could benefit the general public in decades to come

Thermal conductivity measurement of thin film of carbon SWNT using the 3w technique.

We have measured the temperature-dependent thermal conductivity, K(T) of single walled carbon nanotubes from 300 K to 8 K by 3w methods. K(T) exhibits linear temperature dependence in the entire temperature range. Our results are in good agreement with the results obtained by Hone et al. using a standard steady state technique. Also we measured the temperature-dependent thermal conductivity K(T) of quartz and SiO2 in the same temperature range (300 K to 8 K) as a standardization tool. Our technique shows promise for the thermal conductivity measurements of many nanostructures with slight modifications

Characterization and synthesis of nanoscale materials

This dissertation focuses on the systematic study of techniques for characterization and synthesis of nanoscale materials. We have achieved several goals. Firstly, high number density uniform zinc oxide nanostructure growth has been achieved using thermal evaporation, through control of experimental parameters that include source material temperature, substrate temperature, substrate material, gas flow rate, and choice of catalyst. Aligned zinc oxide nanowires, randomly oriented zinc oxide nanowires, zinc oxide container-shaped structures, and zinc oxide nanobelts have been synthesized with high yield. Secondly, using a one parameter family of lattice fringe geometry curves, we show how to examine the epitaxial relationship between catalyst particles and a cylindrical support. Using digital darkfield techniques, this investigation can be automated. Thirdly, the structure relationship between catalyst particles and zinc oxide nanowires has been investigated using scanning and high resolution scanning transmission electron microscopes. A vapor-solid-solid growth model involving a hexagonal array of aligned growth regions is proposed in zinc oxide nanowire formation. Evidence indicates in particular that gold catalyst particles remain solid during ZnO nanowire growth. Finally, the effect of tin catalyst thickness on nanostructure formation has been investigated. The catalyst abundance on the substrate has a direct impact on its ability to absorb ZnO. The thicker coated substrates can absorb more source vapor, and form larger structures, than can thinner coated substrates --Abstract, page iv