VAPOR GROWN CARBON FIBERS FOR BIOMEDICAL APPLICATIONS

气相生长的碳纤维结合了高密度碳纤维的理想特性 导热和导电性，高强度重量比，非 灾难性的破坏模式，高模数，显著的各向异性和化学 抵抗。它们是一种相对较新的石墨纤维，可以保持 在增强复合材料中的应用前景广阔 假体装置和作为监测细胞过程的微电极。 电子传导的固有各向异性表明它们 在神经科学中的应用。 这项研究的目标是量身定做或“微调”电气和 导热系数、抗拉强度、弹性模数和表面 通过各种掺杂、涂层和退火程序获得性能 考虑到它们在假体和作为微电极和 适合生物的电信号传输和神经模型。我们 将尝试完善气相生长纤维的环形结构，以提供 一种“闭合”，即缺少活动的曲面边。“关闭”是必要的 在人体内需要化学惰性的那些应用。这 是由石墨的001晶面的低反应性提供的。这 “闭合”还可以通过呈现一种非常 低反应边表面积。我们建议通过等离子体对纤维进行涂层。 用金刚石沉积以降低孔隙率和增加物理性能 纤维的强度。或者，表面粗糙度将为 当生长到肌腱和肌肉纤维时被合并到纤维中 想要。这一过程将通过受控氧化进行。 通过使用固态ESR测量，在我们新的指导下 开发的理论处理，我们将表征气相生长的碳 生物用纤维。的极其重要的性质 电子迁移率，电导率各向异性，微晶尺寸，程度 基面有序度和电子扩散常数将从 电子自旋共振吸收线型分析。电子显微镜将揭示 由于生长条件的变化而进行的结构调整 伴随着热退火。用来测量总表面积 氪和有氧的活性表面积将被执行。氧 表面浓度将通过监测OLS和CLS XPS来确定 强度。表面有序将用低能电子探测 绕射。这些纤维作为微电极的用途将是 与格雷格·斯温博士在该中心合作研究 堪萨斯大学的生物分析研究。 气相生长纤维的所有上述性质取决于 对它们的热和化学制备方法进行了批判。新的 将采用生长方法来提高纤维的性能 有用处。因此，我们将确定最佳的制备方法和 将导致用于假体的先进材料的工艺条件， 神经和生化用途。

Vapor-grown carbon fibers combine the desirable characteristics of high thermal and electrical conductivity, high strength to weight ratio, non- catastrophic failure modes, high modulus, marked anisotropy and chemical resistance. They are a relatively new form of graphite fiber which hold great promise for application in reinforced composite materials for prosthetic devices and as microelectrodes for monitoring cell processes. The inherent anisotropy of the electronic conduction suggests their application in the neural sciences. The goal of this research is to tailor or "fine-tune" the electrical and thermal conductivity, the tensile strength and the modulus and the surface properties through various doping, coating and annealing procedures to allow for their application in prosthesis and as microelectrodes and biologically-suited electrical signal transmission and nerve models. We will attempt to perfect the annular structure of vapor-grown fibers to give a "closure", the lack of active surface edges. "Closure" is necessary for those applications in the human body that require chemical inertness. This is provided by the low reactivity of the 001 planes of graphite. This "closure" also enhances the resistance to oxidation by presenting a very low reactive-edge surface area. We propose to coat fibers via plasma deposition with diamond to lower porosity and increase the physical strength of the fibers. Alternatively, surface roughness will be incorporated into the fibers when growth into tendons and muscle fibers is desired. This process will be carried out through controlled oxidation. Through the use of solid-state ESR measurements, guided by our newly developed theoretical treatment, we will characterize vapor-grown carbon fibers for biological applications. The extremely important properties of electron mobility, conductivity anisotropy, crystallite size, degree of basal plane ordering,a nd electron diffusion constant will be inferred from analysis of ESR absorption lineshapes. Electron microscopy will reveal structural modifications due to changes in growth conditions and those accompanying thermal annealing. Measurement of total surface area with krypton and active surface area with oxygen will be performed. Oxygen surface concentration will be determined by monitoring the Ols and Cls XPS intensities. Surface order will be probed with low-energy electron diffraction. The utility of these fibers as microelectrodes will be studied in collaboration with Dr. Greg Swain at the Center for Bioanalytical Research at the University of Kansas. All of the above-mentioned properties of vapor-grown fibers depend critically upon the method of their thermal and chemical preparation. New growth methods will be employed in an effort to enhance the fibers' usefulness. We will, thus, determine the optimal preparation and processing conditions which will lead to advanced materials for prothesis, neural and biochemical use.