Browsing by Subject "Polymer fiber drawing"

Now showing 1 - 2 of 2

Open Access
High performance multimaterial fibers and devices
(2016-06) Say, Mehmet Girayhan
Fabricating low energy requiring and self-powered flexible electronic devices can decrease world energy need since energy demand seems to be one of the most fundamental problems in the near future. An excellent solution to overcome this drawback is fabricating functional and energy efficient materials. Fabricating high piezoelectric coefficient materials that are compatible with mass production, easy to produce, low cost and non-toxic is highly demanded in order to design highly sensitive sensors and self-powered devices. This thesis introduces piezoelectric polymer (PVDF-TrFE) based several sensor types, energy harvesting devices such as; prosthetic hand, cardiac sensors, electronic skin, which represent promising device architectures for flexible electronics. Semiconductor, metal, composite, piezoelectric materials or polymers can be drawn by thermal fiber drawing and by applying iterative size reduction technique, the geometry, size and length of fabricated structures can be controlled, which also enables us to design novel in fiber, fiber-array devices at nanoscale. First, to enhance PVDF-TrFE fiber performance, crystallinity of fibers was improved by introducing new designs and phase transition mechanism was investigated in fabricated films and fibers. Finally, conductive composite material for flexible interconnects and electrodes was developed. As a whole, a variety of novel piezoelectric and conductive composite fibers were fabricated by using novel size reduction technique and fiber devices were designed for flexible electronics applications.
Open Access
Micro and nanotextured polymer fibers for open microfluidics
(2016-01) Yunusa, Muhammad
Microfluidics is the science of controlling low volumes of fluids in a microchannel. It is used in diverse area of applications such as chemical and biological analysis. Benefits of microfluidics are fast analysis, short reaction times, and portability of device. Current fabrication techniques of lab-on-a-chip microfluidic devices are soft lithography and micromachining. However, these methods suffer from design limitations such as flexibility of product, high cost, integration of external components, and biocompatibility. Surface textured polymer fibers are utilized as a novel platform for the fabrication of affordable microfluidic devices. Fibers are produced by thermal drawing technique tens of meters-long at a time and comprise twenty continuous and ordered V-grooves channels on their surfaces. Extreme anisotropic wetting behavior due to capillary action along the grooves of fibers is observed after surface modifications with polydopamine (PDA) coating and Ultraviolet/Ozone (UV/O) treatment. Three-dimensional arrays of flexible fibers spontaneously spread liquid on predefined paths without the need of external pumps or actuators. In addition, surface modification with organically modified silica nanoparticles was added on top of the V-grooves to enhance the hydrophobicity of the fiber surfaces. Surface textured fibers are well suited for the fabrication of flexible, robust, lightweight and affordable microfluidic devices which is believed to expand the role of microfluidics in a scope of fields including drug discovery, medical diagnostics and monitoring food and water quality.