Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/20902
Title: CONTROLLABILITY OF ELECTROSPINNING AND ELECTROSPRAYING - ADVANCES AND APPLICATION
Authors: SEBASTIAN HEINZ GERHARD NEUBERT
Keywords: electrospinning, electrospraying, controllability, tissue engineering, catalyst, nanoparticles
Issue Date: 9-Jul-2010
Source: SEBASTIAN HEINZ GERHARD NEUBERT (2010-07-09). CONTROLLABILITY OF ELECTROSPINNING AND ELECTROSPRAYING - ADVANCES AND APPLICATION. ScholarBank@NUS Repository.
Abstract: In this thesis, methods to control electrospinning and electrospraying are presented. Controllability of these processes is defined as the possibility of fibers deposition at a small spot as well as the capability to pattern fibers patterns. Electrospinning of various polymers is focused by modifying the electric field with electrostatic lens systems consisting of additional ring, guard and tube electrodes to enhance the precision of electrospinning. Fibers deposition spot size with a diameter 3-4 mm are achieved. On moving collectors, fibers lines with a width of 0.15 ± 0.013 mm are fabricated. Additional electrodes are also found to be useful to control the pore size of electrospun fibers membranes. To control the polymer electrospinning jet for patterning, switchable steering electrodes are introduced into the standard electrospinning setup. They are charged at a defined frequency with high voltage. Due to the switchable charging of the steering electrodes, the electrospinning polymer jet is set into a state of controllable oscillation. Control over the movement of the polymer jet in one direction is gained with one pair of steering electrodes. In one dimension, the polymer jet is controlled at the maximum over a width of ~33 mm. Two dimensional control is achieved with two pairs of steering electrodes acting perpendicular to each other. Square patterns with a size ~13 mm were achieved. The impact of the process parameters like frequency of the voltage signal, the voltage applied at the steering electrodes or by the geometric dimensions of the steering electrodes on the geometric dimensions of the patterns is shown. With defined fibers orientation, the mechanical properties are made more controllable with this method. With the help of the steering electrodes, not only the fibers structure could be determined and modified, but also the fibers morphology. A buckling fibers morphology is observed for electrospinning. The combination of buckling structure and fibers patterns improves the elasticity of the fibrous membrane from an E-modulus ~19 MPa for random fibers structure to ~2 MPa for patterns fibers with buckling morphology and does not affect the tensile strength. The E-modulus is further reduced to ~1 MPa by exposure to cell culture medium in order to model the cell culturing conditions for the fibrous membranes. The mechanical properties are discussed for application in cardiac tissue engineering. Electrospraying deposition is controlled by attracting the dispersed droplets on a nanostructured conductive collector. Controllability of droplet deposition at nanoscale is shown for electrospraying. The resulting composite structure is evaluated for photocatalytic application. Controlled electrospraying is used for coating a porous fibrous membrane with photocatalytic TiO2 nanoparticles. Besides the investigation of the fabrication mechanism, the mechanical stability and the photocatalytic activity are studied. This membrane combines the function of detoxification as well as filtration and therefore contributes to the protection of human health. The developed methods to enhance controllability of electrospinning and electrospraying are tested for applications to protect and recover human health. The electrospun patterned fibers structures with buckling morphology are investigated to evaluate their potential for application as cardiac tissue engineering patch scaffold to recover myocardial infarction. Besides the structural, morphological and mechanical characterization, the biocompatibility of the membranes was tested with cardiomyocytes.
URI: http://scholarbank.nus.edu.sg/handle/10635/20902
Appears in Collections:Master's Theses (Open)

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