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Dive into the research topics where Sam Liao is active.

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Featured researches published by Sam Liao.


Biointerphases | 2015

Improved fabrication of melt electrospun tissue engineering scaffolds using direct writing and advanced electric field control

Nikola Ristovski; Nathalie Bock; Sam Liao; Sean K. Powell; Jiongyu Ren; Giles T. S. Kirby; Keith A. Blackwood; Maria A. Woodruff

Direct writing melt electrospinning is an additive manufacturing technique capable of the layer-by-layer fabrication of highly ordered 3d tissue engineering scaffolds from micron-diameter fibers. The utility of these scaffolds, however, is limited by the maximum achievable height of controlled fiber deposition, beyond which the structure becomes increasingly disordered. A source of this disorder is charge build-up on the deposited polymer producing unwanted coulombic forces. In this study, the authors introduce a novel melt electrospinning platform with dual voltage power supplies to reduce undesirable charge effects and improve fiber deposition control. The authors produced and characterized several 90° cross-hatched fiber scaffolds using a range of needle/collector plate voltages. Fiber thickness was found to be sensitive only to overall potential and invariant to specific tip/collector voltage. The authors also produced ordered scaffolds up to 200 layers thick (fiber spacing 1 mm and diameter 40 μm) and characterized structure in terms of three distinct zones: ordered, semiordered, and disordered. Our in vitro analysis indicates successful cell attachment and distribution throughout the scaffolds, with little evidence of cell death after seven days. This study demonstrates the importance of electrostatic control for reducing destabilizing polymer charge effects and enabling the fabrication of morphologically suitable scaffolds for tissue engineering.


Archive | 2015

Improving Electrospun Fibre Stacking with Direct Writing for Developing Scaffolds for Tissue Engineering for Non-load Bearing Bone

Keith A. Blackwood; Nikola Ristovski; Sam Liao; Nathalie Bock; Jiongyu Ren; Giles T. S. Kirby; Molly M. Stevens; Roland Steck; Maria A. Woodruff

Melt electrospinning can be used to produce fibres within the micro to nano scale with a deposition in a manner in-line with conventional 3D printing technology’s [1]. Technical issues such as charge build up in subsequent layers lead to limitations in the precision of fibre deposition as the number of layers increases.


Journal of Biomechanics | 2018

Ventricular flow dynamics with varying LVAD inflow cannula lengths: In-silico evaluation in a multiscale model

Sam Liao; Michael Neidlin; Zhi-Yong Li; Benjamin Simpson; Shaun D. Gregory

Left ventricular assist devices are associated with thromboembolic events, which are potentially caused by altered intraventricular flow. Due to patient variability, differences in apical wall thickness affects cannula insertion lengths, potentially promoting unfavourable intraventricular flow patterns which are thought to be correlated to the risk of thrombosis. This study aimed to present a 3D multiscale computational fluid dynamic model of the left ventricle (LV) developed using a commercial software, Ansys, and evaluate the risk of thrombosis with varying inflow cannula insertion lengths in a severely dilated LV. Based on a HeartWare HVAD inflow cannula, insertion lengths of 5, 19, 24 and 50 mm represented cases of apical hypertrophy, typical ranges of apical thicknesses and an experimental length, respectively. The risk of thrombosis was evaluated based on blood washout, residence time, instantaneous blood stagnation and a pulsatility index. By introducing fresh blood to displace pre-existing blood in the LV, after 5 cardiac cycles, 46.7%, 45.7%, 45.1% and 41.8% of pre-existing blood remained for insertion lengths of 5, 19, 24 and 50 mm, respectively. Compared to the 50 mm insertion, blood residence time was at least 9%, 7% and 6% higher with the 5, 19 and 24 mm insertion lengths, respectively. No instantaneous stagnation at the apex was observed directly after the E-wave. Pulsatility indices adjacent to the cannula increased with shorter insertion lengths. For the specific scenario studied, a longer insertion length, relative to LV size, may be advantageous to minimise thrombosis by increasing LV washout and reducing blood residence time.


BioNanoMaterials | 2016

Effect of humidity on melt electrospun polycaprolactone scaffolds

Sam Liao; Brendan Langfield; Nikola Ristovski; Christina Theodoropoulos; Jake Hardt; Keith A. Blackwood; Soniya D. Yambem; Shaun D. Gregory; Maria A. Woodruff; Sean K. Powell

Abstract Direct write melt electrospinning is an additive manufacturing technique used to produce 3D polymer scaffolds for tissue engineering applications. It is similar to conventional 3D printing by layering 2D patterns to build up an object, but uses a high-electric potential to draw out fibres into micron-scale diameters with great precision. Direct write melt electrospinning is related to a well-established fabrication technique, solution electrospinning, but extrudes a melted polymer in a controlled manner rather than a polymer solution. The effect of environmental conditions such as humidity has been extensively studied in the context of solution electrospinning; however, there is a lack of similar studies for direct write melt electrospinning. In this study, melt electrospun polycaprolactone scaffolds were produced with 90 degree cross-hatch architecture at three specific humidity [H2O/air (g/kg)] levels, low (0.74 g/kg), standard (8.94 g/kg), and elevated (11.26 g/kg). Micro-computed tomography and scanning electron microscopic analysis was performed on the scaffolds to investigate the degree to which humidity affects inter-layer ordering, fibre diameter consistency, and fibre surface morphology. Results indicated that humidity does not play a significant role in affecting these scaffold parameters during fabrication within the levels investigated.


Artificial Organs | 2018

Melt Electrospun Bilayered Scaffolds for Tissue Integration of a Suture-Less Inflow Cannula for Rotary Blood Pumps: TISSUE INTEGRATION OF A SUTURE-LESS INFLOW CANNULA

Sam Liao; Christina Theodoropoulos; Keith A. Blackwood; Maria A. Woodruff; Shaun D. Gregory

Implantation of left ventricular assist devices typically requires cardiopulmonary bypass support, which is associated with postoperative complications. A novel suture-less inflow cannula, which can be implanted without bypass, uses mild myocardial compression to seal the interface, however, this may lead to necrosis of the myocardium. To circumvent this issue, a bilayered scaffold has been developed to promote tissue growth at the interface between cannula and myocardium. The bilayered scaffold consists of a silicone base layer, which mimics the seal, and a melt electrospun polycaprolactone scaffold to serve as a tissue integration layer. Biocompatibility of the bilayered scaffolds was assessed by analyzing cell viability, morphology, and metabolic activity of human foreskin fibroblasts cultured on the scaffolds for up to 14 days. There was no evidence of cytotoxicity and the cells adhered readily to the bilayered scaffolds, revealing a cell morphology characteristic of fibroblasts, in contrast to the low cell adhesion observed on flat silicone sheets. The rate of cell proliferation on the bilayered scaffolds rose over the 14-day period and was significantly greater than cells seeded on the silicone sheets. This study suggests that melt electrospun bilayered scaffolds have the potential to support tissue integration of a suture-less inflow cannula for cardiovascular applications. Furthermore, the method of fabrication described here and the application of bilayered scaffolds could also have potential uses in a diverse range of biomedical applications.


Biomedical Engineering Online | 2016

Numerical prediction of thrombus risk in an anatomically dilated left ventricle: the effect of inflow cannula designs

Sam Liao; Benjamin Simpson; Michael Neidlin; Tim A.S. Kaufmann; Zhi-Yong Li; Maria A. Woodruff; Shaun D. Gregory


Institute of Health and Biomedical Innovation; Science & Engineering Faculty | 2014

Characterisation of the micro-architecture of direct writing melt electrospun tissue engineering scaffolds using diffusion tensor and computed tomography microimaging

Sean K. Powell; Nikola Ristovski; Sam Liao; Keith A. Blackwood; Maria A. Woodruff; Konstantin I. Momot


School of Chemistry, Physics & Mechanical Engineering; Institute of Health and Biomedical Innovation; Science & Engineering Faculty | 2018

Melt electrospun bilayered scaffolds for tissue integration of a suture-less inflow cannula for rotary blood pumps

Sam Liao; Christina Theodoropoulos; Keith A. Blackwood; Maria A. Woodruff; Shaun D. Gregory


Artificial Organs | 2018

The Influence of Rotary Blood Pump Speed Modulation on the Risk of Intraventricular Thrombosis: EFFECTS OF LVAD SPEED MODULATION ON INTRAVENTRICULAR FLOW

Sam Liao; Eric L. Wu; Michael Neidlin; Zhi-Yong Li; Benjamin Simpson; Shaun D. Gregory


School of Chemistry, Physics & Mechanical Engineering; Institute of Health and Biomedical Innovation; Science & Engineering Faculty | 2017

3D printing complex chocolate objects: Platform design, optimization and evaluation

Matthew Lanaro; David P. Forrestal; Stefan Scheurer; Damien J. Slinger; Sam Liao; Sean K. Powell; Maria A. Woodruff

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Maria A. Woodruff

Queensland University of Technology

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Keith A. Blackwood

Queensland University of Technology

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Nikola Ristovski

Queensland University of Technology

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Sean K. Powell

Queensland University of Technology

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Christina Theodoropoulos

Queensland University of Technology

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Giles T. S. Kirby

University of South Australia

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