Engineering Commons^™

Material Properties And Microstructural Characterization Of Specimens, T.J. Silverman, Allison Kinney, B. South, W. Yong, J.H. Koo

Allison Kinney

The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new software. This paper quantifies differences in mechanical and morphological properties of specimens built first using a Vanguard HS (high-speed) system and again using the same system with the HiQ upgrade applied. Standard specimens are built from DuraForm PA material and tested for tensile modulus, tensile strength, elongation at break, flexural modulus and Izod impact strength. The design of the specimen battery, the conduction of the tests and the significance of the results are discussed. The upgrade is found to …

The Influence Of Optimality Criteria On Optimization Predictions Of Muscle And Knee Contact Forces During Walking, Allison Kinney

Allison Kinney

Funded research sponsored by the University of Dayton Research Council Seed Award. Awarded $6,500.

Support For New Course Development For Introduction To Biomechanics, Allison Kinney

Allison Kinney

Funded research sponsored by the University of Dayton KEEN Fellows Cohort. Awarded $13,000.

Three-Dimensional Vibrometry Of The Human Eardrum With Stroboscopic Lensless Digital Holography, Morteza Khaleghi, Cosme Furlong, Mike Ravicz, Jeffrey T. Cheng, John J. Rosowski

Morteza Khaleghi

The eardrum or tympanic membrane (TM) transforms acoustic energy at the ear canal into mechanical motions of the ossicles. The acousto-mechanical transformer behavior of the TM is determined by its shape, three-dimensional (3-D) motion, and mechanical properties. We have developed an optoelectronic holographic system to measure the shape and 3-D sound-induced displacements of the TM. The shape of the TM is measured with dual-wavelength holographic contouring using a tunable near IR laser source with a central wavelength of 780 nm. 3-D components of sound-induced displacements of the TM are measured with the method of multiple sensitivity vectors using stroboscopic holographic …

How Has The Knee Grand Challenge Improved Musculoskeletal Modeling Research?, Benjamin Fregly, Allison Kinney, Thor Besier, Darryl D'Lima

Allison Kinney

No abstract provided.

Feasibility Tuning To Improve Optimization Prediction Of Knee Contact Forces, Allison Kinney, Anil Rao, Benjamin Fregly

Allison Kinney

No abstract provided.

Predicting Unmeasured Muscle Excitations From Measured Muscle Synergies, Allison Kinney, N. Bianco, Benjamin Fregly

Allison Kinney

No abstract provided.

Full-Field Vibrometry By High-Speed Digital Holography For Middle-Ear Mechanics, Ivo Dobrev

Ivo Dobrev

Hearing loss affects approximately 1 in 10 people in the world and this percentage is increasing every year. Some of the most common courses for hearing loss are disorders of the human tympanic membrane (TM or eardrum) and middle-ear. Early detection and diagnosis of hearing loss as well as research and understanding of the hearing process depend on medical and research tools for quantification of the hearing capabilities, including the function of the human TM in the complex acoustic-mechanical transformation of environmental sounds into vibrations of the middle- and the inner-ear.

Current ear exams are assessing the state of the …

Measuring The Mechanical Properties Of Living Cells Using Atomic Force Microscopy, Nancy Burnham, Gawain Thomas, Terri Camesano, Qi Wen

Nancy A. Burnham

Mechanical properties of cells and extracellular matrix (ECM) play important roles in many biological processes including stem cell differentiation, tumor formation, and wound healing. Changes in stiffness of cells and ECM are often signs of changes in cell physiology or diseases in tissues. Hence, cell stiffness is an index to evaluate the status of cell cultures. Among the multitude of methods applied to measure the stiffness of cells and tissues, micro-indentation using an Atomic Force Microscope (AFM) provides a way to reliably measure the stiffness of living cells. This method has been widely applied to characterize the micro-scale stiffness for …

Pre-Swing Deficits In Forward Propulsion, Swing Initiation And Power Generation By Individual Muscles During Hemiparetic Walking, Carrie Peterson, Allison Kinney, Stephen Kautz, Richard Neptune

Allison Kinney

No abstract provided.

Neural Vs. Statistical Classifier In Conjunction With Genetic Algorithm Based Feature Selection, Ping Zhang, Brijesh Verma, Kuldeep Kumar

Kuldeep Kumar

Digital mammography is one of the most suitable methods for early detection of breast cancer. It uses digital mammograms to find suspicious areas containing benign and malignant microcalcifications. However, it is very difficult to distinguish benign and malignant microcalcifications. This is reflected in the high percentage of unnecessary biopsies that are performed and many deaths caused by late detection or misdiagnosis. A computer based feature selection and classification system can provide a second opinion to the radiologists in assessment of microcalcifications. The research in this paper proposes and investigates a neural-genetic algorithm for feature selection in conjunction with neural and …

A Hybrid Classifier For Mass Classification With Different Kinds Of Features In Mammography, Ping Zhang, Kuldeep Kumar, Brijesh Verma

Kuldeep Kumar

This paper proposes a hybrid system which combines computer extracted features and human interpreted features from the mammogram, with the statistical classifier’s output as another kind of feature in conjunction with a genetic neural network classifier. The hybrid system produced better results than the single statistical classifier and neural network. The highest classification rate reached 91.3%. The area value under the ROC curve is 0.962. The results indicated that the mixed features contribute greatly for the classification of mass patterns into benign and malignant.

Human Microvasculature Fabrication Using Thermal Inkjet Printing Technology, Xiaofeng Cui, Thomas Boland

Thomas Boland

The current tissue engineering paradigm is that successfully engineered thick tissues must include vasculature. As biological approaches alone, such as VEGF, have fallen short of their promises, one may look for an engineering approach to build microvasculature. Layer-by-layer approaches for customized fabrication of cell/scaffold constructs have shown some potential in building complex 3D structures. With the advent of cell printing, one may be able to build precise human microvasculature with suitable bio-ink. Human microvascular endothelial cells (HMVEC) and fibrin were studied as bio-ink for microvasculature construction. Endothelial cells are the only cells to compose the human capillaries and also form …

Electrophysiological Characterization Of Embryonic Hippocampal Neurons Cultured In A 3d Collagen Hydrogel, Tao Xu, Peter Molnar, Gregory Cassie, Mainak Das, Thomas Boland, Jay Hickman

Thomas Boland

Rat embryonic hippocampal neurons were cultured in (1) 3D collagen hydrogels as 'entrapped' evenly distributed cells, (2) at the interface of two collagen layers (sandwich model), and (3) on the surface of collagen coated coverslips (2D model). In the 'entrapment' model the neuronal processes grew out of the plane of the cell body and extended into the collagen matrix, in contrast to the sandwich model where the cells and their processes rarely left the plane in which they were seeded. Hippocampal neurons 'entrapped' in the 3D collagen gel grew the same number, but shorter, processes and exhibited improved survival compared …

Fabrication And Characterization Of Bio-Engineered Cardiac Pseudo Tissues, Tao Xu, Catalin Baicu, Michael Aho, Michael Zile, Thomas Boland

Thomas Boland

We report to fabricate functional three-dimensional (3D) tissue constructs by using an inkjet based bio-prototyping method. With the use of the modified inkjet printers, contractile cardiac hybrids that exhibit the forms of the 3D rectangular sheet and even the ‘half heart’ (with two connected ventricles) have been fabricated by arranging alternate layers of biocompatible alginate hydrogels and mammalian cardiac cells according to pre-designed 3D patterns. In this study, primary feline adult and H1 cardiomyocytes were used as model cardiac cells. Alginate hydrogels with controlled micro-shell structures were built by spraying cross-linkers in micro-drops onto un-gelled alginic acid. The cells remained …

Synthesis And Characterization Of Biodegradable Elastomeric Polyurethane Scaffolds Fabricated By The Inkjet Technique.”, Changhong Zhang, Xuejun Wen, Narendra Vyavahare, Thomas Boland

Thomas Boland

Biodegradable polyurethanes (PUs) were synthesized from methylene di-p-phenyl-diisocyanate (MDI), polycaprolactone diol (PCL-diol) and N,N-bis (2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES), serving as a hard segment, soft segment and chain extender, respectively. MDI was chosen due to its reactivity and wide application in synthesis of biomedical polyurethanes due to its reactivity; PCL-diol was chosen because of its biodegradability; and BES was chosen because it allowed the introduction sulfonic acid groups onto the polymer chains. We evaluated the polyurethanes' degradation rate, mechanical properties, hydrophilicity, antithrombogenecity, and ability to support fibroblast cell attachment and growth by comparing with polymers having a 2,2-(methylimino)diethanol (MIDE) chain extender. Mechanical …

Loading Dependent Swelling And Release Properties Of Novel Biodegradable, Elastic And Environmental Stimuli-Sensitive Polyurethanes, Changhong Zhang, Kejia Zhao, Tj Hu, Xiaofeng Cui, Nathan Brown, Thomas Boland

Thomas Boland

A novel degradable, elastic, anionic, and linear polyurethane was synthesized from hexamethylene diisocyanate, polycaprolactone diol, and a bicine chain extender. The chemical structure, mechanical properties, degradation rate, and swelling ratio were characterized by comparing the polymer with a polyurethane containing a 2,2-(methylimino) diethanol chain extender. Due to the incorporation of negatively charged carboxyl side groups, the bicine extended polymers exhibited higher micro-phase separation, better mechanical properties in dry condition, and better sensitivity to environmental stimuli than controls, as demonstrated by its high swelling ratio at elevated pH, lower ionic strength, or higher temperature. The swelling ratio of membranes showed reversible …

Plantar Flexor Muscle Force Substitution During Walking With A Unilateral Passive Dynamic Ankle-Foot Orthosis: A Simulation Study, Allison Kinney, Richard Neptune, S. Stanhope

Allison Kinney

No abstract provided.

Application Of Inkjet Printing To Tissue Engineering, Thomas Boland, Tao Xu, Brook Damon, Xiaofeng Cui

Thomas Boland

ecent advances in organ printing technology for applications relating to medical interventions and organ replacement are described. Organ printing refers to the placement of various cell types into a soft scaffold fabricated according to a computer-aided design template using a single device. Computer aided scaffold topology design has recently gained attention as a viable option to achieve function and mass transport requirements within tissue engineering scaffolds. An exciting advance pioneered in our laboratory is that of simultaneous printing of cells and biomaterials, which allows precise placement of cells and proteins within 3-D hydrogel structures. This advance raises the possibility of …

The Use Of Extracellular Matrix As An Inductive Scaffold For The Partial Replacement Of Functional Myocardium., Glenn Gaudette, S Badylak, P Kochupura, I Cohen, S Doronin, A Saltman, T Gilbert, D Kelly, R Ignotz

Glenn R. Gaudette

Regenerative medicine approaches for the treatment of damaged or missing myocardial tissue include cell-based therapies, scaffold-based therapies, and/or the use of specific growth factors and cytokines. The present study evaluated the ability of extracellular matrix (ECM) derived from porcine urinary bladder to serve as an inductive scaffold for myocardial repair. ECM scaffolds have been shown to support constructive remodeling of other tissue types including the lower urinary tract, the dermis, the esophagus, and dura mater by mechanisms that include the recruitment of bone marrow-derived progenitor cells, angiogenesis, and the generation of bioactive molecules that result from degradation of the ECM. …

Viability And Electrophysiology Of Neural Cell Structures Generated By The Inkjet Printing Method, Tao Xu, Cassie Gregory, Peter Molnar, S Jalota, Sarit Bhaduri, Thomas Boland

Thomas Boland

Complex cellular patterns and structures were created by automated and direct inkjet printing of primary embryonic hippocampal and cortical neurons. Immunostaining analysis and whole-cell patch-clamp recordings showed that embryonic hippocampal and cortical neurons maintained basic cellular properties and functions, including normal, healthy neuronal phenotypes and electrophysiological characteristics, after being printed through thermal inkjet nozzles. In addition, in this study a new method was developed to create 3D cellular structures: sheets of neural cells were layered on each other (layer-by-layer process) by alternate inkjet printing of NT2 cells and fibrin gels. These results and findings, taken together, show that inkjet printing …

Inkjet Printing Of Viable Mammalian Cells, Tao Xu, Joyce Jin, Cassie Gregory, Jay Hickman, Thomas Boland

Thomas Boland

The purpose of this study was to explore the use of a commercial thermal printer to deposit Chinese Hamster Ovary (CHO) and embryonic motoneuron cells into pre-defined patterns. These experiments were undertaken to verify the biocompatibility of thermal inkjet printing of mammalian cells and the ability to assemble them into viable constructs. Using a modified Hewlett Packard (HP) 550C computer printer and an HP 51626a ink cartridge, CHO cells and rat embryonic motoneurons were suspended separately in a concentrated phosphate buffered saline solution (3 x). The cells were subsequently printed as a kind of "ink" onto several "bio-papers" made from …

Advances In Tissue Engineering: Cell Printing, David Varghese, Malay Deshpande, Priya Kesari, S Ohri, Thomas Boland

Thomas Boland

No abstract provided.

Development And Analysis Of A Software Package To Quantify In Vivo Polyethylene Wear After Total Hip Arthroplasty, Allison Kinney, Catherine Ambrose

Allison Kinney

Since the first total hip arthroplasty (THA) in 1938, THA evolved and developed into one of the major concentrations of orthopaedic research. The typical hip implant device used today incorporates a femoral and an acetabular component that serve to replicate the anatomical and mechanical functions of the natural hip joint. However, several problems exist that can effect the function of the implant device. Wear in the polyethylene liner of the acetabular component of the total hip replacement device is known as one of the major factors that affects the longevity of total hip replacement devices. Both manual and computer-aided techniques …

Inkjet Printing For High Throughput Cell Patterning, Elisabeth Roth, Tao Xu, Mainak Das, Cassie Gregory, Jay Hickman, Thomas Boland

Thomas Boland

The adaptation of inkjet printing technology to the complex fields of tissue engineering and biomaterial development presents the potential to increase progress in these emerging technologies through the implementation of this high-throughput capability via automated processes to enable precise control and repeatability. In this paper, a method of applying high-throughput inkjet printing to control cellular attachment and proliferation by precise, automated deposition of collagen is presented. The results indicate that commercial inkjet printing technology can be used to create viable cellular patterns with a resolution of 350 microm through the deposition of biologically active proteins. This method demonstrates a combination …

Construction Of High- Density Bacterial Colony Arrays And Patterns By The Ink Jet Method, Tao Xu, Sevastioni Petridou, Eric Lee, Elisabeth Roth, Narendra Vyavahare, Jay Hickman, Thomas Boland

Thomas Boland

We have developed a method for fabricating bacterial colony arrays and complex patterns using commercially available ink-jet printers. Bacterial colony arrays with a density of 100 colonies/cm(2) were obtained by directly ejecting Escherichia coli (E. coli) onto agar-coated substrates at a rapid arraying speed of 880 spots per second. Adjusting the concentration of bacterial suspensions allowed single colonies of viable bacteria to be obtained. In addition, complex patterns of viable bacteria as well as bacteria density gradients were constructed using desktop printers controlled by a simple software program.

Tissue-Engineering Constructs, Using Photopolymerizable Hydrogels And Stereolithography.”, Busaina Dhariwala, Elaine Hunt, Thomas Boland

Thomas Boland

One of the most important aspects of tissue engineering is the design of the scaffold providing the mechanical strength and access to nutrients for the new tissue. For customized tissue engineering, it is essential to be able to fabricate three-dimensional scaffolds of various geometric shapes, in order to repair defects caused by accidents, surgery, or birth. Rapid prototyping or solid free-form fabrication (SFF) techniques hold great promise for designing three-dimensional customized scaffolds, yet traditional cell-seeding techniques may not provide enough cell mass for larger constructs. This article presents a novel attempt to fabricate three-dimensional scaffolds, using hydrogels combined with cell …

Cell And Organ Printing 2: Fusion Of Cell Aggregates In Three-Dimensional Gels, Thomas Boland, Vladimir Mironov, Anna Gutowska, Elisabeth Roth, Roger Markwald

Thomas Boland

We recently developed a cell printer (Wilson and Boland, 2003) that enables us to place cells in positions that mimic their respective positions in organs. However, this technology was limited to the printing of two-dimensional (2D) tissue constructs. Here we describe the use of thermosensitive gels to generate sequential layers for cell printing. The ability to drop cells on previously printed successive layers provides a real opportunity for the realization of three-dimensional (3D) organ printing. Organ printing will allow us to print complex 3D organs with computer-controlled, exact placing of different cell types, by a process that can be completed …

Cell And Organ Printing 1: Protein And Cell Printers, Cris Wilson, Thomas Boland

Thomas Boland

We have developed several devices for positioning organic molecules, molecular aggregates, cells, and single-cell organisms onto solid supports. These printers can create stable, functional protein arrays using an inexpensive technology. The cell printer allows us to create cell libraries as well as cellular assemblies that mimic their respective position in organs. The printers are derived from commercially available ink-jet printers that are modified to dispense protein or cell solutions instead of ink. We describe here the modifications to the print heads, and the printer hardware and software that enabled us to adapt the ink-jet printers for the manufacture of cell …

Characterization Of Patterned Self-Assembled Monolayers And Protein Arrays Generated By The Ink-Jet Method, Laura Pardo, Thomas Boland

Thomas Boland

Commercial ink-jet printers were used with little modification to deposit alkanethiols onto gold substrata and several proteins onto silica supports. The resulting patterns of alkanethiols form self-assembled layers comparable to those obtained by microcontact printing or solution adsorption. The method has been used successfully to create binary chemical gradients and patterns of tertiary functionality. The proteins form dense patterns on the substrates and seem to maintain their configuration as measured by their ability to bind their specific ligands. Four different proteins were printed simultaneously, allowing for positive and negative controls. This "drop-on-demand" printing method is an inexpensive, flexible alternative to …