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Low-concentration hydrogels have favorable properties for many cell functions in tissue engineering but are considerably limited from a scaffold fabrication point of view due to poor three-dimensional (3D) printability. Here, we developed an indirect-bioprinting process for alginate scaffolds and characterized the potential of these scaffolds for nerve tissue engineering applications. The indirect-bioprinting process involves (1) printing a sacrificial framework from gelatin, (2) impregnating the framework with low-concentration alginate, and (3) removing the gelatin framework by an incubation process, thus forming low-concentration alginate scaffolds. The scaffolds were characterized by compression testing, swelling, degradation, and morphological and biological assessment of incorporated or seeded Schwann cells. For comparison, varying concentrations of alginate scaffolds (from 0.5% to 3%) were fabricated and sterilized using either ultraviolet light or ethanol. Results indicated that scaffolds can be fabricated using the indirect-bioprinting process, wherein the scaffold properties are affected by the concentration of alginate and sterilization technique used. These factors provide effective means of regulating the properties of scaffolds fabricated using the indirect-bioprinting process. Cell-incorporated scaffolds demonstrated better cell viability than bulk gels. In addition, scaffolds showed better cell functionality when fabricated with a lower concentration of alginate compared to a higher concentration. The indirect-bioprinting process that we implemented could be extended to other types of low-concentration hydrogels to address the tradeoffs between printability and properties for favorable cell functions.

Bone, the main constituent of the skeletal system is a hard tissue that results from the impregnation of a soft organic matrix (35%) (collagen fibers and non-collagenous proteins) by calcium and phosphorous, mainly in form of hydroxyapatite, (Ca10(PO4)6(OH)2), as well as carbonate, citrate, magnesium, fluoride, and strontium (65%) [1]. As calcium deposits, bone serves a critical function acting as a reservoir from which the mineral, vital to many physiologic processes, can readily be obtained. The most remarkable characteristic of bone is its ability to perceive changes in mechanical demands bestowed upon its components and realize the required structural transformation to adapt to new conditions. By way of this complex process of modeling and remodeling, bone cannot only grow stronger and harder but can also modify its form.

Ultrasound is a cost-effective, readily available, and non-ionizing modality for musculoskeletal imaging. Though some research groups have pursued methods that involve submerging the transducer and imaged body segment into a water bath, many limitations remain in regards to acquiring an unloaded volumetric image of an entire human limb in a fast, safe and adequately accurate manner. A 3D dataset of a limb is useful in several rehabilitative applications including biomechanical modeling of soft tissue, prosthetic socket design, monitoring muscle condition and disease progression, bone health, and orthopedic surgery. This paper builds on previous work from our group and presents the design, prototyping, and preliminary testing of a novel multi- modal imaging system for rapidly acquiring volumetric ultrasound imagery of human limbs, with a particular focus on residual limbs for improved prosthesis design. Our system employs a mecha- nized water tank setup to scan a limb with a clinical ultrasound transducer, and 3D optical imagery to track motion during a scan. The iterative closest point algorithm is utilized to compensate for motion and stitch the images into a final dataset. The results show preliminary 2D and 3D imaging of both a tissue-mimicking phantom and residual limbs. A volumetric error compares the ultrasound image data obtained to a previous MRI method. The results indicate potential for future clinical implementation. Con- cepts presented in this work could reasonably transfer to other imaging applications such as acoustic tomography, where motion artifact may distort image reconstruction.

Ceramic composite materials are increasingly used in dental restoration procedures, but current ceramic surface designs do not yet achieve the osseointegration potential of state-of-the-art titanium implants. Rapid bone tissue integration of an implant is greatly dependent on its surface characteristics, but the material properties of ceramic composite materials interfere with classical surface modification techniques. Here, ultra-short pulsed laser machining, which offers a defined energy input mitigating a heat-affected zone, is explored for surface modification of ceramic composites. Inspired by surface textures of clinically relevant titanium implants, dual roughness surfaces are laser patterned. Raman mapping reveals a negligible effect of ultra-short pulsed laser ablation on material properties, but a laser-induced change in the wetting state is revealed by static contact angle measurements. Laser patterning of surfaces also influences blood coagulation, but not the attachment and spreading of osteoblastic cells. The presented laser machining approach thus allows the introduction of a rational surface design on ceramic composites, holding great promise for the manufacturing of ceramic implants., Applied Surface Science, 545, ISSN:0169-4332, ISSN:1873-5584

Hypoxia commonly occurs within tumours and is a major cause of radiotherapy resistance. Clinical outcomes could be improved by locating and selectively increasing the dose delivered to hypoxic regions. Here we describe a miniature implantable sensor for real-time monitoring of tissue oxygenation that could enable this novel treatment approach to be implemented. The sensor uses a solid-state electrochemical cell that was microfabricated at wafer level on a silicon substrate, and includes an integrated reference electrode and electrolyte membrane. It gave a linear response to oxygen concentration, and was unaffected by sterilisation and irradiation, but showed susceptibility to biofouling. Oxygen selectivity was also evaluated against various clinically relevant electroactive compounds. We investigated its robustness and functionality under realistic clinical conditions using a sheep model of lung cancer. The sensor remained functional following CT-guided tumour implantation, and was sufficiently sensitive to track acute changes in oxygenation within tumour tissue.

Finite element (FE) simulations are performed to investigate the effect of fiber induced anisotropy on the notch behavior in hyperelastic skin type materials. The modified anisotropic (MA) model is used to define the constitutive behavior in FE simulations through Abaqus user defined material model UMAT. A parametric study is carried out to examine the effect of fiber orientation, notch root radius and sample geometry on the stress field ahead of the notch tip. A non-dimensional parameter ξ is defined to characterize the combined effect of J energy and average anisotropic energy ϕ a n i s o - avg on the notch behavior. It is shown that fibre orientation significantly influences the stress state and J-integral at the notch. The findings of the present study will be helpful in determining optimal constitution and orientation of skin grafts at locations of high stress and complex geometries, such as corner of eyes and lips, etc.

Computational models provide a powerful tool for pre-clinical assessment of medical devices and early evaluation of potential risks to the patient in terms of plaque fragmentation and in-stent restenosis (ISR). Using a suitable constitutive model for arterial tissue is key for the development of a reliable computational model. Although some inelastic phenomena such as stress softening and permanent deformation likely occur due to the supra-physiological loading of arterial tissue during the stenting procedure, hyperelastic constitutive models have been employed in most of the previously developed computational models. This study presents a finite element model for stent deployment into a patient-specific stenosed artery while inelastic arterial behaviors due to supra-physiological loading of the tissue have been considered. Specifically, the maximum stress in the plaque and the arterial layers which is the main cause of plaque fracture during stent deployment and the surgically-induced injury (damage) in the arterial wall, as the main cause of ISR, are presented. The results are compared with the commonly-used hyperelastic behavior for arterial layers. Furthermore, the effects of arterial material parameter variation, analogues to different patients, are investigated. A higher amount of damage is predicted for the artery which shows a higher stress in a specific strain.

In this article, we try to track the neuroelectrical signal from its retinal inception until it signals the human visual awareness through what we called, neurobiological wires to consciousness. We also provide a fulsome electrophysiological metric, namely, brain energy wishing for better quantification to the human global consciousness. Based on the literature review, this metric is expected to quantify the human global visual awareness, namely because of recent special findings in binocular rivalry phenomenon. The article also offers simple ways to build up binocular rivalry experiments.

Scaffolds and implants used for tissue engineering need to be adapted for their mechanical properties with respect to their environment within the human body. Therefore, a novel composite for skin tissue engineering is presented by use of blends of Poly(vinylpyrrolidone) (PVP) and Poly(glycerol sebacate) (PGS) were fabricated via the needleless electrospinning technique. The formed PGS/PVP blends were morphologically, thermochemically and mechanically characterized. The morphology of the developed fibers related to the concentration of PGS, with high concentrations of PGS merging the fibers together plasticizing the scaffold. The tensile modulus appeared to be affected by the concentration of PGS within the blends, with an apparent decrease in the elastic modulus of the electrospun mats and an exponential increase of the elongation at break. Ultraviolet (UV) crosslinking of PGS/PVP significantly decreased and stabilized the wettability of the formed fiber mats, as indicated by contact angle measurements. In vitro examination showed good viability and proliferation of human dermal fibroblasts over the period of a week. The present findings provide important insights for tuning the elastic properties of electrospun material by incorporating this unique elastomer, as a promising future candidate for skin substitute constructs.

Existing robotic surgical platforms face limitations which include the balance between the scale of the robot and its capability in terms of range of motion, load capacity, and tool manipulation. These limitations can be overcome by taking advantage of fluid power as an enabling technology with its inherent power density and controllability. As a proof-of-concept for this approach, we are pursuing the design of a novel, dexterous robotic surgical tool targeted towards transgastric natural orifice surgery.The design for this hydraulic surgical platform and the corresponding analysis are presented to demonstrate the theoretical system performance in terms of tool positioning and input requirements. The design involves a combination of a novel 3D valve, hydraulic artificial muscles, and multi-segmented flexible manipulator arms that fit in the lumen of an endoscope. A dynamic model of the system is created. Numerical simulations show that a hydraulic endoscopic surgical robot can produce the desired performance without using large external manipulators such as those employed by conventional surgical robots. They also provide insight into the component interactions and input response of the system. Future work will include manufacturing a prototype to validate the concept and the numerical models.

Intended for medical students studying the evaluation and diagnosis of heart arrhythmias, the beating heart arrhythmia simulator combines visual, auditory, and tactile stimuli to enhance the student's retention of the subtle differences between various conditions of the heart necessary for diagnosis. Unlike existing heart arrhythmia simulators, our simulator is low cost and easily deployable in the classroom setting. A design consisting of solenoid actuators, a silicon heart model, and a graphical user interface has been developed and prototyped. Future design development and conceptual validation is necessary prior to deployment.

Three-dimensional (3D) bioplotting has been widely used to print hydrogel scaffolds for tissue engineering applications. One issue involved in 3D bioplotting is to achieve the scaffold structure with the desired mechanical properties. To overcome this issue, various numerical methods have been developed to predict the mechanical properties of scaffolds, but limited by the imperfect representation of one key feature of scaffolds fabricated by 3D bioplotting, i.e., the penetration or fusion of strands in one layer into the previous layer. This paper presents our study on the development of a novel numerical model to predict the elastic modulus (one important index of mechanical properties) of 3D bioplotted scaffolds considering the aforementioned strand penetration. For this, the finite element method was used for the model development, while medium-viscosity alginate was selected for scaffold fabrication by the 3D bioplotting technique. The elastic modulus of the bioplotted scaffolds was characterized using mechanical testing and results were compared with those predicted from the developed model, demonstrating a strong congruity between them. Once validated, the developed model was also used to investigate the effect of other geometrical features on the mechanical behavior of bioplotted scaffolds. Our results show that the penetration, pore size, and number of printed layers have significant effects on the elastic modulus of bioplotted scaffolds, and also suggest that the developed model can be used as a powerful tool to modulate the mechanical behavior of bioplotted scaffolds.

Rigid link robots currently dominate the market for manipulators in assistive technology, though research on continuum robots for assistive technology has been developing over recent years. These types of robots have a continuous backbone that allows them to have infinite degrees of freedom, making them highly compliant, however this brings challenges in terms of modelling and control. Additionally, materials for this type of application require specific qualities. In this work, we attempt to address these problems while designing a continuum arm suitable for assistive technology applications. Bendy ARM 2.0 is a revised version of the first Bendy ARM robot to accomplish these goals. In its first iteration, Bendy ARM had limitations in its mechanical function, such as the structural performance of the backbone, which decreased the accuracy in positional control. Nitinol was tested as a new backbone material but failed during testing so a low density polyethylene was chosen. Cable conduits were added to help reduce the mechanical coupling between the proximal and distal segments of the manipulator. Motion processing units (MPU) are utilized to gather tilt angles and provide direction for automated movements. Due to the arms natural rotation, this data alone was not enough to consistently control and place the robot. With the information gathered, further consideration of backbone material and usage of MPU data is required for an automatable robot.

A novel approach for machining of cylindrical hard materials and arbitrary shapes is presented. Alumina-toughened zirconia dental implants with complex geometry are manufactured with femtosecond quasi-tangential laser ablation. This rapid prototyping approach for small-scale production decreases the development-time cycle tremendously and trumps conventional approaches. Moreover, a comprehensive parameter study for radial and tangential ablation with single- and multi-pulse is presented. A process achieving an ablation rate of 1 mm3 min−1 with a surface roughness Ra of 0.2 μm is introduced. The meta-stable tetragonal phase of the ceramic persists and is assessed via Raman spectroscopy. The small heat-affected zone is subsequently ablated with a radial laser process step. Hence, high-precision dental implants are producible with a mean error of smaller 5 μm over the complete contour.

Resting-state functional magnetic resonance imaging (fMRI) examines functional connectivity between brain regions by measuring spontaneous fluctuation of blood-oxygen-level dependent (BOLD) signal while subjects are at rest. Recent studies have revealed that neurodegenerative diseases are associated with abnormalities in resting-state functional connectivity. This thesis work aimed to develop a high-throughput preprocessing pipeline for minimizing spatial and temporal artifacts in resting-state fMRI data. The building blocks and cluster computing capabilities of the pipeline are discussed in detail. In an effort to validate this pipeline, a seed-based analysis was performed on preprocessed data using 3 seeds placed in the posterior cingulate cortex (PCC), supplementary motor area (SMA) and inferior parietal sulcus (IPS). These 3 seeds represent the core components of the default mode network (DMN) and task-positive network (TPN), two of the most commonly examined resting-state networks. Consistent with literature, results indicate that activity in the PCC is functionally correlated to regions of the DMN and anti-correlated to regions of the TPN, whereas activities in the SMA and IPS are functionally correlated to regions of the TPN and anti-correlated to regions of the DMN. These functional connectivity patterns were consistent across scans on both group-level and subject-level. This preprocessing pipeline will support researchers and clinical collaborators of Medical Image Analysis Lab (MIAL) in their analysis of resting-state functional connectivity.

The purpose of this paper is to propose and develop a large strain embedded finite element formulation that can be used to explicitly model axonal fiber bundle tractography from diffusion tensor imaging of the brain. Once incorporated, the fibers offer the capability to monitor tract-level strains that give insight into the biomechanics of brain injury. We show that one commercial software has a volume and mass redundancy issue when including embedded axonal fiber and that a newly developed algorithm is able to correct this discrepancy. We provide a validation analysis for stress and energy to demonstrate the method.

Copyright © 2018 John Wiley & Sons, Ltd. Voxel-based micro-finite-element (μFE) models are used extensively in bone mechanics research. A major disadvantage of voxel-based μFE models is that voxel surface jaggedness causes distortion of contact-induced stresses. Past efforts in resolving this problem have only been partially successful, ie, mesh smoothing failed to preserve uniformity of the stiffness matrix, resulting in (excessively) larger solution times, whereas reducing contact to a bonded interface introduced spurious tensile stresses at the contact surface. This paper introduces a novel “smooth” contact formulation that defines gap distances based on an artificial smooth surface representation while using the conventional penalty contact framework. Detailed analyses of a sphere under compression demonstrated that the smooth formulation predicts contact-induced stresses more accurately than the bonded contact formulation. When applied to a realistic bone contact problem, errors in the smooth contact result were under 2%, whereas errors in the bonded contact result were up to 42.2%. We conclude that the novel smooth contact formulation presents a memory-efficient method for contact problems in voxel-based μFE models. It presents the first method that allows modeling finite slip in large-scale voxel meshes common to high-resolution image-based models of bone while keeping the benefits of a fast and efficient voxel-based solution scheme. ispartof: INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING vol:115 issue:4 pages:411-426 status: published

In this paper we present a comprehensive description of the design, fabrication and operation of an electrified Lab-on-a-Disc (eLoaD) system. The smart platform is developed to extend conventional Lab-on-a-Disc applications with an electronic interface, providing additional flow control and sensing capabilities to centrifugal microfluidics platforms. Wireless power is transferred from a Qi-compliant transmitter to the eLoaD platform during rotation. An Arduino-based microcontroller, a Bluetooth communication module, and an on-board SDcard are integrated into the platform. This generalises the applicability of the eLoaD and its modules for performing a wide range of laboratory unit operations, procedures, or diagnostic assays, all controlled wirelessly during spinning. The lightweight platform is fully reusable and modular in design and construction. An interchangeable and non-disposable application disc is fitted with the necessary sensors and/or actuators for a specific assay or experiment to be performed. A particular advantage is the ability to continuously monitor and interact with LoaD experiments, overcoming the limitations of stroboscopy. We demonstrate the applicability of the platform for three sensing experiments involving optical, electrochemical, and temperature detection, and one actuation experiment involving controlled heating/cooling. The complete electronic designs and example programming codes are extensively documented in the supplementary material for easy adaptation.

Accurate estimation of the position and orientation (pose) of a bone from a cluster of skin markers is limited mostly by the relative motion between the bone and the markers, which is known as the Soft Tissue Artifact (STA). This work presents a method, based on continuum mechanics, to describe the kinematics of a cluster affected by STA. The cluster is characterized by Triangular Cosserat Point Elements (TCPEs) defined by all combinations of three markers. The effects of the STA on the TCPEs are quantified using three parameters describing the strain in each TCPE and the relative rotation and translation between TCPEs. The method was evaluated using previously collected ex-vivo kinematic data. Femur pose was estimated from 12 skin markers on the thigh, while its reference pose was measured using bone pins. Analysis revealed that instantaneous subsets of TCPEs exist which estimate bone position and orientation more accurately than the Procrustes Superimposition applied to the cluster of all markers. It has been shown that some of these parameters correlate well with femur pose errors, which suggests that they can be used to select, at each instant, subsets of TCPEs leading an improved estimation of the underlying bone pose.

The application of continuum manipulators as assistive robots is discussed and tested through the use of Bendy ARM, a tendon-driven continuum manipulator prototype. Two rounds of user testing were completed to evaluate the potential of this robot to aid disabled individuals in the completion of activities of daily living. In the first round of user testing, 14 able-bodied subjects successfully completed the prescribed task (pick-and-place) using multiple control schemes after being given a brief introduction and one minute of practice with each scheme. In the second round of user testing, subjects chosen from the first round of testing (n = 3) demonstrated between 29.45 and 48.91 percent improvement in completion time across three sessions (twelve trials total) of a peg-in-hole task, and between 8.39 and 33.81 percent improvement across two sessions (six trials total) of a task involving opening and closing a drawer. Based on these results, it is posited that continuum manipulators merit further consideration as a safer and more cost-effective alternative to existing commercially available assistive robotic manipulators., National Science Foundation under Grant No. CNS-1560219

Quasi-static, pulmonary pressure-volume (P-V) curves over an inflation-deflation cycle are analyzed using a respiratory system model (RSM), which had been developed for quantitative characterization of the mechanical behavior of the total respiratory system. Optimum mechanical ventilation setting of Positive End Expiratory Pressure (PEEP) for total alveolar recruitment is quantified based on the existing P-V curves of healthy and injured animal models. Our analytical predictions may contribute to the optimization of mechanical ventilation settings for the Acute Respiratory Distress Syndrome (ARDS) patients.

The design and fabrication of reconfigurable, modular paperfluidics driven by a prefabricated reusable block library, asynchronous modular paperfluidic linear instrument-free (Ampli) block, are reported. The blocks are inspired by the plug-and-play modularity of electronic breadboards that lower prototyping barriers in circuit design. The resulting biochemical breadboard is a paperfluidic construction set that can be functionalized with chemical, biological, and electrical elements. Ampli blocks can form standard paperfluidic devices without any external instrumentation. Furthermore, their modular nature enhances fluidics in ways that fixed devices cannot. The blocks' ability to start, stop, modify, and reverse reaction flows, reagents, and rates in real time is demonstrated. These enhancements allow users to increase colorimetric signals, fine tune reaction times, and counter check multiplexed diagnostics for false positives or negatives. The modular construction demonstrates that field-ready, distributed fabrication of paper analytical systems can be standardized without requiring the “black box” of craft and technique inherent in paper-based systems. Ampli assembly and point-of-care redesign extends the usability of paper analytical systems and invites user-driven prototyping beyond the lab setting demonstrating “Design for Hack” in diagnostics.

The characterization of biological tissues depends on accurate measurements of deformation and strain, but less attention has been given to the role of out-of-plane deformation in ligament strain. The objective of this study was to investigate the influence of out-of-plane deformation on surface strain measurements in healthy and damaged ligaments. Tensile tests on five porcine posterior cruciate ligaments (PCL) were performed before and after damage using the femur – PCL – tibia construct. Damage was simulated by loading the ligament to its maximum force capacity. Digitized surface dots were tracked using an optical motion capture system. The transverse strain (ε_xx), longitudinal strain (ε_yy), and shear strain (γ_xy) distributions on the ligament surface were obtained for the control and damaged states using two-dimensional (2d) strain and three-dimensional (3d) strain measurements. There was no significant difference between the 2d and 3d strains in the control state for all three strains. However, the value and location of the peak strain values (tensile and compressive) in ligament surfaces did change. The 2d peak tensile strain was both over and under-estimated, compared to 3d strain, when out of plane deformation was included for ε_xx and ε_yy; but consistently overestimated for positive γ_xy. The percentage of damaged regions, quantified as a loss in tensile strength, after damage was overpredicted by 2d strain for ε_yy. Care should be taken when using 2d surface strain as peak values and local damage is sensitive to out-of-plane deformation.

Knee pain and injuries are very common in athletes. Anterior cruciate ligament (ACL) injury is one of the most important reason of knee acute and chronic pains. As ACL plays a significant role in knee stability and due to amount of reported ACL related injuries, much effort has been placed on finding proper and on time diagnosis and treatment of these injuries. Arthrometric methods are the most non-invasive reliable diagnosis option; however they are trusted to distinguish partial injuries from intact joint and instead expensive and more time consuming imaging diagnosis techniques (i.e MRI) are used. Arthromery results can be investigated by quantifying the tests using computer simulations; so far few studies have been conducted toward this goal.In this study a two dimensional finite flement (FE) model of knee joint under standard arthrometry state (by a KT-2000 arthrometer) was built. This model was then used to evaluate the effect of precise modeling of tibiofemoral contact-surface geometry with considering flexible articular cartilage in the joint. The results revealed that exact modeling of the contact geometry highly influences the simulation results. In the next step, the built model was used in a stochastic modeling with the experimental data obtained from literature in order to simulate a real diagnosis circumstance and to provide a statistical comparison between seven different levels of ACL injury. The result of this simulation shows that although arthrometry may be able to distinguish partial injuries from intact in most cases leading to less ACLD with appropriate treatment, but it is hard to tell anything about the level of injury. To prevent the costs of imaging techniques moving towards the introduction of new measuring methods (or newly defined identifiers) or using intelligent processing of currently obtained data is suggested.

The automatic recognition of Activities of Daily Living (ADL) with a multi-sensor mobile device that can acquire different types of sensors' data, and rely on the use of machine learning methods to handle the recognition of ADL with reliable accuracy. This paper focuses on the literature review of the existing methods to make the identification of ADL in order to assess the efficiency of the different methods for the identification of ADL and their environments using off-the-shelf mobile devices. Data acquired from several sensors can be used for the identification of ADL, where the motion, magnetic and location sensors handle the recognition of activities with movement, and the acoustic sensors handle the recognition of activities related with the environment. Therefore, the main purpose of this study is to present a review of the machine learning methods already used on this field, relating them with the accuracy and number of ADL recognized.

Objective: To investigate the stability of four tension band wiring configurations alone without the contributions of K-wire stabilization. Study design: ex vivo experimentalSample population: Sixty-four tension band wiring constructsMethods: Four tension band configurations were applied to a metal trochanteric osteotomy model based on a canine femur: figure-of-eight with one twist (OT), figure-of-eight with two twists (TT), dual interlocking single loop (DISL), and double loop (DL). Configurations were mechanically tested under both monotonic loading (n = 8 per configuration) and incremental cyclic loading (n = 8 per configuration). Initial tension after tying, residual tension remaining after each cycle, and failure load at 2 mm of displacement (considered equivalent to clinical failure) were recorded. Results: The initial tension and the load to 2 mm of displacement was lower for OT wires compared to TT wires. The DL was the strongest and most stable configuration, generating greater initial tension, maintaining a greater percentage of residual tension under incremental cyclic loads, and resisting higher load before failure at 2 mm. Failure load was highly correlated with initial tension. Conclusion: This model enabled evaluation of tension band wire configuration independent of the fixation pin portion of the construct. Wire configurations that can be tightened to a greater tension during tying, like the DL, are better able to resist the tensile loads experienced by the construct. Clinical impact: In clinical situations where high tensile loads are expected, a tighter, more secure tension band wire configuration may be warranted.

Tissue scaffolds fabricated by three-dimensional (3D) bioprinting are attracting considerable attention for tissue engineering applications. Because the mechanical properties of hydrogel scaffolds should match the damaged tissue, changing various parameters during 3D bioprinting has been studied to manipulate the mechanical behavior of the resulting scaffolds. Crosslinking scaffolds using a cation solution (such as CaCl2) is also important for regulating the mechanical properties, but has not been well documented in the literature. Here, the effect of varied crosslinking agent volume and crosslinking time on the mechanical behavior of 3D bioplotted alginate scaffolds was evaulated using both experimental and numerical methods. Compression tests were used to measure the elastic modulus of each scaffold, then a finite element model was developed and a power model used to predict scaffold mechanical behavior. Results showed that crosslinking time and volume of crosslinker both play a decisive role in modulating the mechanical properties of 3D bioplotted scaffolds. Because mechanical properties of scaffolds can affect cell response, the findings of this study can be implemented to modulate the elastic modulus of scaffolds according to the intended application.

Over the past two decades, significant progress has been achieved in the field of tissue engineering (TE) to restore/repair damaged tissues or organs and, in this regard, scaffolds made from biomaterials have played a critical role. Notably, recent advances in biomaterials and three-dimensional (3D) printing have enabled the manipulation of two or more biomaterials of distinct, yet complementary, mechanical and/or biological properties to form so-called hybrid scaffolds mimicking native tissues. Among various biomaterials, hydrogels synthesized to incorporate living cells and/or biological molecules have dominated due to their hydrated tissue-like environment. Moreover, dispensing-based bioprinting has evolved to the point that it can now be used to create hybrid scaffolds with complex structures. However, the complexities associated with multi-material bioprinting and synthesis of hydrogels used for hybrid scaffolds pose many challenges for their fabrication. This paper presents a brief review of dispensing-based bioprinting of hybrid scaffolds for TE applications. The focus is on the design and fabrication of hybrid scaffolds, including imaging techniques, potential biomaterials, physical architecture, mechanical properties, cell viability, and the importance of vessel-like channels. The key issues and challenges for dispensing-based bioprinting of hybrid scaffolds are also identified and discussed along with recommendations for future research directions. Addressing these issues will significantly enhance the design and fabrication of hybrid scaffolds to and pave the way for translating them into clinical applications.

Several types of sensors have been available in off-the-shelf mobile devices, including motion, magnetic, vision, acoustic, and location sensors. This paper focuses on the fusion of the data acquired from motion and magnetic sensors, i.e., accelerometer, gyroscope and magnetometer sensors, for the recognition of Activities of Daily Living (ADL) using pattern recognition techniques. The system developed in this study includes data acquisition, data processing, data fusion, and artificial intelligence methods. Artificial Neural Networks (ANN) are included in artificial intelligence methods, which are used in this study for the recognition of ADL. The purpose of this study is the creation of a new method using ANN for the identification of ADL, comparing three types of ANN, in order to achieve results with a reliable accuracy. The best accuracy was obtained with Deep Learning, which, after the application of the L2 regularization and normalization techniques on the sensors data, reports an accuracy of 89.51%., arXiv admin note: substantial text overlap with arXiv:1711.00124, arXiv:1711.00104; text overlap with arXiv:1711.00096

We here developed an automated well plate imaging system to eliminate the requirement for continuous human operation, thus freeing up the valuable time of a scientific researcher and removing the possibility of fatigue-induced human error. Specifically, we created a prototype system with programmed two-dimensional movement, automated calibration, variable plate configuration compatibility, variable path feasibility, reliable well plate image capture, and an intuitive graphical user interface. Successful implementation of our device would immediately benefit laboratory scientists, giving them more time to pursue the next biomedical breakthroughs.

Existing methods which compensate for the Soft Tissue Artifact (STA) in optoelectronic motion measurements estimate the rigid motion of a nearly rigid underlying body segment based on analysis of the motion of all fiducial markers. The objective of the proposed Triangular Cosserat Point Elements (TCPE) method is to estimate the motion of the underlying body segment even when the STA in the entire cluster of markers can be large. This is accomplished by characterizing the cluster of markers with TCPEs defined by triangles based on all combinations of three markers. Then, scalar deformation measures characterizing the magnitudes of strain and relative rotation of pairs of TCPEs are defined for each TCPE. These deformation measures are used to define a filtered group of TCPEs which best represents the motion of the underlying body segment. The method was tested using an experimental setup that consists of a rigid pendulum with a deformable 300 ml silicone breast implant attached to it as a simulation of the soft tissue around a bony segment. The rotation angles extracted from markers on the deformable implant were compared with simultaneous measurements of the rigid pendulum using an optoelectronic system. Analysis of the experimental data shows that this filtering process substantially reduces the error due to the STA even though the data set includes large deformations. In particular, the analysis shows that the error reduction using the TCPE approach is larger than the reductions obtained using standard least-squares minimization methods.

Simon game that will help people with muscular disability. have more fun doing there daily muscle workout by playing a game instead of doing something very repetitive. our game is more unique then a normal Simon game as you can put the buttons which are on stands that you can put anywhere.

The aim of this proposal is to implement MR temperature measurement techniques that accelerate data acquisition speed and are robust to motion-related errors. Collaboration between the research groups at the University of Utah and the University of Geneva will facilitate the transmission, implementation, and further development of these site-specific MR temperature measurement techniques and will accelerate the two goups' respective goals of using MRgHIFU to treat tumors in breast and liver.

Parkinsons disease (PD) is a degenerative condition of the nervous system, which manifests itself primarily as muscle sti ness, hypokinesia, bradykinesia, and tremor. In patients su ering from advanced stages of PD, Deep Brain Stimulation neurosurgery (DBS) is the best alternative to medical treatment, especially when they become tolerant to the drugs. This surgery produces a neuronal activity, a result of electrical stimulation, whose quanti cation is known as Volume of Tissue Activated (VTA). To locate the VTA correctly in the cerebral volume space, one should be aware of exactly the location on the tip of the DBS electrodes, as well as their spatial projection. In this paper, we automatically locate DBS electrodes using a thresholdbased medical imaging segmentation methodology, determining the optimal value of this threshold adaptively. The proposed method allows the localization of DBS electrodes in Computed Tomography (CT) images, with high noise tolerance, using automatic threshold detection methods.

Through the use of a cadaveric porcine model, forces necessary for manipulation of the abdominal organs were evaluated using an instrumented probe. Additionally, forces for tissue puncture, knot tightening, and suture breakage have been measured in order to determine the requirements placed upon the design of novel robotic surgical tools. The break forces for a variety of suture sizes and types were evaluated including sizes 3-0 through 7-0 polypropylene, size 1 polybutestor, size 4-0 chromic gut, and size 6-0 braided polyester. Tests of the tissue puncture force and knot tightening forces were carried out using the same instrumented probe, while the suture break forces were measured using a tension testing machine. The measured forces were found to compare well against the literature and provide a good basis from which to design robotic surgical tools with the appropriate capabilities.

Optoelectronic plethysmography (OEP) is a noninvasive method for assessing lung volume variations and the contributions of different anatomical compartments of the chest wall (CW) through measurements of the motion of markers attached to the CW surface. The present study proposes a new method for analyzing the local CW kinematics from OEP measurements based on the kinematics of triangular Cosserat point elements (TCPEs). 52 reflective markers were placed on the anterior CW to create a mesh of 78 triangles according to an anatomical model. Each triangle was characterized by a TCPE and its kinematics was described using four time-variant scalar TCPE parameters. The total CW volume ([Formula: see text]) and the contributions of its six compartments were also estimated, using the same markers. The method was evaluated using measurements of ten healthy subjects, nine patients with Pompe disease, and ten patients with Duchenne muscular dystrophy (DMD), during spontaneous breathing (SB) and vital capacity maneuvers (VC) in the supine position. TCPE parameters and compartmental volumes were compared with [Formula: see text] by computing the phase angles [Formula: see text] (for SB) and the correlation r (for VC) between them. Analysis of [Formula: see text] and r of the outward translation parameter [Formula: see text] of each TCPE revealed that for healthy subjects it provided similar results to those obtained by compartmental volumes, whereas for the neuromuscular patients the TCPE method was capable of detecting local asynchronous and paradoxical movements also in cases where they were undistinguished by volumes. Therefore, the TCPE approach provides additional information to OEP that may enhance its clinical evaluation capabilities.

Through the use of a cadaveric porcine model, forces necessary for manipulation of the abdominal organs were evaluated using an instrumented probe. Additionally, forces for tissue puncture, knot tightening, and suture breakage have been measured in order to determine the requirements placed upon the design of novel robotic surgical tools. The break forces for a variety of suture sizes and types were evaluated including sizes 3-0 through 7-0 polypropylene, size 1 polybutestor, size 4-0 chromic gut, and size 6-0 braided polyester. Tests of the tissue puncture force and knot tightening forces were carried out using the same instrumented probe, while the suture break forces were measured using a tension testing machine. The measured forces were found to compare well against the literature and provide a good basis from which to design robotic surgical tools with the appropriate capabilities.

Skeletal muscle tissue presents a highly asymmetrical behaviour when passively loaded in tension or compression, but no structural model addressing this has been reported. Passive skeletal muscle derives its structural response from titin filaments, collagen fibresin the connective tissue and incompressibility due to high fluid content. The objective of this paper is to develop a micro-structurally based mathematical model to predict the known tension-compression asymmetry. Such a model is a precursor to future constitutive formulations for finite element modelling.

Materials such as elastomeric foams, lattices, and cellular solids are capable of undergoing large elastic volume changes. Although many hyperelastic constitutive formulations have been proposed for deviatoric (shape changing) behaviour, few variations exist for large deformation volumetric behaviour. The first section of this paper presents a critical analysis of current volumetric hyperelastic models and highlights their limitations for large volumetric strains. In the second section of the paper we propose three novel volumetric strain energy density functions, which: (1) are valid for large volumetric deformations, (2) offer separate control of the volumetric strain stiffening behaviour during shrinkage (volume reduction) and expansion (volume increase), and (3) provide precise control of non-monotonic volumetric strain stiffening. To illustrate the ability of the novel formulations to capture complex volumetric material behaviour they are fitted and compared to a range of published experimental data.

To manage complex aortic arch disease using minimally invasive techniques, interventionalists have reported the use of multiple stent-graft devices deployed in a parallel configuration. The structural device-device and device-artery interactions arising during aortic arch parallel endografting, also known as chimney thoracic endovascular aortic repair (ch-TEVAR), is not well understood. Through the use of a radial force testing system we sought to characterise both the loading and deformation behaviour of parallel endografts in representative ch-TEVAR configurations. Four commercially available devices (Bentley BeGraft, Gore TAG, Gore Viabahn, and Medtronic Valiant) were subjected to uniform radial load individually, and in six combinations, to quantify loading profiles. Image data collected during testing were analysed to evaluate mechanical deformations in terms of gutters, chimney and main endograft compression, as well as graft infolding. Parallel endografting was found to increase radial loads when compared to standard TEVAR. Chronic outward force during ch-TEVAR was dependent on main endograft manufacturer, with TAG combinations leading to consistently higher loads than Valiant, but independent of chimney graft type. Endograft deformations were dependent on chimney graft type, with Viabahn combinations presenting with lower gutter areas and increased lumen compression than BeGraft. Chimney graft deformations were also influenced by deployment arrangement in the case of double ch-TEVAR. This study emphasizes the significant variability in both radial loads and mechanical deformations between clinically relevant ch-TEVAR configurations.

As far as engineering fields go, there is perhaps no branch of engineering that is as exciting or as futuristic in its nature as mechanical engineering. Interestingly, mechanical engineering is in fact responsible for far more around us than many of us are even aware of. Whether it is the gas fireplaces in homes around the world, or the advancements in robotics that are spelling a clear pivot towards technological enhancement more and more all the time. But what exactly is mechanical engineering, and what are some of its current focuses?

It has been started on December 31, 2019 with a pneumonic case reported in Hubei, China and now it has taken the shape of a global pandemic COVID-19. The cause behind this pandemic is a deadly Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), which belongs to a family of viruses that has a history of outbreaks in 2003 with SARS-CoV and in 2012 with the Middle East Respiratory Syndrome MERS-CoV. The potential modes of transmitting SARS-CoV-2 have been identified as direct contact respiratory droplets, and aerosols. Now the studies are coming from different parts of the world identifying the traces of SARS-CoV-2 in water bodies. Some studies are also predicting the spread of COVID-19 through water. It could a big matter of concern to the countries with approaching south-west monsoon. Thus a mitigation strategy must be made to combat COVID-19 in such countries.

Auxetic behaviour, the unphysical transverse expansion during uniaxial tension, is a common and undesirable feature of classical anisotropic hyperelastic constitutive models for soft tissue. In this study we uncover the underlying mechanism of such behaviour; high levels of in-plane compaction occurs due to increasing tension in strain-stiffening fibres, leading to unphysical out-of-plane expansion. We demonstrate that auxetic behaviour is primarily influenced by the ratio of fibre to matrix stiffness, and is accentuated by strain-stiffening fibres in a constant stiffness matrix (e.g., the widely used neo-Hookean matrix with exponentially stiffening fibres). We propose a new bilinear strain stiffening fibre and matrix (BLFM) model which allows close control of the fibre-matrix stiffness ratio, thereby robustly eliminating auxetic behaviour. We demonstrate that our model provides accurate prediction of experimentally observed out-of-plane compaction, in addition to stress-stretch anisotropy, for arterial tissue subjected to uniaxial tension testing.