Central venous catheters (CVCs) are used as a way to provide adequate access of blood flow for hemodialysis, a common treatment for end-stage kidney disease. During hemodialysis, the catheter must circulate up to 300 mL/min [1] of blood flow to the extracorporeal artificial kidney. Catheters contain two lumens: the inflow lumen provides flow to the artificial kidney, and the outflow lumen returns it to the patient’s circulation. Although catheters are used in the treatment of patients of all ages, this study is motivated by the use of central venous catheters for pediatric applications; the catheter types and calibers available for children are much more limited than for adults, thereby placing children in a further disadvantage and potentially subjecting them to increased risk of complications.

Recently MR image based computational models are being developed to assist targeted drug delivery in the brain by helping determine appropriate catheter position, drug dose among others to achieve the desired drug distribution [1–3]. Such a planning might be important to prevent damaging healthier tissues because many of the drugs (e.g. chemotherapeutic agents) are usually toxic and needs to be concentrated in specific regions of interest (e.g. tumor). However, for the image based model to make accurate predictions, it is important to segment the image and assign appropriate tissue properties such as hydraulic conductivity which are known to vary significantly within the brain. For example, it has been experimentally found that drugs injected into brain parenchyma get preferentially transported along the white matter tracts compared to the gray matter regions [4]. Segmenting MR images is a challenging task since the pixel intensities between different regions often overlap, hence traditional approaches based on thresholds might not provide reliable results. In this study, we used multi-layered perceptron (MLP) neural network to segment rat brain MR images into 3 different regions namely white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF).

Carotid artery stenting (CAS) is relatively new procedure introduced to treat severe carotid atherosclerotic disease for high risk patient categories. The advantages of this technique are its minimal invasiveness, easiness of the procedure and the short hospitalization compared to surgical option. However, perioperative complications, such as stroke, can lead to failure of the procedure and long terms effects of the procedure are not completely understood. It is not unrealistic to assume that the mechanical changes of the pathophysiological environment at the stented vessel can induce tissue damage and promote remodeling and restenosis but how these factor (inter)act is still a matter of debate.

The retina is a light-sensitive tissue layer that lines the inside of the eye and relays visual information directly to the brain via the optic nerve. Retinal detachment occurs when the retina is lifted or pulled from its physiological location. This condition can result in partial or total vision loss. Retinal detachmentis a leading cause of permanent vision loss.

Magnetic separation is one of the effective ways to separate specific biological entities such as DNA/RNA, bacteria, and cells from their native environment for subsequent downstream analysis. The process involves the labeling of the desired biological entity with magnetic beads followed by separating the tagged entities via a magnetic separation device. In conventional tube-based magnetic separation, magnetically labeled biological entities are retained on the inner wall of the tube by applying an external magnet, while the supernatant is decanted off. Removing the tube from the magnetic field enables resuspension of the target entity. Although widely used, there are limitations to the conventional magnetic separation method. For example, there is a significant sample loss due to multiple sample handling, washing, and transfer. In addition, manual magnetic separation systems are labor intensive and their effectiveness is user-dependent.

Liver has complex structure of blood vessels. There are two inlets of the blood flow in a liver. One is hepatic artery in which the blood flow from a heart to supply oxygen. Another is portal vein in which the blood flow from the digestive organs to maintain the metabolic and the detoxification processes. These vessels join at hepatic lobule which is consisted by hepatocyte. The hepatic lobule has a central vein and the central veins drain the blood flow into a hepatic vein. The hepatic vein is unique outlet of the blood flow of the liver.

Advanced simulation techniques in computer-assisted surgery is not only the key element towards development of computer based systems for optimized implant design, but they will also allow surgeons to reliably replace the damaged joints, even when significant bone loss has occurred. Since the main objective of the surgical procedure is to accurately replicate the native articulation of the elbow, the overall success of the joint arthroplasty is decisively influenced by the preoperative planning procedure aiming to establish the presence of a feasible position of the implant that will essentially cause a minimal malalignment of the prosthetic flexion-extension (FE) axis of the joint with respect to the native one. Any malalignment between native and artificial axes will eventually alter the kinematics of the joint and will lead to implant failures.

Photopolymerization methods such as multiphoton polymerization have been used successfully to create bioactive patterned scaffolds with micron-scale resolution capable of supporting cell growth and differentiation for engineered tissue. [1] They have also been shown effective for fabrication of a variety of MEMS devices. [2] Currently, multiphoton polymerization and similar technologies require a bulky and expensive optical system based on a femto- or picosecond pulsed laser and an XYZ arrangement of high-resolution translating stages. [3] Such systems are currently prohibitive in both cost and effort required to assemble, calibrate, and maintain. Consolidating optical components and motors into a smaller, less-complex device may facilitate the manufacture of customized tissue engineered constructs and MEMS devices on-site in more remote locations on an as-needed basis.

The MyotonPro® (Myoton AS, Tallinn, Estonia) is commonly used to quantify stiffness properties of living tissues in situ. Current studies quantify the dynamic stiffness properties of living tissues, but do not validate or compare these measurements to a standardized method. Additionally, living tissue, being dynamic in nature, presents much variability in data collection. To address these issues this study focuses on the repeatability and reproducibility of the MyotonPro® on polymeric gel-based tissue phantoms. In addition, a correlation study is also performed to translate dynamic stiffness to a more standardized property, Young’s modulus. Such studies help to confirm the reliability of the measurements obtained in situ.

Very late stent thrombosis (ST) stent fracture (SF) increases restenosis rate of permanent drug eluting stents (DES). In fact, permanent stents after arterial remodeling (change of artery dimensions during atherosclerosis) process becomes a supportive part inside our body and this idea lead us to develop biodegradable stents which support till arterial remodeling and progressively degrade thereafter. In this research, cold gas dynamic spray technique, simply referred to as cold spray is introduced to spray micro particles on metallic plane and cylindrical substrate. Reference material for permanent stent, stainless steel, 316L is mixed with pure iron in different proportions to induce microgalvanic corrosion effect on as sprayed specimens. Although annealed 316L coatings indicate better ultimate strength, porosity and ductility, their degradation study signifies their poor degradability in Hank’s physiological solution. In contrast to that, immersion and potentiodynamic polarization tests under Hank’s physiological solution indicate that corrosion rate of as sprayed composite increases as amount of iron increases. More iron particles release more iron ions and increases corrosion rate in hanks solution.

Obesity is commonly considered a risk factor for the development of knee osteoarthritis [1]. Previous studies have shown that reductions in body weight correspond to reductions in total knee joint compressive forces (as calculated by inverse dynamics) [2–4]. A recent study showed that external knee load measurements are not strong predictors of internal knee contact forces [5]. Therefore, direct measurement of knee contact force is important for understanding how body weight changes impact knee joint loading. Force-measuring knee implants can directly measure internal knee contact forces [6].

Heat and perspiration inside the prosthesis cause discomfort and adherence problems for lower limb amputees. To bench test new prosthetic socket interventions, we developed a thermal residual limb manikin (TRLM) and used it to compare two novel cooling technologies: (1) a vacuum pump which provides ventilation across the skin (FLOW) and (2) a liquid cooling sleeve (SLEEVE). Power to maintain TRLM core temperature was measured to indicate cooling effectiveness. Power increased by 7% and 8% after 90 minutes of convective cooling and evaporative cooling, respectively, with the FLOW system. Power increased by 28% with the SLEEVE system.

Computational methods are the tool of choice for the study of physics phenomena in many fields of scientific endeavor. To guarantee the reliability of the results of computational analyses, it is crucial that mathematical models are validated and numerical methods are verified . A verified method is capable of correctly solving the problem equations, while a valid model is able to correctly describe the features of the problem (i.e. it uses the right equations). In this paper we: (i) verify and validate an open source computational fluid dynamics (CFD) framework for the solution of problems of interest in hemodynamics and (ii) provide a report on the methodology that we use, to make our experiences reproducible.

A new testing method with an anatomic bench model was developed to replace cadaver studies as a means to validate lead design/development. The test methodology was verified with cadaver study results and physician feedback. Four different lead designs were characterized through this methodology. The methodology could save one year of lead development time and $60k in costs.

Loss of muscle mass due to reduced mechanical loading is a critical issue for long duration spaceflight on the International Space Station (ISS) [1]. To address this issue, NASA has developed the Advanced Resistive Exercise Device (ARED) that allows astronauts to perform resistance exercise on the ISS. To minimize force transmission to the ISS, the ARED is mounted to a vibration isolation system (VIS). During squat exercise, ARED rotates relative to the ISS, functioning like a nutcracker to compress the astronaut with a load provided by two vacuum cylinders. Though the ARED is an effective exercise countermeasure device, the extent to which squat exercise on the ISS achieves Earth-equivalent muscle moments remains unknown.

A microchannel-based hemodialyzer offers a novel approach to hemodialysis practice and holds many promises to improve kidney patients’ life quality and dialysis treatment efficiency. The hallow fiber hemodialyzer, a conventional dialysis device, has certain limitations including non-uniformity of the dialysate flow path which necessitates the use of a high dialysate flow rate. The microchannel-based hemodialyzer with flat membranes remarkably improves the mass transfer characteristics and enables the design of a smaller and less expensive unit with lower dialysate-to-blood flow rate ratios [1, 2]. In the microchannel-based design, successive stacked layers alternate between blood flow and dialysate flow. A porous membrane between these layers allows for the transport of toxins from blood side to dialysis fluid side. A schematic view of a single layer is shown in Fig. 1.

Mild traumatic brain injuries (mTBI) are common in soldiers and athletes, and can affect many areas of a person’s daily life including gait [1]. Current methods of measuring gait parameters involve expensive optical motion capture systems, time intensive setup, wires, complicated filtering techniques, and a laboratory setting. A wearable and wireless motion analysis system would allow gait analysis to be performed outside of a laboratory setting during activities of daily living, in a clinical setting or on a football field. The purpose of this study was to develop and verify an algorithm to calculate knee flexion during slow gait, particularly during terminal stance and pre-swing phases, using wireless wearable sensors.

Capsule Endoscopy (CE) has been used in last 10 years in medical diagnosis of intestine disease such as obscure gastrointestinal bleeding(OGIB)[1]. An estimated 19 million Americans[2] suffer from these kinds of small intestine disease. The major limitation of this method is that the incomplete examination found in one research is about 20% of 2300 examinations. Also it results in a small risk of obstructive symptoms. When retention happens, high-cost, quick surgical intervention is required.

Stenting technology has emerged as an effective alternative for treating arterial stenosis, which recovers blood fluency through mechanical scaffold using struts. Different kinds of endovascular stents cause varying degrees of injury on the artery wall, inducing different ratios of post-operative in-stent restenosis (ISR). Therefore, the design of stent structure has a significant influence on the therapeutic effect of stent intervention. From the viewpoint of solid mechanics, the artery is subjected to long-term press by stent strut after intervention, leading to external mechanical force acting on artery. Straightening, mechanical stress, and stress concentration occurred, causing in-stent intimal hyperplasia extremely, which consequently induce ISR. From the viewpoint of hemodynamics, hemodynamic environment is changed to some extent after stenting. As a result, local blood flow is changed greatly. Vortex and low WSS occur, promoting thrombosis and intimal hyperplasia, which induce ISR more easily. To investigate the effect of stents with different links on treating stenotic vertebral artery and the relation between the shape of link and ISR, as well as provide scientific guidelines for designing stent structure and selecting stent in clinical procedure, numerical simulations of solid mechanics and hemodynamics were performed in this paper, which coupled the boundaries of stent, plaque and blood in the stented vertebral arteries using three kinds of stent with different links.

Movement disorders associated with Parkinson’s Disease include tremor, slowness of movement, lack of movement, and involuntary movement. During the clinicial assessment of Parkinson’s disease, patients typically self-report their daily clinical states, which includes the amount of time they experienced dyskinesia ( i.e. , involuntary twisting or writhing movements). The clinician then uses the self-reported information to adjust treatments in the form of medication or deep brain stimulation. Because the accuracy of the self-report is often very low, the treatment modification may not be optimal. The overall objective of this study is to develop computational algorithms that automatically identify periods of dyskinesia in patients of Parkinson’s disease from body-worn accelerometer data during activities of daily living (ADL). Specifically, unlike previous studies which used supervised learning algorithms ( i.e. , knowledge of prior events is used to “train” the algorithm to identify future events), our goal is to classify the periods of dyskinesia solely by identifying key features from the accelerometer data. Our desired long-term outcome is to provide clinicians a timeline showing the presence of dyskinesia over an extended time period without the clinician having to train the computational algorithm by examining video for each patient.