A New Paradigm for Neurological Lead Cyclic Testing

The feasibility of electrical stimulation of the nervous system to treat chronic pain was proven with implantation of the first device for this purpose by Norm Shealy, MD in 1967. Since then, neurological stimulation has become a standard therapy for pain management.

Biomechanical Evaluation of a Wide-Diameter Short Dental Implant for Use in Compromised Bone Quality Regions by Finite Element Method

The success rates of dental implant treatments in posterior mandible and maxilla could be compromised due to the increased masticatory forces and poor bone quality. In addition, the length of the implant is limited by maxillary sinus and mandibular canal in these regions. Wide-diameter short (WDS) implants provide a good alternative to increase the stability and the reliability of the implants in such conditions. The objective of this study is to evaluate the biomechanical properties of a wide implant by performing finite element analyses (FEA). Comparison of the strain distribution induced in the bone by a WDS implant and by a narrow-diameter long (NDL) implant, in clinical scenarios exhibiting different amounts of crestal bone, and under varying insertion depths demonstrated that WDS implant can be used safely and should perform as well as its NDL counterpart.

Development of a Multi-Axis Peripheral Stent Durability/Fatigue Test Instrument

Structural failures of metallic stents in peripheral arteries such as the superficial femoral artery (SFA) have challenged industry to devise a suitable mechanical durability/fatigue model to simulate the clinical conditions. Previous mechanical durability testing for stents has consisted of pulsatile fatigue of a straight stent in a straight tube. The stents are distended to diametric levels expected in the target native artery and cycled to duplicate 10 years of simulated life. This is at least 380 million cycles. High speed pulsatile fatigue test instruments have been able to reproduce those distentions at test frequencies of 60 Hz resulting in a simulated 10 year life of less than 90 days.

Sterile Medical Device Package Development: From Concept to Market

Developing the packaging system for medical device products is often an after thought in the product development life cycle. The sterile package is a critical part of the device, as the device must be sterile in order to be used; therefore the package provides the device with utility at the point of use. Although the packaging for a medical device is as critical to the device function as the device itself, the process and methods that must be followed to effectively design, develop, and implement a sterile package assembly are established but often misunderstood. Medical device packaging development is directly related to factors associated with the physiological and pathological environment, the development of the device, and regulatory issues surrounding the possible markets of distribution. It is critical that the proper packaging development be applied to a device to ensure that it is both safe and effective.

Biomechanical Simulations of Bioprosthetic Heart Valve Deformations

Previous research has suggested that the structural deterioration in porcine bioprosthetic heart valves (BHV) may be correlated with the regions of high tensile and bending stresses acting on the leaflets during opening and closing[1, 2]. Stress concentrations within the cusp can either directly accelerate tissue structural fatigue damage, or initiate calcification by causing structural disintegration, enabling multiple pathways of calcification that can lead to valve failure[3,4]. In the case of bovine pericardial heart valve prostheses, structural failure of the leaflets is rare but calcification has been observed. Although details of the process are unclear, it is generally assumed that the design of the pericardial valve, which gives a stress-reduced state of the leaflets, is likely to provide improved performance in long-term applications.

A New Direct Electron Imaging System for Biomedical Applications

High resolution electron imaging of biological assemblies such as proteins, viruses, and cells are important for biomedical diagnosis and drug discovery. We report on the design of a new CMOS direct-detection camera system for electron imaging. The active pixel sensor array includes 512 by 550 pixels, each 5 by 5 μm in size, with a ~8 μm epitaxial layer to achieve an effective fill factor of 100%. Spatial resolution of 2.3 μm for a single incident e- has been measured. A sample image of a mouse’s muscle cell is presented.

Hollow-Fiber Cartridges: Model Systems for Virus Removal From Blood

Aethlon Medical is developing an extracorporeal blood filter as a therapeutic device designed to remove viruses and toxins from the blood of patients. The Hemopurifier is a modified hollow-fiber plasmapheresis cartridge containing an affinity matrix in the extra capillary space. The matrix contains a high mannose specific lectin as the active capture agent. The flow configuration of the device is that of Starling flow. The filter is designed to clear viruses and toxins from blood, delaying illness so the patient’s immune system can fight off the virus. Results to date indicate the efficient removal of a variety of enveloped viruses including HIV, HCV and poxviruses with in vitro evidence indicating the ability to capture Dengue fever virus, measles, mumps, influenza, Ebola and Marburg. Possible additional targets include bioweapons such as smallpox and bacterial toxins. A schematic of the use of the filter in a therapeutic application is shown in figure 1. In order to optimize the design of such a filter, the fluid mechanics of the device is modeled analytically and investigated experimentally. Additional information can be found in Tullis et al. [1], Tullis et al. [2], and Duffin and Tullis [2].

Auxetic Drug-Eluting Stent Design

A cardiovascular stent is a cylindrical wire mesh structure that is permanently introduced into an artery during angioplasty (balloon dilatation) to act as a scaffold, thus preventing elastic recoil and/or sudden collapse of the damaged artery. While cardiovascular stents virtually eliminate elastic recoil and/or collapse of the artery, recognition of the stent as a foreign material triggers a human immune system response causing re-closure, or restenosis, of the artery. A recent advancement to counteract restenosis is to employ drug-eluting stents to locally deliver immunosuppressant and antiproliferative drugs.

Simulation of Renal Stent in Respiration

Atherosclerotic renal artery stenosis is a common manifestation of generalized atherosclerosis and is the most common disorder of the renal arterial circulation. Despite the proven efficacy of surgical revascularization, endovascular therapy has emerged as the preferred strategy for treatment. Balloon-expandable stents for aorta-ostial renal artery stenosis is demonstrated to be a safe and effective therapy [1].

Effect of Surface Treatment on Surface Characteristics and Biocompatibility of AISI 316L Stainless Steel

Surface characteristics are essential in determining the biocompatibility of medical implants. Surface treatments such as mechanical polishing, electropolishing, passivation and plastic strain of AISI 316L stainless steel was found to affect the critical surface tension, with the combined electropolishing and passivation treatment resulting in the most desirable critical surface tension for biocompatibility. AES and XPS analysis showed that electropolishing results in changing the surface chemical composition significantly. There is significant Cr enrichment on the surface, compared to the bulk. The surface Cr and Fe exist as a combination of oxides and hydroxides.