Kotzar 2002 Biomaterials (original) (raw)
Related papers
Evaluation of MEMS materials of construction for implantable medical devices
Biomaterials, 2002
Medical devices based on microelectro-mechanical systems (MEMS) platforms are currently being proposed for a wide variety of implantable applications. However, biocompatibility data for typical MEMS materials of construction and processing, obtained from standard tests currently recognized by regulatory agencies, has not been published. Likewise, the effects of common sterilization techniques on MEMS material properties have not been reported. Medical device regulatory requirements dictate that materials that are biocompatibility tested be processed and sterilized in a manner equivalent to the final production device. Material, processing, and sterilization method can impact the final result.
Biocompatibility and biofouling of MEMS drug delivery devices
Biomaterials, 2003
The biocompatibility and biofouling of the microfabrication materials for a MEMS drug delivery device have been evaluated. The in vivo inflammatory and wound healing response of MEMS drug delivery component materials, metallic gold, silicon nitride, silicon dioxide, silicon, and SU-8 TM photoresist, were evaluated using the cage implant system. Materials, placed into stainless-steel cages, were implanted subcutaneously in a rodent model. Exudates within the cage were sampled at 4, 7, 14, and 21 days, representative of the stages of the inflammatory response, and leukocyte concentrations (leukocytes/ml) were measured. Overall, the inflammatory responses elicited by these materials were not significantly different than those for the empty cage controls over the duration of the study. The material surface cell density (macrophages or foreign body giant cells, FBGCs), an indicator of in vivo biofouling, was determined by scanning electron microscopy of materials explanted at 4, 7, 14, and 21 days. The adherent cellular density of gold, silicon nitride, silicon dioxide, and SU-8 TM were comparable and statistically less (po0:05) than silicon. These analyses identified the MEMS component materials, gold, silicon nitride, silicon dioxide, SU-8 TM , and silicon as biocompatible, with gold, silicon nitride, silicon dioxide, and SU-8 TM showing reduced biofouling. r (J.M.A. Anderson).
Biocompatibility of Candidate Materials for the Realization of Medical Microdevices
2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006
The propulsion of ferromagnetic micro-carriers in the blood vessels by magnetic gradients generated from a Magnetic Resonance Imaging (MRI) system is of special interest for targeted interventions such as chemotherapy or chemo-embolization. As such, Fe-Co alloys for its highest magnetization saturation, and single crystal Ni-Mn-Ga powder and Terfenol-D for their deformation in magnetic field are evaluated for their biocompatibility. The toxicity of these materials is evaluated with MTT cell viability tests. The tests show that Fe-Co (Permendur and Vacoflux 17) alloys are toxic within 24 hours while the single crystal Ni-Mn-Ga powder becomes toxic after 48 hours. The Terfenol-D, despite its high degradation, has 90% cell viability after 72 hours. These results indicate that such candidate materials to be considered in untethered micro-carriers or devices in the blood vessels, would require, depending upon the time spent in the blood vessels, further processes to be viable for such applications.
Overview of Biocompatible Materials and Their Use in Medicine
Folia Medica
This survey presents a thorough overview of the main types of biomaterials used for the manufacturing of implants. The use of different materials for the creation and refinement of medical devices aims at optimizing their properties and raising the level of safety for the patients. The purpose of the study is to classify the most common bulk materials used in medicine according to their nature, interaction with the host tissues and their function in the organisms. Some important advantages and disadvantages of the different classes of implant materials are considered. In the last few years there is a strong tendency toward the surface modification of biomedical devices. Various trends in processing of the materials are focused on increasing their corrosion resistance, wear resistance, biocompatibility and microbiological properties.
2004
Currently there are very few implanted, microsystems medical devices available for citizens in the EU and worldwide, despite the fact that end user requirements are clearly present. There are various reasons for this, including the fact that most micro-structures, micro-sensors and micro-actuators are not developed for medical applications and there are few materials available for long term implantation in the human body. In December 2003, an EU programme, Healthy Aims, was launched to address these and other issues. This arose from the European microsystems network, NEXUS Medical Devices Group and led to a 26 partner team from 9 countries participating in this ambitious and cross disciplinary project. The range of technologies and target products are as follows: • RF communications suitable for implanting into the human body • Implantable power sources • Biocompatible materials • Micro-electrodes to connect the power source to nerves • Micro-assembly techniques for 3D, flexible structures requiring coating with biomaterials • Sensors and actuators to fit inside the body. These technlogies are being targeted at a range of clincial requirements to meet devices ranging from cochlear and eye implants, to pressure sensors and Functional Electrical Stimulation (FES).
IEEE/ASME Journal of Microelectromechanical Systems, 2009
In this paper, we have fabricated and tested several composite materials with a mesh matrix, which are used as encapsulation materials for a novel implantable movable-microelectrode microelectromechanical-system (MEMS) device. Since movable microelectrodes extend off the edge of the MEMS chip and penetrate the brain, a hermetically sealed encapsulation was not feasible. An encapsulation material is needed to prevent cerebral-spinal-fluid entry that could cause failure of the MEMS device and, at the same time, allow for penetration by the microelectrodes. Testing of potential encapsulation materials included penetration-force measurements, gross-leak testing, maximum-pressure testing, and biocompatibility testing. Penetration-force tests showed that untreated mesh matrices and silicone-gel-mesh composites required the least amount of force to penetrate for both nylon 6,6 and polypropylene meshes. The silicone-gel-, poly(dimethylsiloxane)-, polyimide-, and fluoroacrylate-mesh composites with the nylon-mesh matrix were all able to withstand pressures above the normal intracranial pressures. Fourier-transform infrared-spectroscopy analysis and visual inspection of the implanted devices encapsulated by the silicone-gel-mesh composite showed that there was no fluid or debris entry at two and four weeks postimplantation. We conclude that a composite of nylon and silicone-gel meshes will meet the needs of the new generation of implantable devices that require nonhermetic encapsulation.
Biocompatibility Testing for Implants: A Novel Tool for Selection and Characterization
Materials
This review article dives into the complex world of biocompatibility testing: chemical, mechanical, and biological characterization, including many elements of biocompatibility, such as definitions, descriptive examples, and the practical settings. The focus extends to evaluating standard documents obtained from reliable organizations; with a particular focus on open-source information, including FDA-USA, ISO 10933 series, and TÜV SÜD. We found a significant gap in this field: biomaterial scientists and those involved in the realm of medical device development in general, and implants in particular, lack access to a tool that reorganizes the process of selecting the appropriate biocompatibility test for the implant being examined. This work progressed through two key phases that aimed to provide a solution to this gap. A straightforward “yes or no” flowchart was initially developed to guide biocompatibility testing decisions based on the previously accumulated information. Subsequen...
An in vivo biocompatibility assessment of MEMS materials for spinal fusion monitoring
2003
The site-speci®c biocompatibility of silicon chips and commercially available silicon pressure sensor die were evaluated after implantation in caprine (goat) spine. Surgical procedures were developed to insert silicon chips into the nucleus pulposus regions of the lumbar discs and pressure sensors into autologous bone grafts for cervical spine fusion. After a six-month implantation period, the animal was sacri®ced and the spinal segments were meticulously harvested and analyzed for local tissue response via gross examination and histological techniques. Gross examination of cervical and lumbar spinal segments after harvest and dissection did not reveal any visible signs of adverse reactions to the MEMS materials. Furthermore, the surrounding tissues and musculature for both spinal regions were devoid of necrosis. Histological analysis of compromised spinal segments did not reveal evidence of any adverse foreign body response by the caprine spinal tissue to the implanted MEMS materials. These preliminary results support the further development of a spinal fusion monitoring system based on implantable MEMS sensors.
A BioMEMS Review: MEMS Technology for Physiologically Integrated Devices
Proceedings of the IEEE, 2004
MEMS devices are manufactured using similar microfabrication techniques as those used to create integrated circuits. They often, however, have moving components that allow physical or analytical functions to be performed by the device. Although MEMS can be aseptically fabricated and hermetically sealed, biocompatibility of the component materials is a key issue for MEMS used in vivo. Interest in MEMS for biological applications (BioMEMS) is growing rapidly, with opportunities in areas such as biosensors, pacemakers, immunoisolation capsules, and drug delivery. The key to many of these applications lies in the leveraging of features unique to MEMS (for example, analyte sensitivity, electrical responsiveness, temporal control, and feature sizes similar to cells and organelles) for maximum impact. In this paper, we focus on how the biological integration of MEMS and other implantable devices can be improved through the application of microfabrication technology and concepts. Innovative approaches for improved physical and chemical integration of systems with the body are reviewed. An untapped potential for MEMS may lie in the area of nervous and endocrine system actuation, whereby the ability of MEMS to deliver potent drugs or hormones, combined with their precise temporal control, may provide new treatments for disorders of these systems.