bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk Management for Medical Devices
Authors: Ciarkowski Arthur
Published: April 2006

This article discusses basic concepts of risk management and regulation of medical devices. Risk management is a procedure to reduce the risks involved with a medical device whereas the regulation of medical devices is a public health tool to assure the safety and effectiveness of devices introduced into the market place. Both risk management and regulation are interrelated and take place throughout the entire life cycle of the device, from design through maintenance and obsolescence. As the risks associated with the use of a medical device may vary with the environment where they are used, (e.g., hospital, clinical, home), the risks must be identified and acceptance criteria established to assure that the device perform safely and effectively in its intended environment.
Medical Robotics in Surgery
Authors: Cenk Çavuşoğlu M.
Published: April 2006

This article provides an overview of medical robotic systems and technologies. After introduction of the basic concepts of medical robotics, and introducing a classification of medical robotic systems based on the operator interaction modality, the article discusses the general application areas of robotics technology in medical applications. The presentation is concluded with a discussion on the major research challenges in the area.
Microwave Imaging
Authors: Hinrikus Hiie , Riipulk Jevgeni
Published: April 2006

The overview of applications of microwaves in medical diagnostics is presented. The advantages and disadvantages of passive and active microwave imaging systems, radiometry, tomography, and the confocal radar technique, are analyzed. The limited spatial resolution as well as difficulties in image reconstruction and interpretation of the results do not allow microwave imaging to be successful in competition with technologies for traditional medical imaging. However, microwave imaging provides higher sensitivity with respect to physical or physiological factors of clinical interest, such as temperature, water content, blood‐flow rate, and vascularization/angiogenesis. The data achieved by microwave technology may be possible to relate to the biology of physiological processes, especially in the brain and heart; infections; hyperplasia; and cancer.

The potential advantages of active microwave imaging arise mainly from the high contrast of electrical properties between normal and malignant human breast tissues. Active microwave imaging for the detection of breast tumors is an emerging technique to complement existing x‐ray mammography. The nonionizing microwave radiation does not cause changes on an atomic and a molecular level and is much less harmful for biological tissues than ionizing radiation. A short historical overview about microwave radiometry and tomography is done. The theoretical background of radiometric measurements as well as a short description of different methods and instrumentation developed for data visualization and image reconstruction are presented.
Molecular Electronics
Authors: Rinaldi Ross , Maruccio Giuseppe
Published: April 2006

Moore's Law, the 1965 prediction by Intel co‐founder Gordon Moore that manufacturers would double the number of transistors on a chip every 18 months, has been fulfilled for four decades by the semiconductor industry. But the latest edition of the annual International Technology Roadmap for Semiconductors—a joint effort of semiconductor industry associations in Europe, Japan, Korea, Taiwan, and the United States—lists reasons for thinking that this may soon change. The Roadmap explores “technology nodes”—advances needed to keep shrinking the so‐called DRAM half‐pitch, half the spacing between cells in memory chips. Currently, the industry is moving to a DRAM half‐pitch of 120 nanometers. The Roadmap forecasts that researchers must lower that figure to 35 nanometers by 2014, simply to continue doubling the number of transistors.

In various laboratories worldwide, minimum features sizes that are a factor of 10 smaller (or more) than the 120‐nm node have been demonstrated. However the SIA (Semiconductor Industry Association) Roadmap projects that even though the miniaturization trend will continue for another 15 to 20 years, it is becoming increasingly difficult to continue to down‐scale because of real physical limitations including size of atoms, wavelengths of radiation used for lithography, interconnect scheme. etc.

One of the potential roadblocks to continue the scaling beyond the 50‐nm node is the molecular and biomolecular electronics. In this article we report on fundamental concepts and recent advances in the field of molecular electronics.
Electrodiagnosis in Neuromuscular Disorders
Authors: van Alfen Nens , Zwarts Machiel J
Published: April 2006

This article will deal with the electrodiagnostic assessment of the various neuromuscular disorders. For clarity, they will broadly be divided in three major groups: neurogenic disorders affecting anterior horn cells, ganglia, roots, plexuses, or nerves; myopathies; and neuromuscular junction disorders. The mainstay of the diagnostic tools used relies on electroneurography (nerve conduction studies) and electromyography (needle EMG) techniques, commonly referred to as EMG. A short introduction to nerve conduction studies is given in the second section. For an in‐depth discussion of the various needle EMG techniques, the authors refer the reader to the other articles in this section.
Neural Networks
Authors: Cohen Maurice E.
Published: April 2006

The first artificial neural network was designed in the late 1950s, not long after the development of the first commercial computers. The concept behind neural networks is to use structures of the biological nervous system to develop computer‐based decision‐making tools. The basic functional structure of the neuron was used, including multiple inputs that are combined to produce an output if a predetermined threshold value is achieved. In addition, the parallel nature of the biological nervous system was included in the design. Although the early networks were limited in ability and handicapped by the computers of the time in terms of memory and processing speed, subsequent generations of neural networks have been used to develop robust learning systems based on both supervised and unsupervised learning techniques that have been applied to decision making in biomedicine. These applications are broad based, including clinical decision making, bioinformatics, signal analysis, and image processing.
Neural Control of Assistive Technology
Authors: Taylor Dawn
Published: April 2006

For severely paralyzed individuals, controlling various assistive devices is rapidly becoming a reality. Direct neural control requires tapping into a person's intended actions either directly by decoding brain activity or indirectly by tapping into remaining peripheral nerves or muscles to deduce the desired movements of the person. These neural command signals can be used to drive a wide range of assistive technologies including computer‐based communication programs and environmental controls, assistive robots, and even Functional electrical stimulation (FES) systems designed to restore movement to paralyzed limbs. Both field potentials, such as electroencephalograms (EEGs), and multiunit activity (i.e., action potentials detected from many individual neurons via intracortical microelectrodes) have been used for direct brain control of various devices. Field potentials can be measured noninvasively via large scalp electrodes or invasively via implanted electrode (e.g., imbedded in the skull, placed on the brain surface). The firing patterns of individual neurons as well as the power spectra of recorded field potentials naturally have characteristic changes that accompany attempted or imagined movements. These native movement‐related patterns in the brain signals can be decoded in real‐time and used to command an assistive device. However, with practice, subjects can learn to modulate their recorded brain activity in new ways that can potentially convey a desired device command more effectively than by using the naturally occurring signals alone. This ability to retrain the brain to produce more reliable assistive device commands has been successfully demonstrated with both field potentials and multiunit activity.
Neuromuscular Stimulation
Authors: Grill Warren M.
Published: April 2006

This contribution describes electrical activation of the neuromuscular system with electrodes positioned in or on skeletal muscle. The mechanisms of neuromuscular stimulation are described, with reference to transmission at the neuromuscular junction, to illustrate that it is the motor nerve, rather than the muscle, that is stimulated. The two methods to modulate muscle force, recruitment and rate modulation, are reviewed with reference to their basis in the properties of the neuromuscular system including the force‐frequency relationship of skeletal muscle and the strength‐duration, current‐distance, and current‐diameter relationships for excitation of motor nerve fibers. The elements that impact the shape of the input‐output (recruitment) curve of muscle force as a function of stimulation intensity are presented, including a description of position‐dependent recruitment. In addition, the biomechanical impacts on motor output including the length‐tension properties of skeletal muscle and the transformation of muscle force to joint moment are reviewed. This contribution serves as a comprehensive review of the fundamental aspects of neuromuscular stimulation.
Neuromuscular Systems
Authors: Murray-Smith David J.
Published: April 2006

The biological systems involved in the regulation of posture and control of movement are highly complex and have attracted much attention from biomedical engineers and neurophysiologists. As well as offering possibilities for the treatment of neuromuscular diseases, improved understanding of these systems is important for the management of patients who have suffered strokes or spinal injuries. Control theory provides a useful framework for analysis of neuromuscular systems and mathematical modeling and computer simulation techniques used for engineering systems analysis have proved to be of considerable value in this field. Neuromuscular systems are also of considerable interest to those involved in robotics research and biologically‐inspired robots that have features similar to those of the neuromuscular system are becoming increasingly important. Techniques applied in biomimetic robots are starting to influence the currently accepted theories about the hierarchical structure of the neuromuscular system.
NMR Imaging
Authors: Moratal David , Brummer Marijn E. , Martí-Bonmatí Luis , Vallés-Lluch Ana
Published: April 2006

In 1946, the phenomenon of nuclear magnetic resonance (NMR) was first observed independently by Felix Bloch and Edward Purcell. NMR is a phenomenon exhibited by atoms with an odd number of protons or neutrons which possess nuclear spin angular momentum. In the classical description the phenomenon can be described as spinning charged spheres which produce a small magnetic moment. Developments in NMR over the decades that followed, including the spin echo and different RF pulse sequences, led to widespread use of NMR spectroscopy, a method of analyzing the composition of chemical samples. In 1970, Raymond Damadian discovered the basis for using NMR as a tool for in‐vivo cancer diagnosis. In 1973, Paul Lauterbur proposed the use of gradient magnetic fields for spatial encoding of NMR signals to form the first magnetic resonance images. Magnetic resonance imaging (MRI) has since developed rapidly into a widely used clinical imaging modality, and is now used to image virtually every part of the body in clinical practice. MRI has the important advantage over X‐ray imaging modalities that it does not use ionizing radiation. MRI also allows arbitrary selection of the scan plane and true three‐dimensional imaging. Unlike any other medical imaging modalities, image contrast in MRI is based on multiple physical parameters, resulting in the unique ability to generate excellent soft‐tissue contrast that can be tailored for specific applications.
Nonionizing Radiation
Authors: Wood Andrew
Published: April 2006

Nonionizing radiation (NIR) refers to that part of the electromagnetic spectrum with wavelength greater than approximately 100 nm. It is customary to include static electric and magnetic fields under the heading of NIR, and some include ultrasound. When compared with ionizing radiation, there is a perception that NIR is intrinsically less dangerous (because it does notionize), so that the need for legislative control is less compelling. It should be emphasized that all forms of NIR, if present at a sufficiently high intensity, have the capacity to cause serious injury. It is perhaps fortunate that technologies employing NIR have developed in such a way that instances of serious injury are relatively rare and fatality virtually zero. The accepted hazards of most forms of NIR occur within a short time of exposure. The exception to this is ultraviolet radiation (UVR), particularly solar UVR , in which risks of skin cancer and cataract have a stochastic nature and the diseases occur several years after exposure. The perception among sections of the wider community is that all forms of radiation, including NIR, can lead to disease in the long term, despite a lack of consistent evidence. This article reviews the nature of interactions of NIR with biological tissue, explains the rationale behind present‐day exposure limits, and explores some uncertainties that have led to the “Precautionary Principle” being invoked. It also briefly reviews some properties of NIR that have led to its use in diagnosis and therapy.
Pattern Recognition
Authors: Polikar Robi
Published: April 2006

Pattern recognition is concerned with making automated classification, identification, or intelligent decisions about an unknown system or entity, through analysis of data obtained from such entities or systems. This article provides a comprehensive overview for designing a complete pattern recognition system, by explaining individual components that are cascaded to make up the entire system. Each component processes the available data to prepare it for the next component, starting with preprocessing and conditioning the data, extracting relevant features of the data, choosing the most informative features, choosing a classification algorithm to model the data, training the classification system using a suitable learning algorithm, and finally, an evaluation procedure to estimate the true performance of the overall system. Procedures and algorithms that are most commonly used for each step is explained in detail, followed by a survey of more recent and developing areas. Some of the prominent applications of pattern recognition within and outside of biomedical engineering are also provided as a small but representative sample of a vast array of such applications that benefit from pattern recognition.
Microvessel Permeability
Authors: Fu Bingmei M.
Published: April 2006

Microvessel permeability is a quantitative measure of how permeable the microvessel wall is to all kinds of substances including water, solutes, and cells. Important and recent progresses in microvessel permeability and its regulation are presented and discussed. Although microvessel permeability is a classic problem that has been investigated for more than 50 years, the fundamental question related to structure‐function of microvessel walls and properties of cells forming the walls still remains unclear. Employing mathematical models for more accurate interpretations and predictions, new techniques involving fluorescence, atomic force and electron microscopy, and new developments in molecular biology and biochemistry will lead to more fascinating discoveries in this field.
Blood Substitutes
Authors: Sakai Hiromi , Tsuchida Eishun
Published: April 2006

Blood transfusion systems have contributed considerably to human health and welfare. Nevertheless, numerous problems remain, such as infection of hepatitis virus and HIV, blood type mismatching, immunological response, short shelf life, and costs. Blood substitutes have been under development for decades to overcome those problems. Some substitutes for plasma components are already established, such as plasma expanders, electrolytes, and recombinant coagulant factors. Herein, we specifically address the research and development of substitutes for the function of red blood cells (artificial oxygen carriers, or oxygen infusions) such as chemically modified Hbs, encapsulated Hbs, synthetic heme derivatives, and perfluorochemicals. Unexpected side effects hindered further development of the early artificial oxygen carriers and indicated the physiological significance of the structure of red blood cells. Well‐designed and selected artificial oxygen carriers that meet requisite criteria will be eventually realized. They will provide remarkable innovation in conventional medical treatments.
Neural Networks: Applications in Biomedical Engineering
Authors: Najarian Kayvan , Darvish Alireza
Published: April 2006

This paper provides a brief survey of artificial neural networks and their applications. The paper also describes the structure and the training algorithms of some of the most commonly used neural networks and their applications. Neural structures covered in this paper include multilayer sigmoid neural networks, Hopfield networks, radial basis functions, and self‐organizing maps. Finally, some specific applications of neural networks in different fields of biomedical engineering are described.
Respiratory‐Related Evoked Potentials
Authors: Andrew Daubenspeck J.
Published: April 2006

Respiratory evoked potentials (RREP s) provide a window into the nature of sensory afferent activity available for respiratory control and the perception of respiratory events. Because RREP s reflect the mass of stimulated activity, the view offered is comprehensive beyond anything possible from individual nerve recordings. Although there are many challenges to the interpretation of RREP s, they offer a unique, noninvasive tool for evaluation of respiratory sensation in intact organisms.
Respiratory Sinus Arrhythmia
Authors: Patwardhan Abhijit
Published: April 2006

It has been long recognized that the period of the heart, that is, the interval between two heartbeats, changes in rhythm with respiration. Change in heart periods that is synchronous with respiration is called respiratory sinus arrhythmia (RSA). In a healthy person, the heart speeds up during inspiration and slows down during expiration. RSA is perhaps one of the more widely investigated phenomenon in the field of integrative physiology. The objective in this chapter is to introduce the reader to RSA, and it is organized to address the following issues: What is RSA? What are the prominent empirical features of RSA? What are the issues related to measurement of RSA? And, what causes RSA? There is considerable evidence that suggests that RSA is a result of autonomic neural activity. Quantified RSA is simple to measure, yet a powerful index that provides an insight about autonomic nervous activity that governs cardiac function. Given the widely hypothesized dominant role of neural function in cardiac health, this index, identified many centuries ago, continues to be the focus of modern scientific exploration.
Risk Management
Authors: Bartoo Grace
Published: April 2006

Biomedical engineers strive to develop devices that are both effective and safe. Risk management is an essential skill that all medical device developers should understand and use aggressively to minimize any potential harm to patients and operators of the device. Risk management is the systematic application of policies, procedures, and practices to the tasks of identifying, analyzing, controlling, and monitoring risks associated with a device. Multiple techniques exist that can be used to conduct risk analyses and estimation such as hazard analysis (HA), failure modes and effects analysis (FMEA), and fault tree analysis (FTA). After risk analyses and evaluation for acceptability is conducted, risk control measures are selected and implemented. These risk control measures should be verified for effectiveness. Analysis of the remaining risk after implementation of the risk control measures should be conducted and the overall acceptability of the residual risk determined. Clearly, the benefits of the device should outweigh the residual risks in order to move forward with the development of the device.

An international standard, ISO 14971:2000, exists that provides a straightforward description of how to establish an effective risk management process. This chapter provides an overview of the risk management process described in that standard and the documentation that is required. Application of risk management throughout the product development process will help the company to anticipate failures, make safer products, and minimize liability exposure.
Sensory Aids
Authors: Seelman Katherine , Brabyn J. , Ortmann A. , Palmer C.
Published: April 2006

Individuals with complete or partial loss of vision or hearing have a reduction of sensory input that affects their interaction with the environment. Approximately 3.5–6 million people have vision loss and 8 million have hearing loss. Different diseases and pathologies give rise to different forms of functional limitations. Individuals with loss of vision or hearing improve function through the use of sensory aids as a supplement to or a substitute for seeing or hearing in order to participate in society and to perform activities of daily living. Sensory aids range from individual medical and assistive devices to technologies that enhance the accessibility of the natural, built, transportation, and information/communications environments. Some individuals with vision loss may also use readers and those with hearing loss may use sign language interpreters to access information. Research and development, commercialization, and public support for purchase of individual aids and change in environmental accessibility have been stimulated or mandated by public laws and regulations such as those related to the Americans with Disabilities Act of 1990. Using a universal design strategy, some aids are designed into mainstream products and environments, as is the case of the decoder chip that produces captioning on the screen of a television set. Universally designed products have spilled over from special interest markets such as deaf and hard of hearing users of captioning to mainstream markets in locations with loud background noise such as health clubs and bars. Although the history of the development of sensory aids is hundreds of years old, opportunities and challenges have proliferated with the development of computing and communications technology. Throughout history, individuals with vision loss and individuals with hearing loss have challenged engineers, and clinicians, and architects with their different medical, functional, and environmental problems.
Simulation Languages
Authors: Roa Laura , Prado Manuel
Published: April 2006

A computer simulation model is an abstract entity that describes the dynamics behavior of a target system. It can be designed according to different modeling methodologies and implemented in a computer by means of a programming language. Many specific programming languages have been developed to facilitate this implementation. These are formally designated as modeling languages. The execution of a computer model is referred to as the simulation or experimental phase. Some modern software simulation environments provide extensions to modeling languages that simplify common tasks such as parameter identification, sensitivity analysis, validation, and even the connection to external data sources and other software programs. Accordingly, specific languages used to describe, implement, and even design the subsequent experiments are called modeling and simulation languages or, simply, simulation languages. We use both modeling language and simulation language as synonymous terms throughout the text despite the fact that they are not formally the same.

The high number of software environments for modeling and simulation and their dependence on the domain of the system to be modeled makes unsuccessful the review of the state of the art in this field by means of an approach based on the description of their major technical features. This work follows a more fruitful approach, which is the description of the major methodologies and technologies that underlie the simulation languages and software environments. With this objective, the chapter begins with a brief review of the most important milestones in modeling and simulation methodologies, which is followed by a formal description of the current ones. That section is followed by another one devoted to several important mathematical subjects related to language causality, which is the base of some of the major cutting edge advances in modeling languages. Several representative languages and software environments founded on the different methodologies analyzed are cited afterwards. The chapter ends with a section dedicated to review biomedical engineering applications of computer simulation models and current trends in the modeling and simulation field.
Sleep Apnea: Detection and Classification of Infant Patterns
Authors: Sermet Anagun A.
Published: April 2006

Apnea is defined as a period in which an infant stops breathing. When the apnea period is greater than a critical period, serious damage in the infant's brain may result from lack of oxygen. In order to prevent this serious event, a need exists to find a reliable way to detect apnea and to determine causes of apnea. For that reason, sensors exclusively designed for research purposes, and especially manufactured apnea monitors with built‐in sensor, used at homes and pediatrics intensive care units in hospitals have been employed. As a result of the limitations and weaknesses of commercially available apnea monitors, in recent years, artificial intelligence techniques, especially neural networks have gained attention in terms of finding a reliable and alternative way to analyze respiration signals to determine if apnea exists and, if so, the length of apnea. In this study, an overview of apnea, difficulties in apnea monitoring, and elementary information for data acquisition and neural networks are given; a multi‐layered neural network for apnea recognition is designed; and applicability of the designed neural network trained with a set of respiration patterns obtained from infants who have apneic episodes is discussed in terms of detecting and classifying apnea patterns.
Sleep Laboratory
Authors: Penzel Thomas
Published: April 2006

Sleep research has evolved to sleep medicine over the past 20 years. Sleep laboratories are now established in many places in order to diagnose and treat sleep disorders. The most prevalent sleep disorder is insomnia, but this is rarely investigated in a sleep laboratory. Second most prevalent are sleep‐related breathing disorders, with obstructive sleep apnea as the best known disorder. A sleep laboratory provides methods for diagnosing this and other sleep disorders with the use of cardiorespiratory polysomnography. In addition, daytime testing of sleepiness is used to check the effect of treatment on daytime function and performance. Cardiorespiratory polysomnography uses digital equipment with defined requirements on sleep signals, respiratory, movement, and cardiovascular signals. Computer‐based polysomnography tries to support the sleep expert with automated analysis of sleep, respiration, and movement. These methods did not succeed in replacing visual evaluation methods until now. Currently, the definitions for sleep stages are being reassessed. The revised definitions may improve the basis for the development of analysis algorithms, which can then achieve a better validity compared with expert evaluation. In addition, new developments in the field of sensor technology make use of miniaturization and noninvasive signal assessment in order to improve patient sleep comfort during the sleep study.
Software Agents
Authors: Stiglic Gregor , Verlic Mateja , Kokol Peter
Published: April 2006

Software engineering theory, practice, and applications germane to biomedical engineering are presented.
Stenosis and Thrombosis
Authors: Walsh Peter , McLachlan Craig
Published: April 2006

Vascular stenosis is defined as a narrowing or constriction to the body or opening of a vessel conduit. Stenosis and thrombus formations are the result of vascular injury and inflammation due to vascular cell dysfunction, resulting in any of the following pathological or healing injury responses: an initial coagulation/thrombus (blood clot) on the vascular inner wall to promote healing or further injury and inflammation; vascular smooth muscle cell proliferation and migration into the blood vessel lumen promoting stenosis following an initial disruption to the endothelium; atherosclerosis in which both early thrombus and smooth muscle cell proliferation and migration participate; and atherothrombosis that interacts with a mature atherosclerotic plaque to form a blood clot on the surface of the plaque resulting in further stenosis or possible emboli. Changes in vascular function are governed by the dynamic mechanical environment consisting of shear stress, wall stresses, and pressure imposed on the cells within the vascular wall as a result of blood flow. Endothelial cells in the intima and the smooth muscle cells within the vessel media are stimulated with these mechanical stresses that alter their behavior. Atherosclerosis and other causes of stenosis develop at localized regions within the vasculature that correlate to localized mechanical conditions. Disease typically occurs at arterial sites where endothelial cells would be exposed to low and oscillatory shear stress. Localized variations in the inner to outer wall stresses also appear to be related to disease‐formation. This chapter reviews studies integrating biology with vascular mechanical events that explain the current theories on stenosis and thrombosis.
Stress
Authors: Debes Jack C. , Wickham Lori L.
Published: April 2006

The word stress has many different meanings depending on the context in which it is used. However, in mechanics, it has a precise meaning. Stress is a measure of force intensity in a material and may be described in terms of a force per unit area. It is important to differentiate stress from strain, which is a measure of the deformation of a material resulting from stress. Stress and strain are separate, but physically coupled entities, which are related mathematically by a constitutive equation.
Temperature Sensors
Authors: Tamura Toshiyo , Tatsuo Togawa
Published: April 2006

Integrated circulatory (IC) sensors are becoming popular to monitor body temperatures. Traditional temperature techniques, such as thermocouples, thermistors, and RDTs are being displaced by silicon sensors with their ease of integration and use. Many traditional sensors types are inherently nonlinear and require signal conditioning to accurately convert temperature into an electrically measurable quantity such as voltage or current. The IC sensors as well as traditional sensors are briefly reviewed.
Thermal Conductivity Measurement of Biomaterials
Authors: Baish James
Published: April 2006

This chapter reviews the theory and practice of measuring the thermal conductivity of biomaterials. Particular attention is given to the special considerations that accompany measurements of soft tissues
in situ
. Many of these techniques are somewhat invasive in their use of small implanted thermistor probes. Others use heat sources and temperature sensors that can operate with only surface contact or with no contact whatsoever. The relative merits of the various techniques are reviewed. The relationship of the intrinsic thermal conductivity to apparent enhancements to the conductivity that develop because of blood perfusion is also presented.
Tissue Mechanics
Authors: Michael Lee J.
Published: April 2006

Tissue mechanics is the field of endeavour that seeks to understand and describe the links between structure and mechanical function in the soft and hard tissues of the human body. Much of the research work has been done in the connective tissues of the body (e.g., bone, tendons, cartilage, arteries, and skin) where mechanical demands are greatest; however, all tissues have mechanical features of interest. Approaches to the field have included: (1) use of structural anatomy as a means to understanding natural design, (2) mechanical engineering analysis of structures based on continuum mechanics, and (3) materials science study of detailed links between structure and function. As natural tissues are all composite materials, understanding of their mechanical function demands study of the mechanical properties and architectural arrangement of the individual structural components, particularly: strong, stiff collagen fibers; the physiological rubber elastin; hydroxyapatite mineral; and proteoglycan sol/gels. The mechanical features of tissues include marked anisotropy, nonlinear stress‐strain relations, viscoelasticity, preconditioning behavior, and the presence of pre‐stress. Most studies of the mechanical behavior of tissues have been carried out in the laboratory, with samples removed from cadavers or animals, cut or machined to shape, and tested either fresh or after storage. Commercial testing machines based on electromechanical or hydraulic systems are widely used, as are custom‐built apparatus. Testing is also carried out in living animals or patients. In either case, determination of sample geometry or deformations are difficult. Mathematical description of data is an important part of tissue mechanics, as is modeling of 3‐dimensional stress‐strain behavior. Soft tissues require the use of large deformation (finite) elasticity equations. Modeling may either be phenomenological (seeking to describe behavior using model systems that do not reference structure) or may be explicitly based on knowledge of tissue architecture. Phenomenological models have often been based on linear or quasilinear viscoelastic theory derived from previous work on polymer materials. Constitutive equations, particularly those based on development of strain energy density functions, have been widely used as a means to describing tissue behavior under arbitrary loading. In a complementary development, finite element analysis has found wide use for analysis of complex structures. Tissue mechanics is a tool both for: (1) the study of natural structures in health and disease, and (2) technological application, which, in recent years, has included design of surgical replacements and surgical technique, evaluation and design of tissue engineered replacements, and analysis/prevention of injuries caused by automobile accidents, blasts, and other trauma.
Vascular Mechanics
Authors: Moore James E. , Bedoya Julian , Meyer Clark , Moreno Michael R. , Mori Daisuke , Rhabar Elaheh
Published: April 2006

The vascular system provides the crucial task of delivering oxygen and nutrients to all of the body's tissues. The proper functioning of the system is made possible by very specific mechanical characteristics that result from the combination of different materials. Vessel walls contain crucial cellular elements that themselves require nutrients and strongly affect the mechanical performance. Arterial mechanics are important in the formation and progression of a number of diseases. In turn, the mechanical properties are affected by disease development. Research in this field is richly challenging because of the complexity of the mechanics and the interaction with biological function.
Voice Analysis
Authors: Manfredi Claudia
Published: April 2006

Voice analysis measures the frequency of phonation as well as the variation of the voice. Voiced sounds are those created by vibrations of the vocal folds in the larynx. The variation of the voice signal associated with opening and closing of the vocal folds is related to the perception of hoarseness, harshness, and breathiness. Much of the research in voice analysis, from the biomedical point of view, is directed toward diagnostic applications and speech therapy. Defining protocols and reliable objective parameters is of great relevance for physicians. Speech‐language pathologists, otolaryngologists, voice teachers, and singers often use software that can identify the acoustic features of sustained or sung vowels for clinical assessment or vocal training.

To this aim, modeling techniques were developed in order to make voice production tractable from a mathematical point of view. Mechanical and acoustical models are inherently a simplified version of the real physical mechanism, as approximations are introduced in order to describe it. However, from these models, theoretical results can be derived that allow implementation of reliable and efficient voice analysis techniques. The aim with all approaches is the extraction of the main voice parameters (fundamental frequency, formants, voice quality) in the most reliable way.

Advances in real‐time imaging offer the prospect of multimodal analysis through videolaryngoscopy, videokymography, functional magnetic resonance imaging, and other emerging techniques. Links are also being formed to understand the relationship between speech and neurological dysfunction (e.g., epilepsy, autism, schizophrenia, stress, etc.) and the interaction with hearing impairment.
F‐Wave
Authors: Kong Xuan , Gozani Shai
Published: April 2006

F‐waves are recorded responses evoked by antidromic activation of motor neurons. F‐waves play a critical role in the functional evaluation of the peripheral nerve system as well as the central nerve system. Demonstrated clinical diagnostic applications include diabetic neuropathy and lumbosacal radiculopathy. Commonly used F‐wave features are introduced and their clinical application is discussed. A signal processing model for the F‐wave is examined and a framework for automated F‐wave analysis is established. A detailed discussion on using F‐waves for lumbosacral nerve root compression detection is presented. Finally, future biomedical engineering research directions for F‐waves are suggested.
Home Telehealth: Telematics‐Supported Services
Authors: Valero Miguel A. , Arredondo María T.
Published: April 2006

Health care delivery at home, supported at distance by telematics, is a key application domain of telemedicine and e‐health that has been widely analyzed and put into operation along the last decade (1995–2005) both in pilot, research demonstrations, and commercial services. Five key aspects influence home telehealth deployment in clinical routine: population needs linked to health and social expectations; trends in home‐based care policies; availability of affordable technology at residential environments; cost‐effective provision models; and ethic‐legal issues. Telematics development can support communication and information services for health providing that interaction and data transmission requirements of each foreseen residential telehealth service might be clearly defined and accessible both to end users, that is to say, citizens and health professionals. Qualitative and quantitative knowledge or realistic inference of the value of these variables is still a key aspect to extend home telehealth for all.
Surface Electrostimulation Electrodes
Authors: Bajd Tadej
Published: April 2006

Surface stimulation electrodes are predominantly used for therapeutic purposes in training of atrophied muscles and peripheral neuromodulation of pain. Electrode size, polarity of the electrodes, resistance, and distance between the electrodes are important properties of use of surface stimulation electrodes. The theoretical approach to the surface electrodes problem is presented by an equivalent circuit of the electrodes and its interface with the body. Metal surface electrodes, conductive silicon rubber electrodes, conductive adhesive gel electrodes, and transcutaneous electrode arrays are described. The problems common to surface stimulation electrodes, such as possible damage to skin, exciting of pain receptors, inadequate repeatability and poor selectivity of the response, undesired motion of the skin with respect to neuromuscular tissue, and electrode fixation problems, are discussed.
Human Brain Interface: Signal Processing and Machine Learning
Authors: Vesin Jean-Marc , Hoffmann Ulrich , Ebrahimi Touradj
Published: April 2006

The Electroencephalogram (EEG) is a recording of the electrical potentials generated by brain activity on the scalp. It has been used for decades as a non‐invasive tool both in fundamental brain research and in clinical diagnosis. But it is now widely used also in Brain‐Computer Interfaces (BCI) to provide augmentative communication mainly for severely handicapped patients and, prospectively, in the general frame work of human computer interaction. As in any communication system, the input (EEG activity) must be coded (feature extraction) before being sent, and the receiving device (the computer) must map the received data to actions (classication). This article explores the main approaches used in the BCI community for completing these tasks.
Metabolites, NonInvasive Optical Measurements of
Authors: Khalil Omar S.
Published: April 2006

Noninvasive (NI) optical monitoring techniques measure the concentration of analytes in blood or tissue without taking out a sample or without inserting any instrumentation into the human body. Optical biopsy describes NI optical tracking of concentration of molecules in human tissue. Novel tissue optics methods will open new vistas in medical diagnostics and will offer simpler testing modalities compared with current methods. The 600‐nm to 1300‐nm region of the electromagnetic spectrum represents a window where light penetrates deep enough in the tissue to allow performing optical measurements. NI determination of arterial oxygen saturation is used for monitoring postoperative and critical care patients. NI determinations of hemoglobin offer diagnosis of anemia and internal bleeding. Bilirubin measurements were used for monitoring neonates. Monitoring of diabetics is the most important potential advantage for NI optical diagnostics. A NI glucose‐testing device will improve diabetes control through more frequent testing and adjustment of medication. NI optical detection procedures involve irradiating tissue or a vascular region of the body with electromagnetic radiation and measuring the spectral information that results from absorption, scattering, and emission. The concentration of an analyte is determined from the spectral information by comparing the measured spectra with a calibration model. Metabolites affect transmitted and reflected optical signals by affecting light absorption and scattering. Transmission, diffuse reflectance, spatially resolved diffuse reflectance
R
(
r
), frequency domain reflectance, time‐resolved transmission and reflectance, optical coherence tomography (OCT), and Raman and fluorescence measurements were used for the NI determination of metabolites and are discussed.
Temporomandibular Joint Disc
Authors: Allen Kyle D. , Detamore Michael S. , Almarza Alejandro J. , Wong Mark , Athanasiou Kyriacos A.
Published: April 2006

The temporomandibular joint (TMJ) is a ginglymo‐diarthrodial synovial joint. Its principal components are the fossa‐eminence of temporal bone, the mandibular condyle, and a fibrocartilagenous articular disc known as the TMJ disc. TMJ movements are more complex than most synovial joints. The TMJ disc plays a key role in these movements by distributing load, absorbing shock, and lubricating surfaces. The extracellular matrix (ECM) of the TMJ disc is primarily composed of collagen type I, which forms a ring‐like structure around the periphery of the disc and in the anteroposterior direction in the intermediate zone. Glycosaminoglycans, proteoglycans, and elastin fibers also form the ECM. The cell types of the disc include a nonhomogeneous distribution of fibroblasts and chondrocyte‐like cells; these cells serve to maintain the ECM of the TMJ disc. The mechanical properties of the disc are mostly unknown because of large variations between animal models and test methodologies; however, it is believed that the TMJ disc is primarily a tensile tissue. Several disorders, including internal derangements, degenerative diseases, and reparative/osteogenic diseases, are associated with an injured or displaced disc. These disorders affect about 2–4% of the population and greatly reduce the quality of a patient's life, afflicting everyday activities such as eating, talking, and laughing. Treatments for severe temporomandibular dysfunction are available, but alleviation of joint problems without future repercussions is difficult. Biomedical engineering continues to work toward better solutions for temporomandibular dysfunction by developing innovative treatments and fully characterizing the components and diseases of the TMJ.
Ultrasonic Imaging of Carotid Atherosclerosis
Authors: Pattichis Constantinos S. , Christodoulou Christodoulos , Kyriacou Efthyvoulos , Pantziaris Marios , Nicolaides Ardrew , Pattichis Marios S. , Loizou Christos
Published: April 2006

Ultrasound is widely used in vascular imaging because of its ability to visualize, in real‐time, the arterial lumen and wall in a noninvasive and harmless way. Monitoring of the arterial characteristics like the vessel lumen diameter, the intima media thickness of the near and far wall, and the morphology of atherosclerotic plaque are very important in order to assess the severity of atherosclerosis and evaluate its progression. Quantitative image analysis based on despeckle filtering, automated or semiautomated segmentation of the intima media or the atherosclerotic plaque, texture feature extraction and selection, and classification support computer‐aided diagnosis, enabling early diagnosis, disease monitoring, and better treatment. Emerging techniques in vascular imaging include 3‐D imaging, which attempts to provide the physician with a more realistic reconstruction and visualization of the 3‐D structure under investigation, telemedicine and ultrasound video compression, and others. Furthermore, it is hoped that once genes contributing to atherosclerosis have been identified, combined with DNA‐based tests, risk factors and quantitative ultrasound vascular imaging will contribute toward the implementation of the most effective strategy to minimize cardiovascular death.
Substrate Arrays of Microelectrodes for
in vitro
Electrophysiology
Authors: Giugliano M. , Martinoia S.
Published: April 2006

The collective electrical phenomena emerging in a network of interacting neurons represent one of the most advanced and technically challenging research issues in the neurosciences. Under these perspectives, in recent years, experimental neurophysiologists have taken greater advantage of novel tools offered by micro‐ and nano‐fabrication technologies. Such techniques, originally developed for the microelectronic industry, can be employed to build extremely small multisite bidirectional signal probes, either for in
in vitro
or in
in vivo
studies in cellular electrophysiology. As a result, an original research area emerged at the interface between network‐level neuroscience and engineering. In particular, the thin‐film‐based substrate arrays of microtransducers (MEAs) represent an important outcome of this field. This chapter will review the fabrication techniques and the applications with respect to
in vitro
brain tissue slices and cultured dissociated neuronal networks electrophysiology. We mention the alternative and complementary techniques and we report some experimental results. We conclude by underlying the important contributions of the MEAs to the network‐level neurosciences and neuroengineering, and to the design of neuroprosthetic devices.