Biomedical engineering, also known as bioengineering, is the application of engineering principles to the study of medical and biological problems. The goal of biomedical engineering is to use electrical, chemical, and mechanical engineering principles to conduct studies and develop tools that can aid in the biomedical care of patients.
In 1997, the National Institutes of Health issued the following expansive definition of biomedical engineering/bioengineering: "Bioengineering integrates physical, chemical, or mathematical sciences and engineering principles for the study of biology, medicine, behavior, or health. It advances fundamental concepts, creates knowledge from the molecular to the organ systems levels, and develops innovative biologics, materials, implants, devices, and informatics approaches for the prevention, diagnosis, and treatment of disease, for patient rehabilitation, and for improving health."
Biomedical engineering can trace its history to as far back as a hundred years ago, when the first x-ray machines and electrocardiographs dramatically illustrated how technology could be applied towards the diagnosis of disease. Today, the field of biomedical engineering is in full flower, propelled by the momentum of the post-World War II technology boom and the latest molecular, genetic, and computational developments. Having gone beyond its roots in imaging and instrumentation, biomedical engineering now encompasses at least 13 specialties, according to the 2000 edition of The Biomedical Engineering Handbook.
These specialties include
Biomechanics is the application of classical mechanics (the study of how objects move in response to forces placed on them) to biomedical problems. Classical mechanics provides general principles for understanding (for example) how fluids move, how objects become deformed under various forces, and how levers and forces move objects. Biomechanics uses these principles to understand how blood moves throughout the body, how injuries affect the shape and mechanics of body parts, and the mechanics of body movement (e.g. how an arm is lifted, or how a person walks). Biomechanics has contributed to an understanding of the mechanical function of the bones, cartilage, and soft tissue in the musculoskeletal system, as well as an understanding of other major organ systems, such as the heart, lungs, and blood vessels. Some of the technologies coming from biomechanics include artificial hearts and heart valves, and artificial joints such as prosthetic hip and knee replacements. These types of technologies have spawned another specialty in biomedical engineering, prosthetic devices and artificial organs. Another closely affiliated specialty is transport phenomena. This subfield concerns itself with the processes of fluid flow and heat transfer in biological systems.
Biomaterials are living and artificial materials that can be used in implantation. Whereas biomechanics focuses on the mechanical design of an implant, biomaterials science focuses on the body's biochemical interactions with the material from which an implant is made. A biomaterial for an implant should be chemically inert, non-toxic, and non-carcinogenic. It should also be resilient enough to endure a lifetime of chemical and mechanical forces. Biomedical engineers in the specialty of biomaterials test and study materials possibly suited for implantation. Biomaterials science has contributed to the use and understanding of currently used implant materials, such as ceramics, polymers, metal alloys, and composite materials. Biomaterials science is also leading research into the use of living tissue as implant material with the goal of minimizing implant rejection and simulating the body's original biomechanical environment.
Biomedical instrumentation, or bioinstrumentation, uses mechanical, electrical, and optical principles and systems to monitor the body's physiologic status. Many of the physiologic changes that occur in the body are mediated by electrical signals. Different ions (charged elements or molecules) are allowed to flow into and out of cells at different times, depending on cellular and systemic demands. Biomedical instrumentation attempts to infer aspects of the body's physiologic state by measuring and interpreting these electrical signals. Optical systems are used to measure the variable of interest indirectly; for example, because hemoglobin—the molecule that carries oxygen in the blood—changes its light absorptiveness according to whether it is attached to oxygen, changes in the oxygenation of blood can be inferred from the optical properties of blood and tissue.
The specialty of biosensors focuses on the development and instrumentation of measurement systems. Technologies emerging from biomedical instrumentation generally, and biosensors specifically, include electrocardiographs (ECGs) and pulse oximeters that measure blood oxygenation. The associated specialty of medical and biologic analysis seeks to refine current understanding of the biomedical signals received by the instruments. It attempts to discern and amplify the signals of interest while diminishing noise and unrelated signals. In addition to biomedical measurement, the specialty of biomedical instrumentation includes the development of devices to control and guide biomedical processes through mechanical or electrical means, e.g., cardiac pacemakers and respirators.
Medical imaging uses energy phenomena and physics principles, in conjunction with high-speed data processing, to produce images of the body that reflect its anatomic structure and physiologic function. Developments in medical imaging include x-ray applications (mammography, angiography), ultrasound, computer tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron emission tomography (PET). Each of these technologies is based on exploiting an understanding of electromagnetic or sound energy patterns to provide images of not readily observable aspects of body structure and function.
Physiologic modeling, simulation, and control—also known as systems physiology—attempts to provide formal quantitative models of the various systems of the body, from micro-level systems (at the level of the cell) to macro-level systems (at the level of large organ systems and full-body interactions). Using experimental data and mathematical models, system physiology relies on computer simulation to describe and understand human physiology. These models provide a basis for thinking about how the body functions in an integrated way. Systems physiology is the source of such models as cardiovascular models, respiratory models, neural network models, and biochemical metabolic models.
Biotechnology, also known as cellular, tissue, and genetic engineering, is the study of how biological materials can be modified at a micro-level for useful ends. Biotechnology studies the biochemistry and physics of cells to develop beneficial interventions and biomedical research and diagnostic tools. A sprawling specialty, biotechnology developments have included the development of new diagnostic tests for diseases, the invention of miniature devices that can deliver therapeutic drugs to specific sites, and the production of synthetic vaccines and therapeutic proteins.
Rehabilitation engineering focuses on developing tools for cognitive and physical rehabilitation. Specifically, rehabilitation engineering is concerned with designing technologies that assist mobility and communication. These include the development of rehabilitation prosthetics, the design of living space modifications, the development of transportation alternatives, and the design of hardware and software to aid in communication and cognitive rehabilitation.
Clinical engineering focuses on how the latest biomedical technologies are used in a clinical setting. Aspects of this specialty include the adaptation of biomedical technologies to the needs of the hospital and clinicians, the management of medical instrumentation and equipment, and the purchase and use of current biomedical technologies. An important aspect of clinical engineering is the interface between the medical instrumentation and the clinical software that records data of interest to the hospital. Patient safety and progress are also important aspects of clinical engineering.
Medical informatics is the study of how information is used and disseminated in health care settings. Medical informatics includes the study of health information systems, computer networks in clinical settings, and clinical decision systems. Tools used in medical informatics include neural network models, artificial intelligence models, expert systems, and patient records and archives.