Bioengineering

Summary

Bioengineering is the field where techniques drawn from engineering are used to find solutions to biological problems. For example, bioengineers may use mechanics principles—knowledge about how to design and construct mechanical objects using the most ideal materials—to create drug delivery systems. They may work on developing efficient ways to irrigate and drain land for growing crops. Alternatively they may be involved in building artificial environments that can support life even in the harsh climate of outer space. A highly interdisciplinary, collaborative field that synthesizes expertise from multiple research areas, bioengineering has had a significant impact on many fields of study, including the health sciences, technology, and agriculture.

Definition and Basic Principles

Bioengineering is an interdisciplinary field of applied science that deals with the application of engineering methods, techniques, design approaches, and fundamental knowledge. This is to solve practical problems in the life sciences, including biology, geology, environmental studies, and agriculture. In many contexts, the term bioengineering is used to refer solely to biomedical engineering. This is the application of engineering principles to medicine, such as in the development of artificial organs or limbs. However, the field of bioengineering has many applications beyond the field of health care. For example, genetically modified crops that are resistant to pests, suits that protect astronauts from the ultra-low pressures in space, and brain-computer interfaces that may allow soldiers to exercise remote control over military vehicles all fall under the wide umbrella of bioengineering.

Each of the subdisciplines within bioengineering relies on different sets of basic engineering principles. Nonetheless, a few fundamental approaches can be said to apply broadly across the entire field. From an engineering perspective, three basic steps are involved in solving any problem: an analysis of how the system in question works, an attempt to synthesize the information gathered from this analysis and generate potential solutions, and finally an attempt to design and test a useful product. Bioengineers apply this three-stage problem-solving process to problems in the life sciences. What is somewhat novel about this approach is that it is a holistic one. In other words, it treats biological entities as systems. This set of parts that work together and forms an integrated whole. This is opposed to viewing individual parts in isolation. For example, to develop an artificial heart, bioengineers need to consider not just the structure of the heart on a cellular or tissue level but also the complex dynamics of the organ's interactions with the rest of the body through the circulatory system and the immune system. They must build a device whose parts can mimic the functionality of a healthy heart and whose materials can be easily integrated into the body without triggering a harmful immune response.

Background and History

Principles of chemical and mechanical engineering have been applied to problems in specific biological systems for centuries. For example, bioengineering applications include the fermentation of alcoholic beverages, the use of artificial limbsdocumented as far back as 500 BCEand the building of heating and cooling systems that regulate human environments.

Bioengineering did not emerge as a formal scientific discipline, however, until the middle of the twentieth century. During this period, scientists became interested in applying new technologies from electronic and mechanical engineering to the life sciences. As the United States, Japan, and Europe began to enter a period of economic recovery and growth following World War II, governments increased funding for bioengineering efforts. The cardiac pacemaker and the defibrillator, both developed during this postwar period, were two of the earliest and most significant inventions to come out of this quickly developing field. In 1966, the Engineers Joint Council Committee on Engineering Interaction with Biology and Medicine first used the term bioengineering. At the same time, academic institutions began to form specialized departments and programs of study to train professionals in the application of engineering principles to biological problems. In the twenty-first century, rapid technological advances continue to produce growth in the field of bioengineering.

How It Works

Because bioengineering is such a large and diverse field, it would be impossible to enumerate all the processes involved in creating the totality of its applications. The following are a few of the most significant examples of the types of technological tools used in bioengineering.

Materials Science

One of the most important areas of bioengineering is the intersection of materials science and biology. Scientists working in this field are charged with developing materials that, although synthetic, are able to successfully interact with living tissues or other natural biological systems without impeding them. As an example, it is vital that biocompatible materials not allow blood platelets to adhere to them and form clots, which can be fatal. Depending on the specific application in question, other properties, such as tensile strength, resistance to wear, and permeability to water, gases, and small biological molecules, are also important. To manipulate these properties to achieve a desired end, engineers must carefully control both the chemical structure and the molecular organization of the materials. For this reason, biocompatible materials are generally made out of some kind of synthetic polymer—substances with simple and extremely regular molecular structures that repeat many times. In addition, additives may be incorporated into the materials, such as inorganic fillers that allow for greater mechanical flexibility or stabilizers and antioxidants that keep the material from becoming degraded over time.

Biochemical Engineering

Since living cells are essentially chemical systems, the tools of chemical engineering are especially applicable to biology. Biochemical engineers study and manipulate the behavior of living cells. Their basic tool for doing this is a fermenter, a large reactor within which chemical processes can be carried out under carefully controlled conditions. For example, the modern production of virtually all antibiotics, such as penicillin and tetracycline, takes place inside a fermenter. A central vessel, sealed tight to prevent contamination and surrounded by jackets filled with coolants to control its temperature, contains propellers that stir around the nutrients, culture ingredients, and catalysts that are associated with the reaction at hand.

Genetic engineering is a subfield of biochemical engineering that is growing increasingly significant. Scientists alter the genetic information in one cell by inserting into it a gene from another organism. To do this, a vector such as a virus or a plasmida small strand of DNAis placed into the cell nucleus and combines with the existing genes to form a new genetic code. The technology that enables scientists to alter the genetic information of an organism is called gene splicing. The new genetic information created by this process is known as recombinant DNA. Genetic engineering can be divided into two types: somatic and germ line. Somatic genetic engineering is a process by which gene splicing is carried out within specific organs or tissues of a fully formed organism. Germ-line genetic engineering is a process by which gene splicing is carried out within sex cells or embryos, causing the recombinant DNA to exist in every cell of the organism as it grows.

Electrical Engineering

Electrical engineering technologies are an essential part of the bioengineering tool kit. In many cases, the bioengineer is required to find a way to convert sensory data into electric signals, and then to produce these electric signals in such a way as to enable them to have a physiological effect on a living organism.

The cochlear implant is an example of one such development. The cochlea is the part of the brain that interprets sounds, and a cochlear implant is designed for people who are almost entirely deaf. A cochlear implant uses electronic devices that capture sounds and relay them to the cochlea. The implant has four parts: a microphone, a tiny computer processor, a radio transmitter, and a receiver, which surgeons implant in the user's skull. The microphone picks up nearby sounds, such as human speech or music emerging from a pair of stereo speakers. Then the processor converts the sounds into digital information that can be sent through a wire to the radio transmitter. The software used by the processor separates sounds into different channels, each representing a range of frequencies. In turn, the radio transmitter translates the digital information into radio signals, which it relays through the skull to the receiver. The receiver then turns the radio signals into electric impulses, which directly stimulate the nerve endings in the cochlea. It is these electric signals that the brain is able to interpret as sounds, allowing even profoundly deaf people to hear.

Another example of how electric signals can be used to direct biological systems can be found in brain-computer interfaces (BCIs). BCIs are direct channels of communication between a computer and the neurons in the human brain. They work because activity in the brain, such as that produced by thoughts or sensory processing, can be detected by bio-instruments designed to record electrophysiological signals. These signals can then be transmitted to a computer and used to generate commands. For example, BCIs allow stroke victims who have lost the use of a limb to regain mobility; a patient's thoughts about movement are transmitted to an external machine, which in turn transmits electric signals that precisely control the movements of a cradle holding his or her paralyzed arm.

Applications and Products

Biomedical Applications

Biomedical engineering is a vast subdiscipline of bioengineering, which itself encompasses multiple fields of interest. The many clinical areas in which applications are being developed by biomedical engineers include medical imaging, cell and tissue engineering, bioinstrumentation, the development of biocompatible materials and devices, biomechanics, and the emerging field of bio-nanotechnology.

Medical imaging applications collect data about patients' bodies and turn that data into useful images that physicians can interpret for diagnostic purposes. For example, ultrasound scans, which map the reflection and reduction in force of sounds as they bounce off an object, are used to monitor the development of fetuses in the wombs of pregnant women. Magnetic resonance imaging (MRI), which measures the response of body tissues to high-frequency radio waves, is often used to detect structural abnormalities in the brain or other body parts.

Cell and tissue engineering is the attempt to exploit the natural characteristics of living cells to regenerate lost or damaged tissue. For example, bioengineers are working on creating viable replacement heart cells for people who have suffered cardiac arrests. They also try to discover ways to regenerate brain cells lost by patients with neurodegenerative disorders such as Alzheimers disease. Genetic engineering is a closely related area of biomedicine in which DNA from a foreign organism is introduced into a cell so as to create a new genetic code with desired characteristics.

Bioinstrumentation is the application of electrical engineering principles to develop machines that can sense and respond to biological or physiological signals. These include portable devices for diabetics that measure and report the level of glucose in their blood. Other examples of bioinstrumentation include electroencephalogram (EEG) machines that continuously monitor brain waves in real time, and electrocardiograph (ECG) machines that perform the same task with heartbeats.

Many biomedical engineers work on developing materials and devices that are biocompatible, meaning that they can replace or come into direct contact with living tissues, perform a biological function, and refrain from triggering an immune system response. Pacemakers, small artificial devices that are implanted within the body and used to stimulate heart muscles to produce steady, reliable contractions, are a good example of a biocompatible device that has emerged from the collaboration of engineers and clinicians.

Biomechanics is the study of how the muscles and skeletal structure of living organisms are affected by and exert mechanical forces. Biomechanics applications include the development of orthoticsbraces or supportssuch as spinal, leg, and foot braces for patients with disabling disorders such as cerebral palsy, multiple sclerosis, or stroke. Prostheses, or artificial limbs, also fall under the field of biomechanics. The sockets, joints, brakes, and pneumatic or hydraulic controls of an artificial leg are manufactured and then combined in a modular fashion, in much the same way as are the parts of an automobile in a factory.

Bio-Nanotechnology

Nanotechnology is a fairly young field of applied science concerned with the manipulation of objects at the nanoscale to produce machinery. A nanometer is about one-thousandth the width of a strand of human hair. Bionanotechnological applications within medicine include microscopic biosensors installed on small chips. These can be specialized to recognize and flag specific proteins or antibodies. They also help physicians conduct extremely fast and inexpensive diagnostic tests. Bioengineers are also developing microelectrodes on a nanoscale. These arrays of tiny electrodes can be implanted into the brain and used to stimulate specific nerve cells to treat movement disorders and other diseases.

Military Applications

Bioengineering applications are making themselves felt as a powerful presence on the front lines of the military. For example, bioengineering students at the University of Virginia designed lighter, more flexible, and stronger bullet-proof body armor using specially created ceramic tiles that are inserted into protective vests. The armor is able to withstand multiple impacts and distributes shock more evenly across the wearer's body. This prevents damaging compression to the chest. Others working in the field are creating sophisticated biosensors that soldiers can use to detect the presence of potential pathogens or biological weapons that have been released into the air.

One of the most significant contributions of bioengineering to the military is in the development of treatments for severe traumas sustained during warfare. For example, stem cell research may one day enable military physicians to regenerate functional tissues such as nerves, bone, cartilage, skin, and muscle—an invaluable tool for helping those who have lost limbs or other body parts as a result of explosives. The United States military was responsible for much of the early research done in creating safe, effective artificial blood substitutes that could be easily stored and relied on to be free of contamination on the battlefield.

Agriculture

Agricultural engineering involves the application of both engineering technologies and knowledge from animal and plant biology to problems in agriculture, such as soil and water conservation, food processing, and animal husbandry. For example, agricultural engineers can help farmers maximize crop yields from a defined area of land. This technique, known as precision farming, involves analyzing the properties of the soildrainage, electrical conductivity, pH [acidity] level, and levels of chemicals such as nitrogenand carefully calibrating the type and amount of seeds, insecticides, and fertilizers to be used.

Farm machinery and implements represent another area of agriculture in which engineering principles have made a big impact. Tractors, harvesters, combines, and other equipment have to be designed with mechanical and electrical principles in mind. They must also take into account the characteristics of the land, the needs of the human operators, and the demands of working with particular agricultural products. Many crops require specialized equipment to be successfully mechanically harvested. Thus a pea harvester may have several components—one that lifts the vines and cuts them from the plant, one that strips pea pods from the stalk, and one that threshes the pods, causing them to open and release the peas inside them. Another example of an agricultural engineering application is the development of automatic milking machines that attach to the udders of a cow and enable dairy farmers to dispense with the arduous task of milking each animal by hand.

Soil management and water management are also important priorities for bioengineers working in agricultural settings. They may design structures to control the flow of water, such as dams or reservoirs. They may develop water-treatment systems to purify wastewater coming out of industrial agricultural production centers. Alternatively, they may use soil walls or cover crops to reduce the amount of pesticides and nutrients that run off from the soil, as well as the amount of erosion that takes place as a result of watering or rainfall.

Environmental and Ecological Applications

Environmental engineers and ecological engineers study the impact of human activity on the environment, as well as the ways in which humans respond to different features of their environments. They use engineering principles to clean, control, and improve the quality of natural spaces. In addition, they find ways to make human interactions with environmental resources more sustainable. For example, the reduction and remediation of pollution is an important area of concern. Therefore, an environmental engineer may study the pathways and rates at which volatile organic compoundsfound in many paints, adhesives, tiles, wall coverings, and furniturereact with other gases in the air, causing smog and other forms of air pollution. They may design and build sound walls in residential areas to cut down on the amount of noise pollution caused by airplanes taking off and landing or cars racing up and down highways.

The life-support systems designed by bioengineers to enable astronauts to survive in the harsh conditions of outer space are also a form of environmental engineering. Temperatures around a space shuttle can vary wildly, depending on which side of the vehicle is facing the Sun at any given moment. A complex system of heating, insulation, and ventilation helps regulate the temperature inside the cabin. Because space is a vacuum, the shuttle itself must be filled with pressurized gas. In addition, levels of oxygen, carbon dioxide, and nitrogen within the cabin must be controlled so that they resemble the atmosphere on Earth. Oxygen is stored on board in tanks, and additional supplies of the essential gas are produced from electrolyzed water. In turn, carbon dioxide is channeled out of the shuttle through vents.

Geoengineering

Geoengineering is an emerging subfield of bioengineering that is still largely theoretical. It involves the large-scale modification of environmental processes in an attempt to counteract the effects of human activity leading to climate change. One proposed geoengineering project involves depositing a fine dust of iron particles into the ocean in an attempt to increase the rate at which algae grows in the water. Since algae absorbs carbon dioxide as it photosynthesizes, essentially trapping and containing it, this would be a means of reducing the amount of this greenhouse gas in the atmosphere. Other geoengineering proposals include the suggestion that it might be possible to spray sulfur dust into the high atmosphere to reflect some of the Sun's light and heat back into space, or to spray drops of seawater high up into the air so that the salt particles they contain would be absorbed into the clouds, making them thicker and more able to reflect sunlight.

Careers and Course Work

Although bioengineering is a field that exists at the intersection between biology and engineering, the most common path for professionals in the field is to first become trained as engineers and later apply their technical knowledge to problems in the life sciences. A less common path is to pursue a medical degree and become a clinical researcher. At the high school level, it is important to cover a broad range of mathematical topics, including geometry, calculus, trigonometry, and algebra. Biology, chemistry, and physics should also be among an aspiring bioengineer's course work. At the college level, a student should pursue a Bachelor of Science in engineering. At many institutions, it is possible to further concentrate in a subfield of engineering: Appropriate subfields include biomedical engineering, electrical engineering, mechanical engineering, and chemical engineering. Students should continue to take electives in biology, geology, and other life sciences wherever possible. In addition, English and humanities courses, especially writing classes, can provide the aspiring bioengineer with strong communication skills—important for working collaboratively with colleagues from many different disciplines.

Many, though not all, choose to pursue graduate-level degrees in biomedical engineering, agricultural engineering, environmental engineering, or another subfield of bioengineering. Others go through MBA (Master of Business Administration) programs and combine this training with their engineering background to become entrepreneurs in the bioengineering industry. Additional academic training beyond the undergraduate level is required for careers in academia and higher-level positions in private research and development laboratories. Entry-level technical jobs in bioengineering may require only a bachelor's degree. Internships, such as at biomedical companies, or evidence of experience conducting original research will be helpful in obtaining one's first job.

A variety of career options exist for bioengineers; many work as researchers in academic settings, private industry, government institutions, or research hospitals. Some are faculty members, others administrators, managers, supervisors, or marketing consultants for these same organizations. Many are engaged in designing, developing, and conducting safety and performance testing for bioengineering instruments and devices.

According to the Occupational Outlook Handbook, there were 19,700 bioengineers and biomedical engineers employed in 2024. The handbook projects that there will be 1,100 more jobs for bioengineers and biomedical engineers each year from 2020 to 2030, a job growth rate of about 5 percent.

Social Context and Future Prospects

Bioengineering is a field with the capacity to exert a powerful impact on many aspects of social life. Perhaps most profound are the transformations it has made in health care and medicine. By treating the body as a complex system—looking at it almost as if it were a machine—bioengineers and physicians working together have enabled countless patients to overcome what once might have seemed to be insurmountable damage. If the body is indeed a machine, its parts might be reengineered or replaced entirely with new ones—as when the damaged cilia of individuals with hearing impairments are replaced with electro-mechanical devices. Some aspects of bioengineering, however, have drawn concern from observers who worry that there may be no limit to the scientific ability to interfere with biological processes. Transgenic foods are one area in which a contentious debate has sprung up. Some are convinced that the ecological and health ramifications of growing and ingesting crops that contain genetic information from more than one species have not yet been fully explored. Stem cell research is another area of controversysome critics are uncomfortable with the fact that human embryonic stem cells are being obtained from aborted fetuses or fertilized eggs that are left over from assisted reproductive technology procedures.

One aspect of bioengineering that has been the subject of both fear and hope in the twenty-first century is the question of whether it might be possible to stop or even reverse the harmful effects of climate change by carefully and deliberately interfering with certain geological processes. Some believe that geoengineering could help the international community avoid the devastating effects of global warming predicted by scientists, such as widespread flooding, droughts, and crop failure. Others, however, warn that any attempt to interfere with complex environmental systems on a global scale could have wildly unpredictable results. Geoengineering is especially controversial because such projects could potentially be carried out unilaterally by countries acting without international agreement and yet have repercussions that could be felt all across the world.

By 2030, bioengineers may be involved in earth-saving endeavors as designing bio-materials that replace plastics. They may also be identifying plants or hybrid vegetation that can efficiently extract carbon from the atmosphere. Above all, bioengineers must conceive of processes and products that fall within ethical guidelines. Important in this regard will be the implementation of safeguards that will prevent these technologies from being misapplied in harmful ways.

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