By George Williamson CBET
For those readers who have the aptitude and would enjoy working with a variety of sophisticated equipment with the satisfaction that they are helping people, "Medical Electronics" may be a career worth looking into for a future livelihood.
Much of the equipment used in medicine today is state-of-the-art or close to it. In this mix of technology you can find RF, Analog, Digital and Microprocessor circuitry, sometimes all in one device. If you are interested in a career that offers great variety, "Medical Electronics" may be for you.
Rarely do you work on the same type of equipment repeatedly. The exception to this may be in "field service." As a "field service" technician or representative, you may be restricted to the repair of one type of equipment. This is the position held by the author when he first entered the area of "Medical Electronics" for a future career. It involved considerable travel, much of it local but it also provided an excellent opportunity to gain much valuable experience. It will require transportation, usually your own vehicle. Some companies provide one, others pay you to use your own. It is not uncommon to drive as much as 10,000 to 15,000 miles per year, in some cases much more.
Planning Your Time
Field service requires careful planning of your time and you must carry an adequate supply of critical parts, especially those that are prone to breakdown or failure. The office or home that you will be working from is invariably too far away to waste time on constant trips for replacement parts. Ideally, you should not have to pick up additional stock of repair parts more than once a week. In some cases, as a "field service technician," you will have to fly to destinations for on-site repairs. This means having tools, test equipment and supplies portable enough to be transported on a plane, therefore, it is not uncommon to see a "Tech" wheeling a stack of suitcases with a collapsible baggage cart. Usually the repairs done in the field are at the "board" level. The defective circuit is located and replaced. The defective board is then returned to a service center for repairs. In some cases, the boards are disposed of when they are not repairable.
Field Service Technicians usually have at least a minimum of test equipment. A small but reliable Digital Multimeter would be essential. You will soon learn various tricks of testing to get the maximum use from your DMM. Other equipment may be added to your tool kit as necessary, such as a reliable oscilloscope. You will soon learn that you must be resourceful. It is a do-it-yourself job. The boss and/or extra manuals and parts are usually too far away to help. Field service is for "self-starters." If you enjoy traveling, this may be the place to start your career in "Medical Electronics." Hospital Service
Hospital service is a totally different area of medical electronics, devoted to people who work in hospitals in various capacities. Unlike field service, the technician is usually only minutes away from his work. Usually called "Biomedical technicians," the people who maintain the medical electronic equipment in hospitals usually receive above average pay for their technical skills. "Biomedical Engineering" is a real challenge. Most biomedical technicians work on a very broad range of equipment. Their workshops will have much more test equipment than carried by the field service technicians. They sometimes have to troubleshoot to the component level. The well-equipped workshop will have service manuals for all of the equipment used in the hospital and, of course, a supply of parts to cope with unexpected emergencies. You will have access to most of this sophisticated test equipment, such as Digital Multimeters, Oscilloscopes, Signal and Function generators and Safety Testers. The "Safety Tester" is of primary importance. This instrument is used to test every electronic device allowed into the hospital. It checks each device for electrical leakage.
Leakage above 100 microamperes could be hazardous, especially to patients with heart problems. All electrical and electronic devices must, therefore, be checked thoroughly as a protection for the patients.
Another electronic device that is used frequently in todays' modern hospital is the "Simulator," which will produce waveforms that mimic various signals that are picked up by a monitor from the patient. Most common is the signal produced by the heart. This is the EKG signal, sometimes called the ECG, an abbreviation for Electrocardiogram. This signal is normally picked up by pad electrodes that are placed on the patient in a proper configuration. There are several ways to place leads on a patient and each has its special purpose. Each combination of 3 leads is one configuration. For example, a 12-lead configuration will have Lead #1, Lead #2, Lead #3, AVR, AVL, AVF, V1, V2, V3, V4, V5, and V6. An electronic machine switches through all 12 lead configurations as the test progresses. A 12-lead EKG gives the most comprehensive picture available of the patients' heart function.
-- This is the normal signal produced by the heart on an EKG. Typical
signal level of "R" wave; 1.0 millivolt. Rate is time from R-wave
to R-wave.
Simulators are connected to the monitor with cables and take the place of the patients' signals.
Besides the EKG signals, simulators can produce blood pressure signals, respiration signals and temperature signals. Most of the technician's testing will involve either the "Safety Analyzer' or "Simulators."
Defibrillator Test Load
This relatively simple device shows how much energy is released by a "Defibrillator" under test.
Other test instruments include ESU testers, Laser
Power Meters, Ultrasound Power Meters, Tachometers for testing centrifuges and Thermometers for testing incubators and baby warmers.
---- BLOOD PRESSURE WAVEFORM BASELINE~ 3 WAVES SHOWN
Monitors
The Biomedical Technician will work on a variety of monitors, mostly for monitoring a patient's heart.
They also monitor a patient's temperature and blood pressure, respiration, blood oxygenation and other parameters. A considerable portion of the technicians' time is spent maintaining monitors. These monitors can be simple little boxes with lights to indicate functions or very large and complex systems that monitor multiple functions. Many monitors will have a CRT screen that will display the information recorded, including waveforms. The more sophisticated heart monitors will detect and flag arrhythmias, which are defects in the heartbeat. This enables doctors to detect problems with their patients easier and quicker.
Transducers
All monitors connect to the patient with a transducer, which connects a non-electrical device or a person to an electrical device. An example of a transducer would be the strain gauge blood pressure transducer. This device has a metal membrane that is thin and sensitive to the pressure of blood pushing a water column against it. The shift in the mechanical position of the membrane is converted to electrical signals in the strain gauge and relayed to the monitor.
Defibrillators
When a patient has a heart stoppage (cardiac arrest), the Defibrillator is used to shock it back into action, typically delivering a burst of energy at 3120 volts. Needless to say, it is extremely important that this device is functioning properly.
Infusion Devices
These devices deliver controlled amounts of fluids intravenously to a patient. A needle is inserted into a vein, typically on the hand and tubing is connected to it. Control of the fluid going into the patient is critical, since these devices are used for intravenous feeding, fluid replacement and administering drugs. As a Biomedical technician, you will test these devices for proper operation. You will also be called upon to repair them when they are defective.
Incubators and Warmers
These are obviously used to keep babies, usually new-born, at a correct temperature for proper growth and health. Your job will require you to verify the correct operation of these devices periodically.
Laboratory Equipment
Most hospitals today have a wide range of laboratory equipment to be periodically checked and maintained and you will usually be called upon to service at least some of it. They can vary from "Tube Rockers" to "Centrifuges" to sophisticated analyzers.
They can all be yours to work on.
Electrosurgical Units (ESUs)
These devices are used instead of scalpels and knives to make incisions in surgery. Radio frequency energy is used and the ESU can be set to coagulate small blood vessels as the surgeon makes the incision. You will be required to periodically test the output for accuracy. You may also be called upon to repair the ESU if it fails to function properly.
Nurse Call Systems
These are really "Paging" or "Intercoms" systems and are frequently the responsibility of the Biomedical technician for proper operation and maintenance. The newer systems are computerized and quite sophisticated.
Computers
Many Biomedical departments are maintaining computers on site. Computers are everywhere and are used extensively in hospitals today, ranging in size from laptop units to huge mainframes. An expertise in computer technology is certainly a plus.
Some other devices that you might work with include:
Anesthesia machines, Analyzers, Blood Gas Machines, Electrocardiographs, Electroencephalographs, Echocardiographs, CAT-scan equipment, Magnetic Resonance Imaging equipment, X-Ray machines, Gamma Cameras, Linear Accelerators, Lasers. Ophthalmoscopes, Fundus Cameras, Slit Lamps and Microscopes.
Training will be a part of your life. As new equipment is introduced, the manufacturers will provide in-service training on site for qualified technicians with additional training and technical support at their offices.
Most employers are looking for technicians with at least a 2-year Associates degree in Electronics or in Biomedical Engineering. For the better (more advanced) positions or to progress to Clinical Engineering, a 4-year degree is required. Clinical Engineering is above Biomedical Engineering and involves more of the medical application. Clinical Engineers work very closely with the doctors and nurses who use this sophisticated equipment, assisting them to get the maximum use from the equipment. They are also frequently involved in supervising Biomedical departments or in Research and Development.
Salary ranges from entry level positions can be as low as $5.00 per hour or as high as $10.00 per hour, depending, to a great extent on the applicants experience and qualifications. Trained technicians can attain annual incomes of $40,000 or more.
Clinical Engineers can exceed $60,000 per year.
Medical Electronics is an interesting and rewarding career. Maybe it is a career for you.
About the author: George Williamson is a Certified Biomedical Engineering Technician. He first became interested in electronics in 1959 and has worked in the Biomedical Engineering department of a major medical center for the past 12 years.
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adapted from: Electronics Handbook 1992