File

1. Describe the tasks in Biomedical Electronics.  









  

Repairs, calibrates, and maintains medical equipment instrumentation used in health-care delivery field Inspects and installs medical & related technical equipment in medical research facilities for use by physicians, nurses, scientists, or engineers involved in researching, monitoring, diagnosing and treating physical ailments or dysfunctions Services various equipment & apparatus, like patient monitors, electrocardiographs, blood-gas analyzers, x-ray units, defibrillators, electrosurgical units, anesthesia apparatus, pacemakers, blood-pressure transducers, spirometers, sterilizers, diathermy equipment, in-house television systems, patient-care computers, other related technical paraphernalia Repairs, calibrates, and maintains equipment, using handtools, power tools, measuring devices, and knowledge of manufacturers manuals, troubleshooting techniques, and preventive-maintenance schedules Safety-tests medical equipment and health-care facilitys structural environment to make sure patient staff safety from electrical or mechanical hazards Consults with medical or research staff to ascertain that equipment functions properly and safely, utilizing knowledge of electronics, medical terminology, human anatomy physiology, chemistry, and physics May demonstrate explain correct operation of equipment to medical personnel May modify or develop instruments or devices, under supervision of medical or engineering staff May work as salesperson or service technician for equipment manufacturers or their sales representatives.

2. Compare and contrast invasive and non-invasive measurements used in bioelectronic instruments.

forms

of

Invasive procedures involve the placement of transducers or other devices inside the body, such as needle electrodes to record MUAPs, or insertion of cathetertip sensors into the heart via a major artery or vein to record intracardiac signals. In a direct measurement, the measuring physiological directly such as the average volume of blood flow in an artery. Direct electrical recording of the bio-signal in nerve fibers using an implantable electrode system is an example of an invasive measurement. Noninvasive are desirable in order to minimize risk to the subject. Recording of the ECG using limp or chest electrodes, the EMG with surface electrodes, or the PCG with microphones or accelerometer placed on the chest are noninvasive procedures. In an indirect measurement, it measures a parameter related to the physiological parameter of interest indirectly such as ECG recording at the body surface. It is related to propagation of the electric signals in the heart, but is not a direct measurement of the propagation waveform. An imaging system measuring blood flow dynamics in an artery (e.g., ultrasound blood flow imaging) is an example of a noninvasive measurement.

Note that make measurements or imaging with X-rays or ultrasound may not be classified as invasive procedures, as they involve penetration of the body with externally administered radiation, even though the radiation is invisible and there is no visible puncturing or invasion of the body.

3. Describe the frequency response, linearity, and noise of a transducer. Frequency response. The time taken by a sensor to approach its true output when subjected to a step input is sometimes referred to as its response time. It is more usual, however, to quote a sensor as having a flat response between specified limits of frequency. This is known as the frequency response, and it indicates that if the sensor is subjected to sinusoidally oscillating input of constant amplitude, the output will faithfully reproduce a signal proportional to the input. Linearity. For successive equal increments of the input, the linearity is the deviation of the plotted transducer output from a straight line. This is often defined in terms of a percentage of the maximum or full scale output. Noise. Noise (in the transducer) consists of signals generated within the transducer, independent of the input signal, which contribute to the output. Such signals may be intrinsic to the transducer (for example, due to thermal fluctuations of carrier concentrations in a semiconductor), or be generated by interaction with the environment (for example, by RF pickup). 4. Describe the use of amplifiers used in bioelectronic measurements. The purpose of amplifiers in general, is to boost the level of the low-voltages and currents produced by the body. Heart-beat voltages and currents are in the milli-volt and micro-amp regimes. Brain waves are also very tiny. In order for instruments to record and display such signals they need to be amplified. Now, it is important in medical applications that the body be protected from accidental electric shock by these instruments. This is why these types of amplifiers are used. It is important to keep the bias currents from these amplifiers very very low (nano-amps, even pico-amps), so they will not shock the body. The types of amplifiers provide these low bias and offset currents. Bias and offset currents are currents that come out of the input side of the amplifier, right into the leads that are attached to the body for measuring heartbeats, brainwaves, etc. Op amps configured as a differential or instrumentation amplifier provide very high gain, yet at the same time very low bias and offset current. Electrometers are amplifiers with FET or MOSFET inputs that have the lowest bias currents available. Sometimes they have bias currents so low, you can actually measure them in terms of 1000s of electrons per second (versus 1 amp which is over a billion-billion electrons per second). Carrier amplifiers only look at AC signals. There

is no DC current that flows from the input signal source (somewhere on the body) to the amplifier, so absolutely no bias current flows). The signal modulates an RF carrier that is passed through capacitors to block any DC bias current. Once amplified and detected (rectified), the original signal is reproduced. 5. Describe the use of analog and digital readout devices used in bioelectronic measurements. Display equipment are used to present the signal from the signal conditioning equipment in a form which can be understood by the user. The output display equipment may be a printer, a display monitor, or a storage equipment.

LITERATURE SOURCES: https://books.google.com.ph/books? id=I5598H1Nx70C&pg=PA16&lpg=PA16&dq=invasive+versus+noninvasive+of+bio electronic+instruments&source=bl&ots=c4a1wGuo1&sig=b7_0YcYSGJgFVJ4PYLKqjAJz8BQ&hl=en&sa=X&ei=HzqHVecLYLGuATqz4C4Bw&redir_esc=y#v=onepage&q=invasive%20versus %20noninvasive%20of%20bioelectronic%20instruments&f=false http://www.mfg.mtu.edu/cyberman/machtool/machtool/sensors/fundamental.html https://answers.yahoo.com/question/index?qid=20071125014430AAC92vZ https://books.google.com.ph/books? id=I5598H1Nx70C&pg=PA16&lpg=PA16&dq=invasive+versus+noninvasive+of+bio electronic+instrumentation&source=bl&ots=c4a1wGwlU&sig=qhUcfPc4quXJh1EKwYdOAQ66CBQ&hl=en&sa=X&ei=wDqHVc3IKYGfu gS8rqeADg&redir_esc=y#v=onepage&q=invasive%20versus%20noninvasive%20of %20bioelectronic%20instrumentation&f=false