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56 Cards in this Set
- Front
- Back
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What is Bioinstrumentation?
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Application of electronics, biological process measurment principles and techniques to develop diagnosis and treatment biomedical devices.
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What 5 components are needed in every bioinstrument?
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1. Measurand
2. Sensor 3. Signal Conditioning 4. Output Display 5. Auxilary elements |
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What is a Measurand?
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The physical quantity, property, or condition that the system measures.
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The measurand can be grouped into what 8 categories?
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1. Biopotential
2. Pressure 3. Flow 4. Dimensions 5. Displacement 6. Impedance 7. Temperature 9. Chemical concentrations |
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The accessibility of the measurand is important because it may be what 4 things?
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1. Internal
2. On the body surface 3. Emanate from the body 4. Derived from tissue sample |
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What is a Sensor?
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Device that converts a physical measurand into a electrical output.
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A sensor should only respond to what?
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The form of energy present in the measurand.
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What is Signal Conditioning?
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Processing that amplifies and filters sensor signals.
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Signal conditioning can do 5 things, if needed?
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1. Filtering out noise
2. Sorting 3. Amplifying 4. Data Storage 5. Output conversion - analog to digital, time to freq. domain |
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Output Display can be what 5 things?
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1. Numerical or graphical
2. Discrete or continuous 3. Permanent or temporary 4. Visual or auditory 5. On-site or remote |
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What are the 5 Operational Modes?
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1. Direct-Indirect Modes
2. Sampling and Continuous Modes 3. Generating and Modulating Modes 4. Analog and Digital Modes 5. Real-time and Delayed-time Modes |
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What is the Direct Mode?
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The desired measurand can be interfaced directly to a sensor because it is readily accessible.
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What is the Indirect Mode? Example?
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The desired measurand is not readily accessible like cardiac output (which has to be determined by measuring respiration and [blood gas])
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What is Sampling and Continuous Mode?
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Sampling Mode is where the measurand is something that changes slowly and thus can be sampled infrequently while Continues Mode is where the measurand needs to be monitored continuously.
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What is a Generating Sensor?
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A sensor that produces its own signal output from energy taken DIRECTLY from the measurand
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What is a Modulating Sensor?
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Sensor that uses the measurand to ALTER the flow of energy form an external source in a way that affects the output of the sensor.
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What is the Analog Mode?
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Continuous signal that is able to take on any value within the dynamic range.
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What is the Digital Mode?
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Discrete signals that are able to take on only a finite number of different values.
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What are some advantages of the Digital Mode?
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Greater accuracy, repeatability, reliability, immunity to noise, and easily integrated into computers.
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What are the Real-Time and Delayed-Time Modes?
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Sensors must acquire signals in real time as the signals occur (real time) but the output of the measurement system may not have to display the result immediately (delayed time)
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The study of biomedical instruments can be approached from what 4 viewpoints? Add examples.
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1. Quantity sensed - pressure, flow, [ion], temp.
2. Principle of Transduction - resistive, inductive, electrochemical, ultrasonic, piezoelectric 3. Organ System - cardiovascular, nervous, endocrine 4. Clinical Medicine Specialties - pediatrics, cardiology, etc. |
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What are the 3 types of Inputs?
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1. Desired
2. Interfering 3. Modifying |
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What is Desired Input?
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The measurand that the instrument is designed to isolate
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What is Interfering Input?
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Qualities that inadvertently affect the instrument
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What is Modifying Inputs?
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Undesired quantities that indirectly affect the output by altering the performance of the instrument itself.
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What is Inherent Insensitivity?
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An ideal situation where all the instrument components are inherently sensitive to ONLY the desired inputs. Interfering and modifying have NO EFFECT.
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What if a modifying input can not be avoided?
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Improved instrument performance requires a strategy that makes the output less dependent on the transfer function.
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What is Negative Feedback?
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A method of reducing or removing modifying input that would otherwise be unavoidable.
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What is Signal Filtering?
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Separates the signals according to their frequencies
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TRUE OR FALSE: Signal Filtering can be inserted at any place in the system: at instrument input, at some point within the instrument, or instrument output.
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TRUE!!
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Input filter blocks what input but not what?
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Blocks interfering and modifying input but not the desired input.
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Output filtering is possible, but it is more difficult because of why?
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Because the desired and undesired output signals are superimposed.
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What are Observational Studies?
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Characteristics of one or more groups of patients are observed and recorded
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What are Experimental Intervention Studies?
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Studies about the effect of a medical procedure or treatment is investigated.
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What is the Coefficient of variation (CV)?
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It standardizes the variation making it possible to compare two numerical distributions measured on different scales.
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What does the Confidence Interval indicate?
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It indicates the degree of confidence we can have that they contain the true mean.
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What does Hypothesis Testing reveal?
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Reveals whether the sample gives enough evidence for us to reject the null hypothesis, which is usually cast as a statement that expresses the opposite of what we think is true.
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What is the the P-Value?
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The probability of obtaining a result at least as extreme as the one that was actually observed, given that the null hypothesis is true.
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What does the P-Value indicate?
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Indicates how often the observed difference would occur by chance alone if, indeed, nothing but chance ere affecting the outcome.
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What is Accuracy?
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The difference between the true value and the measured value divided by the true value.
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What is Precision?
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A measure of the detail in which a quality is expressed.
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What is Resolution?
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The smallest incremental quantity that can be measured with certainty
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What is Reproducibility?
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The ability of an instrument to give the same output for equal inputs applied over some period of time.
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Does Reproducibility imply accuracy?
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NO.
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What is Static Sensitivity?
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The ratio of the incremental output quantity to the incremental input quantity.
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If the measurand quantity starts from 0, what term is synonymous with resolution?
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Threshold
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How is a static calibration performed?
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By holding all inputs (desired, interfering, and modifying) constant except one.
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What is Standard Deviation?
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A measure of the spread of data about the mean
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What does Independent Nonlinearity express?
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Expresses the maximal deviation of points from the least-squares fitted line as either +-A% of the reading or +-B% of full scale, whichever is greater.
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What are required to relate dynamic inputs to dynamic outputs for continuous systems?
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Differential or integral equations!
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What does a Transfer Function for a linear instrumentation or system express?
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Expresses the relationship between the input signal and the output signal
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What order instrument has an ideal dynamic performance? Why?
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Zero order because the output is proportional to the input for all frequencies and there is no amplitude or phase distortion.
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For first-order instruments, what kind of functions offer solutions to this equation when appropriate constants are chosen?
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Exponential!
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If the instrument contains a single energy-storage element, then what order derivative of y(t) is needed?
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First order!
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What are the 7 steps of Commercial Development Process?
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1. Problem initiation
2. Feasibility analysis and product description 3. Written product specification 4. Design and development 5. Clinical feasibility trials 6. Design review, Engineering change order 7. FDA approval, pre-marketing. |
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Choice and Design of instruments depend on what 4 factors? Give examples of each
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1. Signal factors - Sensitivity, range, accuracy
2. Environmental - specificity, stability, power requirements 3. Medical - invasive, non-invasive, material toxicity 4. Economic - cost, availability |
