JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV BIOMEDICAL INSTRUMENTATION Previous Question Paper (March - 2021 - R16)
Answer any five questions. All questions carry equal marks.
Main
List and explain the Static and Dynamic Characteristics of Medical Instruments.
Answer
The performance of medical instruments is evaluated using static and dynamic characteristics. Static characteristics describe the instrument's performance when the measured variable is constant or varies slowly over time, while dynamic characteristics describe the response to rapidly changing inputs.
Static Characteristics:
- Accuracy: The closeness of the measured value to the true value of the physiological parameter.
- Precision: The ability of the instrument to reproduce the same reading consistently for multiple measurements of the same input.
- Sensitivity: The ratio of the change in output signal to the change in the input physiological signal (ΔOutput / ΔInput).
- Linearity: The degree to which the calibration curve of the instrument follows a straight line.
- Resolution: The smallest change in the input parameter that can be detected and displayed by the instrument.
- Hysteresis: The difference in output readings for the same input when approached from increasing versus decreasing directions.
- Drift: The variation in the output over time while the input remains constant, often due to thermal or electronic instability.
Dynamic Characteristics:
These define how the instrument responds to time-varying signals, such as ECG or blood pressure waveforms.
- Frequency Response: The range of frequencies over which the instrument can accurately reproduce the input signal without significant amplitude or phase distortion.
- Rise Time: The time required for the output to rise from 10% to 90% of its final value following a step input.
- Settling Time: The time taken for the output to reach and remain within a specified error band of its final steady-state value.
- Time Constant: A measure of the speed of response for first-order systems, representing the time taken to reach approximately 63.2% of the final value.
- Damping Ratio: A parameter that describes how oscillations in the system decay over time; it is critical for ensuring the instrument does not overshoot or oscillate excessively when measuring rapid physiological changes.
Derive the Nernst equation of resting membrane potential.
Answer
The resting membrane potential arises from the unequal distribution of ions across the cell membrane. For a single permeable ion, the Nernst equation describes the equilibrium potential where the chemical gradient equals the electrical gradient.
At equilibrium, the chemical potential energy equals the electrical potential energy:
The chemical potential for an ion is given by:
Equating the potentials for inside and outside the membrane:
Rearranging for the potential difference (V = V_in - V_out):
Converting to base-10 logarithm at body temperature (37°C), the equation becomes:
Where R is the gas constant, T is absolute temperature, z is the ion valence, F is Faraday's constant, and C is the ion concentration.
What are the different stages of action potential? Explain.
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Explain any two methods of blood flow measurements.
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Describe ECG waveform with respect to electro mechanical activity of the heart.
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Explain EEG waveform for various conditions of brain.
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Describe in detail about ECG machine.
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Describe in detail about Haemodialysis machine.
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Explain the working of Spirometer with experimental setup.
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