BE/B Eng Bachelor of Engineering Bachelor of Biomedical Engineering 4 — Questions and Answers
Question 1: In biomaterials science, what is the 'foreign body response' (FBR)?
- The specific immune response mediated by B-lymphocytes against implanted polymer antigens
- A cascade of inflammatory and wound-healing events triggered by implantation of a non-biological material (Correct answer)
- The selective absorption of albumin onto a device surface that prevents platelet adhesion
- The electrochemical corrosion of metallic implants in physiological saline environments
Correct answer: A cascade of inflammatory and wound-healing events triggered by implantation of a non-biological material
The foreign body response is a chronic inflammatory reaction in which macrophages and foreign body giant cells surround an implant, often leading to fibrous encapsulation that can impair device function.
Question 2: A prosthetic heart valve must be designed to withstand cyclic loading. Which material failure mode is most relevant to this long-term cyclic stress?
- Creep failure under constant static load
- Fatigue failure from repeated stress cycles (Correct answer)
- Brittle fracture from a single high-impact event
- Ductile overload failure from exceeding the yield strength
Correct answer: Fatigue failure from repeated stress cycles
A prosthetic heart valve opens and closes approximately 40 million times per year; fatigue failure, which occurs at stress levels below the yield strength after many cycles, is the dominant design concern.
Question 3: Which physiological parameter does pulse oximetry non-invasively estimate?
- Partial pressure of arterial carbon dioxide (PaCO₂)
- Arterial oxygen saturation (SpO₂) (Correct answer)
- Cardiac output (CO)
- Blood pH
Correct answer: Arterial oxygen saturation (SpO₂)
Pulse oximetry uses two wavelengths of light (red and infrared) to measure the differential absorption by oxyhemoglobin and deoxyhemoglobin, providing a non-invasive estimate of arterial oxygen saturation.
Question 4: In a drug delivery system, what does 'zero-order release kinetics' mean?
- Drug release rate that decreases exponentially as the drug concentration in the carrier drops
- Drug release at a constant rate independent of the remaining drug concentration in the device (Correct answer)
- Drug release that is triggered only by a specific pH in the surrounding tissue
- Instantaneous release of the entire drug payload upon implantation
Correct answer: Drug release at a constant rate independent of the remaining drug concentration in the device
Zero-order kinetics describes a constant drug release rate over time, which is ideal for maintaining a steady therapeutic plasma concentration and avoiding peaks and troughs.
Question 5: In a biomedical signal, 'aliasing' occurs when the sampling frequency is:
- Greater than twice the highest frequency component of the signal (above Nyquist rate)
- Less than twice the highest frequency component of the signal (below Nyquist rate) (Correct answer)
- Equal to the frequency of the dominant signal component
- Greater than the signal amplitude in volts
Correct answer: Less than twice the highest frequency component of the signal (below Nyquist rate)
According to the Nyquist-Shannon sampling theorem, if the sampling frequency is less than twice the signal's highest frequency, high-frequency components are misrepresented as lower-frequency artifacts called aliases.
Question 6: What is the primary advantage of using hydroxyapatite (HA) as a coating on orthopedic implants?
- It provides a lubricious surface that reduces friction at articulating interfaces
- Its chemical similarity to bone mineral promotes osseointegration and bone bonding (Correct answer)
- It acts as an antibiotic carrier to prevent peri-implant infection
- It increases the electrical conductivity of the implant to stimulate bone growth electrically
Correct answer: Its chemical similarity to bone mineral promotes osseointegration and bone bonding
Hydroxyapatite is chemically and structurally similar to the mineral phase of bone, and its use as a coating promotes direct bone apposition and biological fixation (osseointegration) without fibrous tissue interposition.
Question 7: In a neural prosthetic system, what is 'spike sorting'?
- Filtering the raw neural signal to remove low-frequency local field potentials
- The process of classifying recorded voltage waveforms to identify action potentials from individual neurons (Correct answer)
- Compressing neural data for wireless transmission using entropy coding
- Calibrating electrode impedance to minimize charge injection artifacts
Correct answer: The process of classifying recorded voltage waveforms to identify action potentials from individual neurons
Spike sorting is a signal-processing step that identifies and classifies action potential waveforms recorded on an electrode to attribute them to individual neurons based on waveform shape and amplitude.
BE/B Eng Bachelor of Engineering Bachelor of Biomedical Engineering 4
In biomaterials science, what is the 'foreign body response' (FBR)?