List of top Sensors and Bioinstrumentation Questions

A Hall effect flow meter is used to measure the volumetric flow through a blood vessel. The system calculated the flow rate to be 100 cm\(^3\cdot\text{s}^{-1}\). Later, calibration revealed that (i) the voltmeter was reading 40% higher than actual, and (ii) the caliper was measuring the vessel diameter 10% smaller than actual. Assuming a uniform flow profile and ignoring viscosity, the actual blood flow is _________ cm\(^3\cdot\text{s}^{-1}\) (rounded off to two decimal places).

A catheter based arterial blood pressure measurement device uses a flexible diaphragm mounted with four identical strain gauges in a Wheatstone bridge configuration as shown in the figure. Assume that the strain gauges have a nominal resistance value of \(R_G = 10\ \text{k}\Omega\), Gauge Factor \(G = 40\) and Young’s Modulus \(E = 10\ \text{MPa}\). Blood pressure variations result in small finite change in strain \(\varepsilon (\varepsilon>0)\). If \(V_o\) is the output voltage of the Wheatstone bridge and \(\sigma\) is the stress in MPa, the sensitivity \[ \frac{V_o}{\sigma} \] is ________ V.MPa\(^{-1}\).

Which of the following statements related to biomedical measurements are TRUE?

The thickness of piezoelectric crystal (PZT5A) used in ultrasound applications will determine the resonant frequency of the transducer. To work at a resonance frequency of 5 MHz, the thickness of a PZT5A transducer must be ________ mm (rounded off to three decimal places).

Which of the following statements related to the safety of biomedical instruments are TRUE?

Which of the following statements related to the operating principle of pulse oximetry are CORRECT?

A pacemaker was implanted in a cardiac patient. It has a battery of 2.4 A·h (Ampere·hour). It is designed to deliver a rectangular pulse of amplitude 1.5 V for 1 ms ON time for every one second. The electrode-heart resistance is 150 Ω. Assuming the current drained from the battery is negligible, the lifetime of the pacemaker is \(\underline{\hspace{1cm}}\) years (rounded off to the nearest integer).

An inexperienced clinician was measuring the cardiac output of a healthy human by thermodilution technique. A 2.0 mL of cold saline solution of volume \( V_i \) at \( 7^\circ C \) was injected at the entrance of the right atrium. The change in blood temperature \( \int_0^{t_1} \Delta T_b \, dt \) at the pulmonary artery was measured to be \(-20\) Kelvin-second. The cardiac output \( F \) was calculated using the following formula \[ F = \frac{Q}{\rho_b c_b \int_0^{t_1} \Delta T_b \, dt}, \] where \( Q \) is the heat content of injectate in Joules, given by \( V_i \Delta T_i \rho_i c_i \) and \( \Delta T_i \) is the temperature difference between the injectate and blood. It was assumed that the density of blood (\( \rho_b \) in kg/m\(^3\)) and the specific heat capacity of blood (\( c_b \) in J/(kg.K)) were respectively equal to that of the injectate \( \rho_i \) and \( c_i \).
The clinician realized that there was an error in the measurement of \( F \). Which of the following is TRUE?

In comparison to ECG amplifiers, the surface-EMG amplifiers have

Which of the following displacement sensors is known to have high sensitivity and a relatively larger measurement range?

Which of the following temperature sensors is used in contact-type digital thermometers for measuring body temperature?