BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 1 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure BIRMINGHAM CITY UNIVERSITY UNDERGRADUATE EXAMINATION BEng/MEng Biomedical Engineering MIM5107 Medical Instrumentation and Measurement Exam Online Closed Book Exam Date/Time: Available on Moodle Open: Monday 2nd June 2021 at 9am British Summer Time (GMT + 1) Close: Monday 2nd June 2021 at 5pm British Summer Time (GMT + 1) Duration: 8 hours (Actual writing duration: 50 mins + Additional time is given for 10min reading time, scanning and uploading your answer sheets) You should spend no longer, than the scheduled duration of the exam plus any approved additional time that you have been granted in an exam concession (e.g., Student Support Summary) You may complete the exam at any time during the scheduled 8-hour period, ensuring you submit your answers by the above deadline. This takes account of any reasonable adjustments. Module Leader: Dr. George Oguntala Learning Outcomes Assessed: 1. Familiarisation with fundamental physiological principles of bio-potentials 2. Identification and evaluation of characteristics of different bio-electrodes, bio- amplifiers, and different recorders available for various physiological measurement 3. Detailed description of detection and visualisation of physiological signals using bio-potential and bio-impedance modalities Reading time: The purpose of reading time is to enable candidates to check that the question paper is complete. Reading time also allows students to prepare by ensuring they are clear on the requirements of the exam. Candidates are permitted to annotate the question paper during reading time and should be aware their question paper will not be sent for marking. Candidates are not permitted to start completing their answer books until the end of the reading time. BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 2 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure Instructions to Candidates: • Answer all questions. • All questions carry marks distributed across each section. • The use of a calculator is permitted. • Based on the outcomes of consultation with students (across various levels (4, 5, 6, and 7)) and staff within the Biomedical Engineering course, we are treating this online examination as a time-limited Closed Book assessment, and you are therefore not permitted to refer to written and online materials to aid you in your answers. Consequently, any suspected cases of academic misconduct (such as; collusion or plagiarism), will be referred to the Faculty ‘Student Governance’ team and if proven, in line with the academic misconduct policy appropriate penalty will be applied. • If you are taking an exam where you’ll need to write equations, or draw diagrams you may be asked to hand-write your answers and take pictures of your answer pages to upload using your phone’s camera or the one on another device. Candidates should ensure that all workings are shown clearly. • There will be a submission point on the VLE site for your module Moodle page. You should submit your answers to that point in the same way that you would normally submit an essay or coursework. • Please leave enough time to submit your work before the end of your allocated slot. Any delay in submitting your online exam script, maximum of 30 minutes post your allocated time slot, may result in you being marked as a Non-Submission for your exam. If you foresee or anticipate any personal or technical circumstances limiting the submission of your online exam, to your Moodle submission portal, within your allocated time, you need to touch base with your module leader as soon as possible via the communication platform as highlighted below . • Your tutor will be available from 9am - 5pm British Summer Time (GMT + 1) on Microsoft teams on the day of your exam, if you want to raise any urgent queries about the paper or communicate regarding an extenuating circumstance. Given the above instructions, to upkeep the integrity and conduct of a closed book online exam, all candidates should carefully consider and plan to overcome any technical or non-technical / personal issues, limiting you to undertake and submit an online exam, in a conducive assessment environment, ahead of the impending assessment date. • If candidates foresee any such issues, you are required to immediately contact the module/course team, ahead of the assessment date, to explore other alternative arrangements and overcome any untoward circumstances on the day of your assessment. BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 3 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure USEFUL FORMULAS BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 4 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure Assessment Task 1. (a). You are required to design a biopotential sensor to measure a single pyramidal cell that gives a 500mV action potential in 5ms. The cell diameter is 40μm and its membrane capacitance is 1μF/cm2. Assume σ = 0.1Ω-1m-1. Determine the amplitude of the extracellular potential at 20cm distance? (11 marks) (b). From your result in (a), discuss how you will maintain a zero-net current in the cell. (5 marks) (c). You realise the biopotential is weak for recording and are required to design a biopotential amplifier as shown below. Given R1 = 4KΩ, R2 = 5KΩ, R3 = 3KΩ, R4 = 2KΩ. Assume the OpAmp is ideal, and all the resistances have zero error tolerance. Calculate i. Output voltage, Vout ii. Gain of the amplifier iii. Power Gain (in decibel) iv. Voltage Gain (in decibel) (16 marks) BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 5 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure 2. Cardiomyocytes have a typical membrane time constant of 2ms and start to fibrillate at above 100 mA. (a) Assume a person is stricken with 200 kV lightning. The current enters and exits the body through the skin (Rskin = 100 kΩ). How much current will flow through the victim? Assume the internal body resistance is negligible compared with the skin resistance. (5 marks) (b) If 20% of the lightning strike’s current mentioned in part (a) passes through the heart, how long can the victim withstand the strike before suffering cardiac arrest? (10 marks) (c) Lightning strikes are not the only electrical hazard to worry about. Within a clinical environment, ground faults can also make a piece of medical equipment dangerous to use without any outward signs of a problem. You are designing a 12–lead ECG powered by a 240 VAC supply. As a biomedical engineer, you add resistors in series with each ECG electrode lead wire as part of the device’s overall safety design. Using the figure below, specify what resistor value you should use so that any ground fault currents are imperceptible. (10 marks) Graph source: International Electrotechnical Commission (IEC) standard 60479 BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 6 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure Note: AC-1 imperceptible AC-2 perceptible but no muscle reaction AC-3 muscle contraction with reversible effects AC-4 possible irreversible effects AC-4.1 up to 5% probability of heart fibrillation AC-4.2 5-50% probability of fibrillation AC-4.3 over 50% probability of fibrillation 3. As a biomedical engineer, you are called to assist the lab technicians who are on a routine check-up on a patient’s blood sample using some electrodes connected to an arterial gas meter, but unfortunately whose meters are broken. You are required to use your multimeter to measure the electrodes directly and calculate pH, PCO2, and [O2]. (a). You measure a voltage of -60mV across the pH probe. The probe uses a saturated HCl concentration of 100mM. What is the blood sample’s pH? (5 marks) (b). You calibrate the PCO2 electrode with a standard (pH = 7.4, PCO2 = 40 mmHg). Then, you put a sample of the blood from part (a) in the PCO2 electrode with 25 mM NaHCO3. What is the sample’s PCO2? (8 marks) (c). For measuring PO2, you construct a trans-impedance amplifier to convert the current output from the Clark electrode to a voltage as shown below: BIRMINGHAM CITY UNIVERSITY ONLINE EXAMINATION [ENG5107 Medical Instrumentation and Measurement Online Examination] Page 7 of 7 This examination is subject to the Code of Practice – Conduct of Examinations and the Student Disciplinary Procedure Assume R1 = 1MΩ, R2 = 50kΩ, and R3 = 5MΩ and the blood sample flow through the Clark electrode at 50mL/s which has 0.7V applied across it. What is the sample’s [O2] when you measure a voltage of 5.5V at Vout? (10 marks) END OF PAPER
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