Chapter 1

1. Chapter 1 Measurement Systems

2. Bioinstrumentation • Biomaterials • Biomechanics • Biosignals • Biosystems • Biotransport • Cellular engineering • Clinical engineering • Tissue engineering • Rehabilitation engineering Table 1.1 Biomedical engineers work in a variety of fields.

3. Agriculture - Soil monitoring • Botany - Measurements of metabolism • Genetics - Human genome project • Medicine - Anesthesiology • Microbiology - Tissue analysis • Pharmacology - Chemical reaction monitoring • Veterinary science - Neutering of animals • Zoology - Organ modeling Table 1.2 Biomedical engineers work in a variety of disciplines.

4. Table 1.3 Biomedical engineers may work in a variety of environments.

5. Figure 1.1 In the scientific method, a hypothesis is tested by experiment to determine its validity.

6. Figure 1.2 The physician obtains the history, examines the patient, performs tests to determine the diagnosis and prescribes treatment.

7. Figure 1.3 A typical measurement system uses sensors to measure the variable, has signal processing and display, and may provide feedback.

8. (a) (b) Figure 1.4 (a) Without the clinician, the patient may be operating in an ineffective closed loop system. (b) The clinician provides knowledge to provide an effective closed loop system.

9. Figure 1.5 In some situations, a patient may monitor vital signs and notify a clinician if abnormalities occur.

10. Table 1.4 Common medical measurands.

11. Table 1.5 Sensor specifications for a blood pressure sensor are determined by a committee composed of individuals from academia, industry, hospitals, and government.

12. Figure 1.6 A hysteresis loop. The output curve obtained when increasing the measurand is different from the output obtained when decreasing the measurand.

13. (a) (b) Figure 1.7 (a) A low-sensitivity sensor has low gain. (b) A high sensitivity sensor has high gain.

14. (a) (b) Figure 1.8 (a) Analog signals can have any amplitude value. (b) Digital signals have a limited number of amplitude values.

15. Table 1.6 Specification values for an electrocardiograph are agreed upon by a committee.

16. (b) (a) Figure 1.9 (a) An input signal which exceeds the dynamic range. (b) The resulting amplified signal is saturated at 1 V.

17. (b) (a) Figure 1.10 (a) An input signal without dc offset. (b) An input signal with dc offset.

18. Figure 1.11 Frequency response of the electrocardiograph.

19. (a) (b) Figure 1.12 (a) A linear system fits the equation y = mx + b. Note that all variables are italic. (b) A nonlinear system does not fit a straight line.

20. (a) (b) Figure 1.13 (a) Continuous signals have values at every instant of time. (b) Discrete-time signals are sampled periodically and do not provide values between these sampling times.

21. Table 1.7 Complete blood count for a male subject.

22. (a) (b) Figure 1.14 (a) Signals without noise are uncorrupted. (b) Interference superimposed on signals causes error. Frequency filters can be used to reduce noise and interference.

23. (b) (c) (a) Figure 1.15 (a) Original waveform. (b) An interfering input may shift the baseline. (c) A modifying input may change the gain.

24. (a) (b) Figure 1.16 Data points with (a) low precision and (b) high precision.

25. (a) (b) Figure 1.17 Data points with (a) low accuracy and (b) high accuracy.

26. (a) (b) Figure 1.18 (a) The one-point calibration may miss nonlinearity. (b) The two-point calibration may also miss nonlinearity.

27. Figure 1.19 For the normal distribution, 68% of the data lies within ±1 standard deviation. By measuring samples and averaging, we obtain the estimated mean , which has a smaller standard deviation sx.  is the tail probability that xs does not differ from  by more than .

28. Figure 1.20 A typical Poisson distribution for m = 3.

29. Table 1.8 The four outcomes of hypothesis testing.

30. Table 1.9 Equivalent table of Table 1.8 for results relating to a condition or disease.

31. Figure 1.21 The test result threshold is set to minimize false positives and false negatives.

32. Chapter 2 Basic Concepts of Electronics

33. (a) (b) Figure 2.1 Electric current within a conductor. (a) Random movement of electrons generates no current. (b) A net flow of electrons generated by an external force.

34. Figure 2.2 A model of a straight wire of length l and cross-sectional area A. A potential difference of Vb – Va is maintained across the conductor, setting up an electric field E. This electric field produces a current that is proportional to the potential difference.

35. Figure 2.3 The colored bands that are found on a resistor can be used to determine its resistance. The first and second bands of the resistor give the first two digits of the resistance, and the third band is the multiplier which represents the power of ten of the resistance value. The final band indicates what tolerance value (in %) the resistor possesses. The resistance value written in equation form is AB10C  D%.

36. Table 2.1 The color code for resistors. Each color can indicate a first or second digit, a multiplier, or, in a few cases, a tolerance value.

37. (b) (a) Figure 2.4 (a) The voltage drop created by an element has the polarity of + to – in the direction of current flow. (b) Kirchhoff’s voltage law.

38. I = 9 A Figure 2.5 (a) Kirchhoff’s current law states that the sum of the currents entering a node is 0. (b) Two currents entering and one “negative entering”, or leaving.

39. Figure 2.6 Kirchhoff’s current law example.

40. Figure 2.7 Example of nodal analysis.

41. Figure 2.8 The 1 mV signal from the electrocardiogram is attenuated by the resistive divider formed by the 100 k skin resistance and the 1 M input resistance of the oscilloscope.

42. Figure 2.9 A potentiometer is a three-terminal resistor with an adjustable sliding contact shown by the arrow. The input signal vi is attenuated by the potentiometer to yield an adjustable smaller voltage vo.

43. Figure 2.10 (a) When a shunt resistor, Rp, is placed in parallel with a galvanometer, the device can be used as an ammeter. (b) When a resistor, Rs, is connected in series with the galvanometer, it can be used as a voltmeter.

44. Figure 2.11 A circuit diagram for a Wheatstone bridge. The circuit is often used to measure an unknown resistance Rx, when the three other resistances are known. When the bridge is balanced, no current passes from node a to node b.

45. Figure 2.12 (a) Relationship between voltage and current for a capacitor. (b) Symbol of the capacitor.

46. Figure 2.13 Diagram of a parallel plate capacitor. The component consists of two parallel plates of area A separated by a distance d. When charged, the plates carry equal charges of opposite sign.

47. Figure 2.14 (a) A series combination of two capacitors. (b) A parallel combination of two capacitors.

48. Figure 2.15 (a) Relationship between voltage and current for an inductor. (b) Symbol of the inductor.

49. (b) (a) Figure 2.16 (a) Simple RC circuit with v (0) on capacitor at time t = 0. (b) Normalized voltage across the capacitor for t  0 (normalized means the largest value is 1).

50. (b) (a) Figure 2.17 (a) Series RC circuit with voltage step input at time 0. (b) Normalized voltage across the capacitor.