Development of a Oxygen Sensor for Marine ... - DTU Nanotech

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24 CHAPTER 3. THEORY OF THE CLARK SENSOR Working Electrode Constant E required Reference Electrode Current Input Counter Electrode Figure 3.6: A basic electrochemical cell with a third electrode (Counter Electrode) added to control the potential. a non-inverting. If a current/voltage is feed into the non-inverting part, an amplified current/volage will be produced, while feeding it into the inverting part will maintain the magnitude, while switching the sign (+ to − or − to +). By closing the loop between in- and output, the voltage difference between the two inputs of the amplifier will fall. An increase in the voltage in the inverting input will force a complementary current on the output, which will counteract the difference in input voltage. Connecting the Reference Electrode to the inverting input, the Working Electrode to the non-inverting, and the Counter Electrode to the output will give this: Between the Working Electrode and the Reference Electrode the difference will now be amplified and inverted by the amplifier, the circuit will be closed by the electrochemical cell, where the current runs through the electrolyte from the Counter Electrode to the Working Electrode. This will polarize the Working Electrode, so that the input difference between that and the Reference Electrode will be zero. In doing so, the Working Electrode and the Reference Electrode potential is kept level. To shift the Working Electrode potential to some other reference value in regards to the Reference Electrode, a voltage in series between the input to the Reference Electrode and the Reference Electrode itself must be inserted. Also to measure the current running through the Counter Electrode, a resistor is used in the wiring of the Counter Electrode, over which a voltage that is proportional to the
3.2. THE POTENTIOSTAT 25 Working Electrode Reference Electrode + OPAMP − Counter Electrode Figure 3.7: Using the OPAMP as a potentiostat. current is measured (See Figure 3.8) Working Electrode Reference Electrode + OPAMP − R Counter Electrode Figure 3.8: Resistor added to measure the current running through the Counter Electrode. Of course a more complex electronic system is still needed to protect the potential amplifier from voltage shocks, to counteract noise and other miscellaneous problems with electrical systems. V
Page 1 and 2: Development of a Oxygen Sensor for
Page 3: Abstract This thesis described the
Page 7 and 8: Contents 1 Introduction 1 1.1 Disso
Page 9 and 10: CONTENTS vii B Fabrication Process
Page 11 and 12: Chapter 1 Introduction Roughly 70 %
Page 13 and 14: 1.1. DISSOLVED OXYGEN LEVEL 3 K = a
Page 15 and 16: 1.2. THESIS OUTLINE 5 In Chapter 8
Page 17 and 18: Chapter 2 Optodes and ISFET There a
Page 19 and 20: 2.2. ISFET (ION SELECTIVE FIELD EFF
Page 21 and 22: 2.3. SUMMARY 11 of oxygen molecules
Page 23 and 24: Chapter 3 Theory of the Clark Senso
Page 25 and 26: 3.1. CHEMISTRY OF THE CLARK SENSOR
Page 33: 3.2. THE POTENTIOSTAT 23 Reference
Page 37 and 38: Chapter 4 System Design The sensor
Page 39 and 40: 4.2. ACTUAL DESIGN 29 seen on figur
Page 41 and 42: 4.2. ACTUAL DESIGN 31 The third des
Page 43 and 44: 4.3. TEMPERATURE SENSOR 33 Figure 4
Page 45 and 46: 4.3. TEMPERATURE SENSOR 35 a Pt300,
Page 47 and 48: 4.4. PACKAGING 37 Figure 4.11: Clos
Page 49 and 50: 4.4. PACKAGING 39 90 mm 15 mm 6 mm
Page 51 and 52: Chapter 5 Fabrication The fabricati
Page 53 and 54: 5.1. PROCESSING 43 Figure 5.4: Alig
Page 55 and 56: 5.2. BACK-END PROCESSING 45 under e
Page 57 and 58: 5.2. BACK-END PROCESSING 47 5.2.2 A
Page 59 and 60: Chapter 6 Problems and Solutions In
Page 61 and 62: 6.1. WIREBONDING 51 make a line bet
Page 63 and 64: 6.2. THE FLEX PRINT 53 The reason b
Page 65 and 66: 6.3. THE ’O’-RING 55 Figure 6.8
Page 67 and 68: Chapter 7 Evaluation of Results and
Page 69 and 70: 7.2. TEMPERATURE SENSOR 59 Figure 7
Page 71 and 72: 7.4. SUMMARY 61 Figure 7.5: Polarog
Page 73 and 74: Chapter 8 Conclusion The primary go
Page 75 and 76: Bibliography [1] http://earthobserv
Page 77 and 78: BIBLIOGRAPHY 67 [26] W.E. Morf. The
Page 79 and 80: Appendix A Silicide Recipe The foll
Page 81 and 82: Appendix B Fabrication Process 71
Page 84 and 85:
74 APPENDIX B. FABRICATION PROCESS
Page 86:
76 APPENDIX C. PROCESS SEQUENCE
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