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

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36 CHAPTER 4. SYSTEM DESIGN the resistance that I want to assign). This in itself may seem straightforward, however neither Rc nor Rsp can be calculated precise, so as a result it isn’t possible to measure Rs accurately. The 4-contact approach solves this problem however; 2 carry the current while the other 2 are used to measure the voltage. While Rc and Rsp is still there, they are now negligible due to the very small current that flows through them, as the voltage is now measured with a potentiometer that draws no current, or with a high impedance voltmeter that draws little current. Temperature Calculated Width Effective Heigth Sensor Resistance (Ω) (µm) Length (µm) (µm) Pt50 47.8 20 18019 0.2 Pt300 287 10 54170 0.2 Pt600 590 10 113207 0.2 4.4 Packaging Table 4.1: Overview of the temperature sensors. Shielding the interface electronic part of the chip from the corrosive effect of seawater, is as mentioned earlier the ’O’-ring and packaging. How is this built? The package or casing consists of three different layers (hereafter referred to as the lower, middle and upper layer) of laser 2 cut PMMA (PolyMethyl- MethAcrylate), that each have their own structure. While there are materials that are not as porous, and have better chemical properties, PMMA have the advantage that several can be fabricated within minutes once the actual structure is in place. Which have a higher priority than long term usage as far as testing purposes goes. Also PMMA can generally be used in the temperature area from -40 o C to 70 o C, as well as being electric isolating. So what do these layers look like, and what purpose does each serve? 2 Laser used is a SYNRAD laser
4.4. PACKAGING 37 Figure 4.11: Close up photography of a flex print. 1 mm 1.7 mm 11 mm 6.5 mm 66.5 mm Figure 4.12: Rough sketch of the middle layer of the encapsulation, sizes listed to give a clearer picture of actual size Figure 4.13: Pictures taken of the middle layer, to show what it looks like once fabricated, the layer is tilted slight on the picture to the right to compensate for the light. The middle layer as seen on figure 4.12 and 4.13 is where the chip is located, 4 areas are cut into the PMMA with a laser. The area with the
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 and 34: 3.2. THE POTENTIOSTAT 23 Reference
Page 35 and 36: 3.2. THE POTENTIOSTAT 25 Working El
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: 4.3. TEMPERATURE SENSOR 35 a Pt300,
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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