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

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46 CHAPTER 5. FABRICATION conducting glue. The final step in the packaging, will be to bond the 3 layers of PMMA together (the ’O’-ring is inserted here as well), this is accomplished by putting them in a oven at 115 o C for 1 hour, which will cause them to bond. To hold then layers in place, two pieces of metal are used as well as a screw clamp. Care should be taken not to put to much pressure on the PMMA with the screw clamp, nor to little. However applying less than needed pressure is preferable, as it can be put back into the oven, if the bonding have not taken place. While to much pressure can cause the chip to break (a closer look is taken on this problem in Chapter 6). Figure 5.10: Preparation for the oven. Top left: The screw clamp. Top right: The two pieces of metal that holds the PMMA, chip and flexprint in place and together. Bottom Left: The 3 layers of PMMA have been placed in the the metal holder. Bottom right: Screw clamp have been closed tightly around the metal holding the PMMA.
5.2. BACK-END PROCESSING 47 5.2.2 Ag to Ag/AgCl Ag has to be turned into AgCl. This can be done in several ways, one of the easier ways[44] however consists of using: 1. 0.1 M HCl 2. A flashlight battery. 3. A few centimeters of pure silver. Figure 5.11: Ag turned into Ag/AgCl. The packaged chip is dipped down into the HCl along with one end of the silver wire. While the battery is connected with the negative terminal to the silver wire and the positive to the Ag output on the flexprint. Slowly the Ag electrode will turn a light tan and then a dark brown, at which point it will have a suitable thick layer of AgCl. 5.2.3 Electrolyte and Membrane Finally the electrolyte and the membrane is added. The material used is Siloprene from Fluka-Chemie. It consists of 3 liquids Siloprene Crosslinking Agent K-11, Siloprene K 1000 and Hexane. All three liquids are dripped into the small hole on the device, where the chip is located, by using a syringe (The amounts used are of the order of 100:10:1 for Siloprene Crosslinking Agent K-11 : Siloprene K 1000 : Hexane). Finally the sensor is soaked in a liquid containing a large amount of Cl − ions (the time it needs to be soaked depends on the exact concentration, the higher the concentration is, the less time it needs. Care should be taken however if a strong acid is used, as it might damage the membrane) to add the electrolyte. Other membranes have been used with micro electrode oxygen sensor(such as Nafion[45]). However this was chosen, due to the recommendation and experiences of a professor at MIC.
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 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: 5.2. BACK-END PROCESSING 45 under e
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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