Prototyping of microfluidic systems with integrated ... - DTU Nanotech

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30 Polymer materials – mainly Topas Transmission (%) 100 80 60 40 20 0 200 400 600 800 1000 1200 1400 1600 1800 2000 Wavelength (nm) Figure 3.4: The visible and near infrared spectrum of Topas. A linear transmission is found in the visible wavelength area. The small decrease in transmission with a peak near 920 nm is found again in the waveguide measurements. Adapted from [33]. The refractive index of Topas changes with the norbonene content and the glass transition temperature as seen in Fig. 3.1. Pure polyethylene has a refractive index n = 1.49 at 633 nm and low Tg Topas grade 8007 has n = 1.5361, while high Tg grades have 1.5309 < n < 1.5320. This difference in refractive index between the 8007 grade and the other grades is used in the fabrication of all-Topas multilayer microfluidic systems with integrated waveguides, as described in chapter 5. The water absorption of Topas is significantly smaller than for the other standard polymers, as seen in Table 3.2. This fact is also of importance when regarding the optical properties of the polymers, since the deformation of a structure is minimised when the water absorption is small. In this manner, e.g. lens structures will deviate less from the original, dry state when exposed to water. 3.4.3 Chemical resistance As stated earlier, one of the problems in fabrication of microfluidic systems is the lack of compatibility of the structure with chemicals used in specific chemical reactions. One such incompatibility is that between ethanol, which is commonly used as solvent for many substances, and PMMA. Cracks and opacity in the structure occur within short time, often leading to fluidic leakages, and making optical measurements impossible.
3.4 Cyclic Olefin Copolymer (COC)/Topas 31 Table 3.2: Comparison of key material properties of Topas grade 5013 to those of commonly used types of PMMA, PC and PS. It is noted that the density of Topas is 10-20% lower than that of the other polymers, and that the water absorption is significantly lower. Data are taken from [31]. Value Property Topas PMMA PC PS Refractive index n (589 nm) 1.533 1.491 1.586 1.590 Transmission (%), thickness 3 mm >92 >92 >89 >88 Density (g/cm3 ) 1.02 1.19 1.2 1.1 Heat deflection temperature (℃) at 18.2 bar 120 85 120 80 Water absorption (% )
Page 1 and 2: Prototyping of Microfluidic Systems
Page 3 and 4: Preface This thesis is one of the r
Page 5 and 6: joining the substrate, optical laye
Page 7 and 8: Disse metoder inkluderer: • Mikro
Page 9 and 10: Many thanks to the collaborators in
Page 11 and 12: microfluidic systems. In Klavs Jens
Page 13 and 14: Contents Preface i Abstract ii Resu
Page 15 and 16: CONTENTS xiii 5 Optical waveguides
Page 17 and 18: Chapter 1 Introduction In the last
Page 19 and 20: 1.1 Downscaling 3 Figure 1.1: Scali
Page 21: 1.2 Prototyping of microfluidic sys
Page 24 and 25: 8 Theoretical aspects - microfluidi
Page 26 and 27: 10 Theoretical aspects - microfluid
Page 38 and 39: 22 Polymer materials - mainly Topas
Page 52 and 53: 36 Fabrication methods results are
Page 54 and 55: 38 Fabrication methods An impressiv
Page 56 and 57: 40 Fabrication methods Average roug
Page 58 and 59: 42 Fabrication methods a b c d e 1m
Page 60 and 61: 44 Fabrication methods Generally, t
Page 62 and 63: 46 Fabrication methods branch. Sec-
Page 64 and 65: 48 Fabrication methods and the heig
Page 66 and 67: 50 Fabrication methods Topas on Top
Page 68 and 69: 52 Fabrication methods Table 4.2: C
Page 70 and 71: 54 Fabrication methods Figure 4.8:
Page 72 and 73: 56 Fabrication methods that the str
Page 74 and 75: 58 Fabrication methods the excimer
Page 76 and 77: 60 Fabrication methods 500 µm 500
Page 78 and 79: 62 Fabrication methods wedge tests
Page 81 and 82: Chapter 5 Optical waveguides in Top
Page 83 and 84: 5.1 Waveguide fabrication 67 It sho
Page 85 and 86: 5.2 Propagation loss measurements 6
Page 87 and 88: 5.3 Thermal treatment of the surfac
Page 93 and 94: 5.4 Optical cuvette absorbance meas
Page 95 and 96: 5.4 Optical cuvette absorbance meas
Page 97 and 98:
5.5 A refractive index sensor 81 fr
Page 99 and 100:
5.5 A refractive index sensor 83 a
Page 101 and 102:
5.6 Summary 85 5.5.3 Improvements I
Page 103:
Until further notice, Chapter 6 is
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96 Discussion and outlook transpare
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References [1] A. Manz, N. Graber,
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REFERENCES 101 [20] David Walton an
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REFERENCES 103 [41] Kiha Lee and Da
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REFERENCES 105 prototyping of polym
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REFERENCES 107 [81] M. Grumann, J.
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Prototyping of microfluidic systems with integrated ... - DTU Nanotech

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