V16 Capillary effect and paper-based µF WS 23 PDF Lecture Notes

V16 V16 16.1 Capillary Effect 16.2 Paper-based Microfluidics Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 1 Contents V16 2 Contents 16.1 Capillary Effect 16.2 Pa...

V16 V16 16.1 Capillary Effect 16.2 Paper-based Microfluidics Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 1 Contents V16 2 Contents 16.1 Capillary Effect 16.2 Paper-based Microfluidics 16.1.1 Introduction 16.2.1 Introduction 16.1.2 Laplace Pressure 16.2.2 Fabrication Technologies 16.1.3 Young-Laplace Equation 16.2.3 Flow in Porous Material  Filling 16.1.4 Filling of Capillaries  Volume flow rate  Laminar Flow 16.2.4 Devices and Applications Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Learning Targets V16 Learning Targets  Capillary effect  Filling of channels  Laplace pressure and Young-Laplace equation  Paper-based microfluidics  Fabrication technologies  Operation mode of dipsticks Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 3 V16 16.1.1 Introduction to Capillary Effect Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 4 16.1.1 Introduction to Capillary Effect V16 https://de.wikipedia.org/ Capillary Effect θ < 90° θ > 90° Θ … Contact angle http://www.youtube.com/watch?v=UtRIk4TwQDQ N. Ramalingam: Biomed Microdevices (2009) 11:1007–1020 Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 5 16.1.1 Introduction to Capillary Effect Capillary Depression A … Adhesive force V16 Capillary Ascension Adhesive forces are attractive forces between unlike molecules. Adhesion causes the liquid to cling to the surface on which it rests K … Cohesive force Cohesive forces are intermolecular forces (such as those from hydrogen bonding and van der Waals forces) which cause a tendency in liquids to resist separation Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 6 16.1.1 Introduction to Capillary Effect V16 7 Capillary Ascension Glass  Hydrophilic channel/capillary walls  Adhesion forces are strong enough θ that water tends to spread, forming a thin film over, e.g., a glass surface  Increase of surface area, surface is stretched Water  Wetting causes  Curvature of surface  Increase of surface tension http://daten.didaktikchemie.uni-bayreuth.de/umat/benetzung/benetzung.htm Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 16.1.2 Laplace Pressure Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 8 16.1.2 Laplace Pressure V16 Gas  At flat surfaces, the tangential forces are canceled  In channels, meniscus is formed caused by 9 Liquid adhesive/cohesive forces at the channel walls  At curved surfaces, tangential forces are not canceled, F resulting in a net force to the concave side of the interface  Force is related to pressure (p = F / A)  Pressure / Force at the concave side is always higher than at the convex side Laplace Pressure is an Interface Pressure Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.2 Laplace Pressure V16 10 Laplace Pressure = Capillary Pressure Appearance of a pressure difference across an interface between two phases pLaplace  pnon  wetting phase  pwetting phase Laplace pressure Is the pressure difference between the non-wetting phase and the wetting phase Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.2 Laplace Pressure V16 11 pLaplace  pnon  wetting phase  pwetting phase System Wetting phase Water - Gas Water Water – Oil Water Gas – Oil Oil Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 12 16.1.3 Young-Laplace Equation Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.3 Young-Laplace Equation de.wikipedia.org V16 13 Young-Laplace Equation (1805) (independently developed) The Young-Laplace equation states that any curved liquid maintains a pressure r1 r1, r2 … σ ……. pLaplace  pnon  wetting phase  pwetting phase 1 1       r1 r2  de.wikipedia.org interface at equilibrium separating phase 1 from phase 2 Thomas Young (1773 – 1829) Pierre-Simon Laplace (1749 – 1827) Curvature radii in any two orthogonal directions The radii are algebraic quantities, which are positive if the center of the curvature lies within the phase at higher pressure and negative otherwise Surface tension Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.3 Young-Laplace Equation V16 14 Laplace Pressure = Capillary Pressure = Curvature Pressure pLaplace  pnon  wetting phase  pwetting phase 1 1       r1 r2  Laplace pressure describes the curvature of the meniscus The smaller the curvature radii, the higher the pressure difference across the interface r1, r2 … σ ……. Curvature radii in any two orthogonal directions Surface tension Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.3 Young-Laplace Equation V16 15 In Cylindrical Capillaries Curvature Radii can be Expressed by Capillary Radius R 1 1 pLaplace        r1 r2  In capillary r1 = r2 = R r pLaplace    pLaplace  2 R 2   cos C r Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 r1,r2,R… Curvature radius r …….... Capillary radius σ ………Surface tension 16.1.3 Young-Laplace Equation Laplace Pressure Cylindrical Capillary Rectangular channel with different side wall materials V16 16 pLaplace 1 1       r1 r2  pLaplace  pLaplace 2    cos C r  cos t  cos b cos l  cos  r      h w   w θt θl M. Zimmermann et al.: Lab Chip 7 119-125 (2007) A. Olanrewaju et al.: Lab Chip DOI: 10.1039/c8lc00458g Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 θb θr h 16.1.3 Young-Laplace Equation pLaplace  pnon  wetting phase  pwetting phase V16 17 pLaplace, cylinder 2    cos C  r Hydrophilic channel Hydrophobic channel pLaplace  0 * pLaplace  0 * M. Mahdhi et al: Polymers 14 2908 (2022) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 * Note that the sign is not consistently defined in the literature V16 18 16.1.4 Filling of Capillaries Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries Surface tension force Flift Fst    2  r V16 19 Capillary Ascension Capillary Action Water climbs the hydrophilic capillary because of surface tension force Fst Fst    2  r For a cylindrical capillary Lift force Flift is the vertical component of Fst 2r Flift  Fst  cos C Flift    2  r  cos C http://www.engineeringarchives.com/les_fm_capillaryeffect.html Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 ΘC …… Contact angle r …….... Capillary radius σ ………Surface tension 16.1.4 Filling of Capillaries Surface tension force Flift Fst    2  r V16 20 In equilibrium Fgrav  Flift Flift    2  r  cos C Fgrav  m  g  V    g    r 2  h    g Fgrav hmax 2    cos C    g r σ … Surface tension r … Capillary radius 2r θC.. Contact angle Fgrav Gravitation force ρ … Density A … Cross section http://daten.didaktikchemie.uni-bayreuth.de/umat/benetzung/benetzung.htm h … Height of water column Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries V16 21 Bond number Bo Surface tension force Flift Fst    2  r Bo  Gravitational force Fg Surfacetension force Fst Fst    2  r Flift    2  r  cos C Fg  W  m  g  V    g    r 2  h    g Fgrav In equilibrium Bo =1 2r hmax 2    cos C    g r https://bradroth.medium.com/the-bond-number-19d489c58f76 http://daten.didaktikchemie.uni-bayreuth.de/umat/benetzung/benetzung.htm Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 σ… r… θC.. W.. ρ… h… V... Surface tension Capillary radius Contact angle Gravitation force Density Height of water column Volume 16.1.4 Filling of Capillaries V16 22 Surface tension force Fst    2  r Force component which pushes the droplet The higher the Laplace pressure, the higher the pushing force Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries V16 23 Filling of Capillaries by Capillary Effect t1 < t2 R1 R2 Θ1 Cylindrical capillary pLaplace 1  2  Θ2 1 R1 < pLaplace 2  2  1 R2 The driving force (Laplace pressure) must be sufficient high to overcome the dynamic contact angle hysteresis Filling starts beyond the critical dynamic contact angle Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries V16 24 Filling Stop at a Channel Expansion pLaplace  2   cos C r  Contact angle ΘC increases by β  cos ΘC decreases  pLaplace decreases  Further filling is only possible when β additional pressure is applied to the channel (e.g. by a syringe pump) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries V16 25 How fast is capillary filling? Volume flow rate Q in cylindrical capillary dV   r 4  p Q  dt 8   L h … Distance covered by the fluid front σ … Surface tension θC.. Contact angle η … Viscosity t …. Time r …. Capillary radius L … Filling length Hagen-Poiseuille (1883) (1) The relationship between the liquid volume and height in the capillary is given by dV    r 2  dh (2) Pressure drop is given by Laplace pressure 2    cos C p r In cylindrical capillary T. Dang-Vu et al.: Physicochemical Problems of Mineral Processing 39 47-65 (2005) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 (3) 16.1.4 Filling of Capillaries (1) and (2) inserted in (3) V16 26 dL r    cos C  dt 4   L L h … Distance covered by the fluid front σ … Surface tension θC.. Contact angle η … Viscosity t …. Time r …. Capillary radius L … Filling length dL r    cos C  dt 4  Integration with initial condition h = 0 @ t = 0 L r    cos C t 2  Lucas-Washburn equation for horizontally adjusted capillary T. Dang-Vu et al.: Physicochemical Problems of Mineral Processing 39 47-65 (2005) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries L(t )  V16 27 r    cos C t 2  Lucas-Washburn equation for horizontally adjusted capillary Lucas-Washburn’s equation describes the climb of fluid flow through a cylindrical capillary of radius r as a function of the driving (Laplace) pressure The equation above holds for  No gravity  No external pressure E.W. Washburn: Phys. Rev. 17 273-283 (1921) R. Lucas: Kolloid-Zeitschrift 23 (1) 15-22 (1918) A. Hamaroui et al.: J. Colloid Interface Sci 250 415-421 (2002) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Edward W. Washburn (1881 - 1934) 16.1.4 Filling of Capillaries V16 28 Capillary Rise of Water in Vertical* Glass Capillary with r = 0.315 mm A. Hamaroui et al.: J. Colloid Interface Sci 250 415-421 (2002) * In this case, the LW equation is modified by gravitational forces (not discussed in the lecture) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries V16 29 How to achieve a constant flow rate over long time Q p R fluid for filling the capillary?  Flow rate Q depends on ∆p/Rfluid  Rfluid increases with filling length L For a rectangular channel (w < h) pLaplace R fluid cos t  cos b cos l  cos  r (  ) h w  1  5 h  h wd    1     12 6 w L     2 h 1 *  Flow rate drops down Requirements for a constant flow rate  Nearly constant Rfluid  High and constant ∆p * Linear approximation from Fourier series M. Zimmermann et al.: Lab Chip 7 119-125 (2007) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries V16 30 Constant Filling Flow Rate - Capillary Pump High and constant ∆p Nearly constant Rfluid serp  Serpentine channel with high Rfluid  Small capillaries serp Rfluid determines the overall Rfluid  Small w (while h is constant) M. Zimmermann et al.: Lab Chip 7 119-125 (2007) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.4 Filling of Capillaries https://www.youtube.com/watch?v=d-kXJzVntbg Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 31 V16 32 Conclusion Capillary effect  Most important for microfluidics  Enables spontaneous filling of capillaries/microchannels  Based on  Adhesive / cohesive forces in capillaries  Surface tension (force)  Laplace pressure  Large surface-to-volume-ratio in microchannels Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 33 16.2 Paper-based Microfluidics Microfluidic Paper-based Analytical Devices (µPADs) Lateral Flow Strips (LFSs) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 34 16.2.1 Introduction Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.1 Introduction V16 35 Paper  Cellulosic materials  Porous  Filter paper  Chromatographic paper are manufactured using high-quality cotton linter (short fiber) with a minimum α-cellulose content of 98 % Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.1 Introduction V16 36 Paper Parameters  Hydrophilic (in nature)  Capillary flow rate (capillary flow time*)  Surface area ratio of 50-200  Pore size (= inner area / projected area)  Porosity  Surface roughness  Thickness (> 50 µm)  Protein binding capacity  Preferred white color  Low electrostatic charge (for colorimetric tests) * time required for the sample to move along and saturate the paper with a defined length A. K. Yetisen et al.: Lab Chip 13 2210 (2013) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 37 16.2.2 Fabrication Technologies of Paper-based µF Devices Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies V16 38 Fabrication Principle To pattern hydrophilic-hydrophobic contrast on a sheet of paper in order to create micron-scale capillary channels on paper Hydrophobic Agents  Wax  Polystyrene  Paraffin  Resin  Ethyl cellulose  Printer varnish  Silicones  Cellulose esters A.W. Martinez et al: Angew Chem Int Ed Engl. 46(8) 1318–1320 (2007) X. Li et al.: Biomicrofluidics 6 011301 (2012) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies V16 39 Wax Screen Printing (Physical deposition)  Solid wax rubbed through a screen/stencil onto a paper sheet  Paper placed on a hot plate / oven  Wax melts and diffuses into the paper forming hydrophobic barriers   Low cost fabrication equipment Suffer from low reproducibility A. K. Yetisen et al.: Lab Chip 13 2210 (2013) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies Wax Screen Printing https://www.youtube.com/watch?v=kcdKxuYC8V8 Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 40 16.2.2 Fabrication Technologies V16 41 Wax Dipping (Physical deposition)  Iron mold (made by laser cutting)  Mold is pressed to the paper using a magnet  Dipping in wax (120 - 130 °C for 1 s)  Removing the mold   Low cost fabrication equipment  Suffer from inflexibility in patterning and low reproducibility A. K. Yetisen et al.: Lab Chip 13 2210 (2013) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies V16 42 Wax Printing (Physical deposition)  Paper is fed into a wax printer  Wax is used as ink  Processed by a heat cycle (hot plate or oven)  Completed within few minutes  Capable to produce high numbers of copies E. Carrilho et al.: Anal. Chem. 81 7091-7095 (2009) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies V16 43 Alkyl Ketene Dimer (AKD) Printing (Chemical modification)  Fiber surface is chemically modified by cellulose reactive agents  Reagents rend to react with OH- groups of cellulose  Results in hydrophobicity of cellulose fibers (contact angle 110°-125°)  Carried out with ink-jet printers  Followed by 100 °C treatment for 8 min A. K. Yetisen et al.: Lab Chip 13 2210 (2013)    Hydrophobic areas are invisible Paper retains flexibility Alkyl ketene dimer is cheap Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies Flexographic Printing (physical deposition) V16 44  Roll-to-roll production  Paper fixed to impression roll  Polystyrene in toluene or xylene (< 10 wt. %) solution applied to ink tray  Solution transferred to anilox roll  Excess solution be removed by blade  Anilox roll transfers solution to printing plate comprising relief patterns  Printing of patterns on paper substrate   Existing manufacturing equipment high throughput (60 m/min) J. Olkkonen et al.: Anal. Chem. 82 10246-10250 (2010) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.2 Fabrication Technologies Paper-based Microfluidics Cut in Glass Fiber https://www.youtube.com/watch?v=59oj_pT3R5U Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 45 V16 46 16.2.3 Flow in Porous Material Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.3 Filling of Capillaries in Porous Material V16 47 Filling of Capillaries in Porous Material Lucas-Washburn Lucas-Washburn for porous material L… σ… θC.. r… rm.. η… t …. r    cos C L(t )  t 2  rm    cos C L(t )  t 2  Filling length Surface tension Contact angle Capillary radius Average pore radius Viscosity Time  Non-limited reservoir  Constant average pore size rm  Constant channel width 2r  No impurities E.W. Washburn: Phys. Rev. 17 273-283 (1921) S. Mendez et al.: Langmuir 26 (2) 1380-1385 (2010) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.3 Volume Flow Rate in Porous Material V16 48 Volume Flow Rate in Porous Material d Q  A K  L Darcy‘s law Fluid flows from high pressure to low pressure Henry Darcy (1803 - 1858) ∆d din d out Q… Volume flow rate A … Column cross-sectional area L … Length of the column K … Hydraulic conductivity Δd … Head https://fracfocus.org/groundwater-protection/fluid-flow-subsurface-darcys-law Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.3 Volume Flow Rate in Porous Material ∆d din d out V16 49 d Q  A K  L Darcy‘s law  p   L Darcy‘s law Refined by Morris Muskat Q  A Q A… L… K… Δd.. κ …. η.... Δp.. g… Flow rate Cross-section Length of column Hydraulic conductivity Head Permeability of porous material Viscosity Pressure difference Gravitational acceleration With  g K  Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 p    g  h 16.2.3 Laminar Flow in Porous Material V16 50 Laminar flow in paper https://www.youtube.com/watch?v=wIG2bZNREHc https://www.youtube.com/watch?v=R37HCT6I6gI Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 51 16.2.4 Devices and Applications Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 52 Diagnostic Dipsticks Colorimetric Detection Method Are also known as  Test strips  Lateral Flow Test (LAT) A. K. Yetisen et al.: Lab Chip 13 2210 (2013) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 53 On-Demand Devices  Paper areas without pre-deposited reagents  Depending on the samples to be tested, the detection reagents are chosen and introduced into the device by users prior to the test Wax-printed 384-zone paper plate after application of several dyes X. Li et al.: Biomicrofluidics 6 011301 (2012) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 54 Complete Devices by integrating indication reagents into the detection zones of the devices Helen Murray Free (Feb 20, 1923 – May 2, 2021) * Developed by Helen Murray Free 1956 @ Miles Laboratories, now Bayer AG https://www.nytimes.com/2021/05/03/science/helen-murray-free-dead.html X. Li et al.: Biomicrofluidics 6 011301 (2012) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 New York Times, May 3, 2021 Urine analysis by dipstick* 16.2.4 Devices and Applications V16 55 Colorimetric Detection Method  Enzymatic or molecular dyes for detection Leucocytes Nitrites Urobilinogen Protein pH Blood (hematuria) Specific Gravity Ketones Bilirubin Glucose  Visually assessed by eye for  Yes/No answers  Semi-quantitative detection with help of calibration chart   Most used Urine analysis dipstick  Inhomogeneous color distribution on the pad area Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 56 Quick Test for SARS-CoV-2 Virus Detection a) Test strip positive sample comprises SARSCoV-2 antigens c) When passing the conjugate pad during lateral flow, gold nanoparticles as a conjugate, which are labeled with monoclonal antibodies, will be released and partly bound to the antigen, forming a conjugate complex https://antigentest.bfarm.de/ords/antigen/r/antigentests-auf-sars-cov-2/liste-derantigentests?session=14493704434648&tz=1:00 Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 T C G.A. Posthuma-Trumpie et al.: Anal. Bioanal. Chem. 393 569-582 (2009) b) Sample is applied to the inlet. A 16.2.4 Devices and Applications V16 57 Quick Test for SARS-CoV-2 Virus Detection d) When passing the test line T (coated against the antigen) the complex is captured resulting in coloring e) When passing the line C, the gold particles labeled without the SARSCoV-2 antigen are captured by control line C resulting in coloring  Three types of antibodies are needed  Gold nanoparticles needed only to color the pads https://antigentest.bfarm.de/ords/antigen/r/antigentests-auf-sars-cov-2/liste-derantigentests?session=14493704434648&tz=1:00 Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 T C G.A. Posthuma-Trumpie et al.: Anal. Bioanal. Chem. 393 569-582 (2009) with a second capture antibody 16.2.4 Devices and Applications Quick Test for Pregnancy https://www.youtube.com/watch?v=lxi1oEQ7Hdw https://www.youtube.com/watch?v=uVaFbzJP6cE … and many other videos on youtube Info for Gold Labeling https://www.youtube.com/watch?v=PoOOC2qv0PI Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 58 16.2.4 Devices and Applications V16 59 Drugs COC.. Cocaine MET … Methamphetamine THC... Marihuana K2 …. Spice (synthetic cannabinoids) AMP… Amphetamine www.ultimed.de Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications Hematocrit Portion of erythrocytes in the blood volume represents 90% of blood cells Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 60 16.2.4 Devices and Applications V16 61 Electrochemical Detection Method For Glucose / Diabetes Monitoring Can be measured as an electrochemical reaction at electrodes https://en.wikipedia.org/wiki/Glucose_oxidase#/media/File:Glucose_oxidase_rxn.svg Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 62 Paper-based test strip for glucose sensing using commercial electrochemical reader  Need electrodes  Electrodes are screen printed  Using graphite and silver inks  Insensitive to local light conditions  High sensitivity (in nM range)  Quantification of analyte  Often used Z. Nie et al.: Lab Chip 10 3163-3169 (2010) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 stored dried reagents 16.2.4 Devices and Applications ReliOn Ultima Test Strip V16 63 Freestyle Test Strip https://hackaday.io/ Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 64 Electrochemical blood-glucose strips with analyzed blood volumes of ca. 1 μL or less. From left to right: One Touch Ultra, Arkray, Ascensia Contour, BD Test Strip, Free-Style, Precision Xtra, TrueTrack Smart System, and Accuchek, Aviva. A. Heller, B. Feldman: Chem. Rev. 108 2482-2505 (2008) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications Read-out Devices for Electrochemical Sensing www.3in1.si V16 65 A. K. Yetisen et al.: Lab Chip 13 2210 (2013) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications V16 66 Forecast for Glucose Meters https://market.us/report/bloodglucose-meters-market/ https://www.grandviewresearch.com/sectorreport/blood-glucose-meters-industry-data-book CAGR … Compound Annual Growth Rate Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.2.4 Devices and Applications Paper-based Microfluidic Valves Reservoir Reaction chamber Switch X. Li et al.: Anal. Chem. 80 9131-9134 (2008) Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 67 16.2.4 Devices and Applications Paper-based Analytical Device Fabricated with Origami https://www.youtube.com/watch?v=C7O_AxsgtmY Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 68 16.2.4 Devices and Applications Working principle https://www.youtube.com/watch?v=WYi-C3jGwKA Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 69 16.2.4 Devices and Applications V16 70 Paper-based Microfluidics Advantages Disadvantages  Low-cost fabrication  Ineffective sample consumption  Robust  High limit-of-detection  Easy to use  Low sample volumes  Simple detection methods  Applicable in developing countries Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 Conclusion V16 71 Conclusion  Paper-based microfluidic  Commercialized  Cheap dipsticks are useful for diagnostics in developing countries Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 72 One Minute Paper 1. What was the most important topic you understood? 2. What was the topic you didn‘t catch? Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 16.1.1 Introduction to Capillary Effect https://iopscience.iop.org/chapter/978-1-6817-4297-7/bk978-1-6817-4297-7ch3.pdf Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 73 16.1.2 Laplace Pressure https://www.youtube.com/watch?v=ZCd_0sz2fVY Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 74 16.2.4 Devices and Applications https://www.youtube.com/watch?v=p7gDKRlV4II Lecture „Microfluidic Systems - Bio-MEMS“ – Capillary Effect and Paper-based Microfluidics Prof. Dr.-Ing. Uwe Schnakenberg | Institute of Materials in Electrical Engineering 1 | WS 23 V16 75