Data Acquisition and Data Analysis in Skin Measurements Zhang Xu School of Engineering London South Bank University Supervisors: Dr. Perry Xiao Submitted: April 2017 To my Parents I Content Content ......................................................................................................... II Acknowledgement ......................................................................................... V Abstract ....................................................................................................... VI Chapter 1 Introduction and Skin Research Review .................................. 1 1.1 Skin Histology ........................................................................................................ 1 1.1.1 The Epidermis ................................................................................................................ 2 1.1.2 The Dermis .................................................................................................................... 4 1.1.3 The Subcutaneous Tissue .............................................................................................. 5 1.1.4 Skin Functions .......................................................................................................... 6 1.2 Skin Hydration ........................................................................................................ 6 1.2.1 Skin Hydration ............................................................................................................... 6 1.2.2 Water Concentration Profile and TEWL ........................................................................ 7 1.2.3 The Water in Stratum Corneum .................................................................................... 8 1.3 Latest Skin Measurement Technologies ................................................................. 8 1.3.1 Skin Conductance Measurement Technologies ............................................................. 8 1.3.2 Trans-Epidermal Water Loss (TEWL) Measurement.................................................... 11 1.3.3 Infrared Technologies for Skin Measurement ............................................................. 14 1.3.4 Skin Penetration Measurements ................................................................................. 16 1.3.5 Photothermal Technologies ........................................................................................ 18 1.4 Summary and Research Objectives ...................................................................... 20 1.5 Organization of the Thesis .................................................................................... 21 Chapter 2 Skin Measurement Instruments Overview .............................. 23 2.1 OTTER ................................................................................................................. 23 2.2 AquaFlux .............................................................................................................. 24 2.3 Epsilon Permittivity Imaging System ................................................................... 26 2.4 Corneometer ......................................................................................................... 28 2.5 Moisture Checker ................................................................................................. 29 2.6HydraTest ............................................................................................................... 30 2.7ProScopeHR2 Digital Microscope ........................................................................ 31 2.8 Summary ............................................................................................................... 32 Chapter3 Mathematical Modeling of OTTER ........................................ 33 3.1 Mathematical Modelling for OTTER ................................................................... 33 3.2 Enhanced Segmented Least Squares (SLS) Fitting Algorithm ............................. 38 3.3 Signal De-noising ................................................................................................. 40 3.4 Fast Fourier Transform ......................................................................................... 43 3.5 Summary ............................................................................................................... 46 II Chapter 4 Development of OTTER Data Acquisition and Data Analysis Program ...................................................................................................... 47 4.1 OTTER Software Specification ............................................................................ 47 4.2 PicoScope Technology and Software ................................................................... 48 4.2.1 Overview of Picoscope 4000 series PC oscilloscope .................................................... 48 4.2.2 Basic Specifications of PicoScope 4000 series ............................................................. 50 4.2.3 Overview of Picoscope2200A PC oscilloscope ............................................................. 50 4.2.4 Basic specifications of PicoScope2204 ........................................................................ 51 4.3 Visual Studio software .......................................................................................... 52 4.4 MATLAB Dynamic-link Library .......................................................................... 53 4.5 Structure of the new OTTER Data Acquisition and Data Analysis program ....... 54 4.5.1 Overall Design ............................................................................................................. 54 4.5.2 Graphical User Interface (GUI) .................................................................................... 54 4.5.3 Data Analysis Libraries ................................................................................................ 56 4.6 Functions of the New OTTER Program ............................................................... 64 4.6.1 "Real Time" View ........................................................................................................ 64 4.6.2"Measurement" View .................................................................................................. 68 4.7 Opto-Thermal Multiple Wavelength and Depth Resolved Detection in vivo-skin measurements ............................................................................................................. 71 4.7.1 Multiple Wavelength Detection .................................................................................. 71 4.7.2 Depth Resolved Profiles .............................................................................................. 77 4.7.3 Skin Characterization by Soap Washing ...................................................................... 82 4.7.4 3D Depth Profiling ....................................................................................................... 84 4.8 Summary ............................................................................................................... 85 Chapter 5 Skin Hydration and Solvent Penetration Measurements ........ 87 5.1 Skin Instrumentation Evaluation Measurements .................................................. 87 5.1.1 Repeatability of Different Instruments ........................................................................ 87 5.1.2 Correlations of Different Skin Instruments .................................................................. 90 5.2 Skin Damage Measurements by Multiple Devices ............................................... 95 5.3 Skin Tape Stripping Measurements by Multiple Devices ................................... 100 5.4 Skin Irritations by SLS ....................................................................................... 104 5.5 Capacitive Imaging Occlusion Effects ................................................................ 112 5.6 Effect of Soap Washing ...................................................................................... 120 5.7 Solvent Penetration ............................................................................................. 125 5.7.1 In-vitro Solvents Penetration .................................................................................... 125 5.7.2 In-vivo Skin Solvent Penetration................................................................................ 127 5.8 Summary ............................................................................................................. 130 Chapter 6 Conclusions and Future Work .............................................. 132 6.1 Conclusions .................................................................................................................. 132 6.2 Future Work ................................................................................................................. 134 Reference ................................................................................................... 136 Publications ............................................................................................... 147 Appendix ................................................................................................... 149 III Appendix I: OTTER C# main program .................................................................... 149 Appendix II: DLL Libraries ...................................................................................... 245 IV Acknowledgement First, I wish to express my