Downloaded from orbit.dtu.dk on: Oct 09, 2021 Pyrolytic carbon electrodes for bioelectrochemical applications Hassan, Yasmin Mohamed Publication date: 2018 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Hassan, Y. M. (2018). Pyrolytic carbon electrodes for bioelectrochemical applications. DTU Nanotech. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Pyrolytic carbon electrodes for bioelectrochemical applications Yasmin Mohamed Hassan PhD Thesis May2018 Pyrolytic carbon electrodes for bioelectrochemical applications Yasmin Mohamed Hassan Ph.D. Thesis May 2018 Main supervisor: Assoc. Prof. Stephan Sylvest Keller Co-supervisor: Postdoc Claudia Caviglia Preface This thesis is submitted as partial requirement for obtaining a Ph.D. degree from the Technical University of Denmark (DTU). The project was funded by the Young Investigator Program of the Villum Foundation (project no. VKR023438). The research was carried out in the Department of Micro- and Nanotechnology (DTU Nanotech) from May 2015 to May 2018. The Ph.D. was supervised by Assoc. Prof. Stephan Sylvest Keller and co-supervised by postdoc Claudia Caviglia. Kongens Lyngby, 1st May, 2018 Yasmin Mohamed Hassan Contents Abstract ............................................................................................................................ iv Resumé ............................................................................................................................. v Acknowledgements ......................................................................................................... vi List of abbreviations ...................................................................................................... viv List of publications ........................................................................................................ xiii Contributions to the papers ............................................................................................ xiii List of conference contribution ..................................................................................... xiv 1. Introduction ................................................................................................................ 1 1.1 Motivation .............................................................................................................. 1 1.2 Scope of the thesis .................................................................................................. 3 1.3 Organization of the thesis ....................................................................................... 4 2. Pyrolytic carbon electrode fabrication ..................................................................... 6 2.1 Carbon allotropes and properties............................................................................ 6 2.2 Pyrolytic carbon electrodes .................................................................................... 9 2.3 Pyrolysis ............................................................................................................... 10 2.3.1 Pyrolysis process ........................................................................................... 10 2.3.2 Polymer precursors ....................................................................................... 11 2.3.3 Pyrolysis temperature ................................................................................... 13 2.3.4 Gas composition ........................................................................................... 13 2.3.5 Heating rate ................................................................................................... 14 2.3.7 Dwell time ..................................................................................................... 14 2.3.8 Number of temperature steps ........................................................................ 15 2.4 Design of experiments .......................................................................................... 15 2.5 2D carbon electrode fabrication ........................................................................... 18 2.5.1 Chip design ................................................................................................... 18 2.5.2 Standard UV photolithography ..................................................................... 19 2.5.3 Colloidal templating ..................................................................................... 21 2.5.4 Etching .......................................................................................................... 25 2.5.5 Colloidal lithography .................................................................................... 27 3. Material characterization and analysis .................................................................. 29 3.1 Electrical measurements ....................................................................................... 29 3.2 Raman spectroscopy ............................................................................................. 31 3.3 Scanning electron microscopy (SEM).................................................................. 34 4. Electrochemical characterization ............................................................................ 36 i 4.1 Electrochemical cell ............................................................................................. 36 4.2 Electrodes configuration and electrochemical setup ............................................ 41 4.2 Cyclic voltammetry .............................................................................................. 43 4.3 Square wave voltammetry .................................................................................... 46 4.4 Electrochemical impedance spectroscopy ............................................................ 47 4.5 Chronoamperometry............................................................................................. 53 5. Monitoring bone cell differentiation on 2D pyrolytic carbon microelectrodes .. 55 5.1 Introduction .......................................................................................................... 55 5.2 The bone ............................................................................................................... 56 5.2.1 Bone tissue .................................................................................................... 56 5.2.2 Osteoporosis .................................................................................................. 59 5.3 In vitro cell-based viability assays ....................................................................... 60 5.4 Electrochemical impedance spectroscopy for cell monitoring ............................ 62 5.4.1 Introduction ................................................................................................... 62 5.4.2 Basic principle of ECIS ................................................................................ 63 5.4.3 Cell-electrode impedance models ................................................................. 64 5.4.4 Data analysis and cell index .......................................................................... 66 5.5 2D pyrolytic carbon electrodes for cell-based impedance sensing ...................... 66 5.6 Electrochemical detection of ALP activity of Saos-2 cells .................................. 69 5.6.1 Alkaline phosphatase .................................................................................... 69 5.6.2 Alkaline phosphatase detection techniques .................................................. 71 6. Monitoring of 3D cell cultures ................................................................................. 74 6.1 Introduction .......................................................................................................... 74 6.2 3D cell culture models.......................................................................................... 75 6.3 Monitoring cell fate in 3D in vitro models ........................................................... 76 6.4 3D pyrolytic carbon pillar electrodes ................................................................... 79 7. 3D pyrolytic carbon electrodes in miniaturized biophotovoltaic systems ........... 82 7.1 Introduction .......................................................................................................... 82 7.2 Energy generation using photosynthetic organisms ............................................. 83 7.3 Photocurrent generation from cyanobacterial cells .............................................. 85 7.4 Electrospinning on 3D pillar electrodes ............................................................... 88 8. Conclusions and outlook .........................................................................................