title: Versatile characterization of thiol-functionalized printed metal electrodes on flexible substrates for cheap diagnostic applications.
abstract: BACKGROUND
  Cheap, reliable, point-of-care diagnostics is a necessity for the growing and aging population of the world. Paper substrate and printing method, combined together, are the cheapest possible method for generating high-volume diagnostic sensor platforms. Electrical transduction tools also minimize the cost and enhance the simplicity of the devices.
  
  
  METHODS
  Standard surface characterization techniques, namely contact angle measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the growth of the organic thiol layers on top of the printed metal electrodes on paper substrates. The results were compared with those obtained by impedimetric electrical characterization method.
  
  
  RESULTS
  This article reports the fabrication and characterization of printed metal electrodes and their functionalization by organic layers on paper and plastic substrates for biosensing and diagnostic applications. Impedimetric measurement is proposed as a simple, yet elegant, method of characterization of the organic layer growth.
  
  
  CONCLUSIONS
  Very good correlation was observed between the results of organic layer growth from different measurement methods, justifying the use of paper as a substrate, printing as a method for fabricating metal and organic layers and impedance as a suitable measurement method for hand-held diagnostic devices.
  
  
  CONCLUSIONS
  This result paves the way for the fabrication of more advanced bio-recognition layers for bio-affinity sensors using a printing technology that is compatible with flexible and cheap paper substrates. This article is part of a Special Issue entitled Organic Bioelectronics - Novel Applications in Biomedicine.
authors.affiliation: Center of Excellence for Functional Materials, Laboratory of Physical Chemistry, Åbo Akademi University, Porthaninkatu 3, FI-20500 Turku, Finland. pihalain@abo.fi
authors.forename: Petri
authors.initials: P
authors.lastname: Ihalainen
authors.forename: Himadri
authors.initials: H
authors.lastname: Majumdar
authors.forename: Anni
authors.initials: A
authors.lastname: Määttänen
authors.forename: Shaoxia
authors.initials: S
authors.lastname: Wang
authors.forename: Ronald
authors.initials: R
authors.lastname: Österbacka
authors.forename: Jouko
authors.initials: J
authors.lastname: Peltonen
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D019719:Diagnostic Equipment; D004566:Electrodes; D008670:Metals / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods; D010209:Paper; D056951:Photoelectron Spectroscopy / Q000295:instrumentation / Q000379:methods; D010969:Plastics / Q000737:chemistry; D011327:Printing / Q000295:instrumentation* / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D008670:Metals; D010969:Plastics; D013438:Sulfhydryl Compounds