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@PHDTHESIS{Kireev:830124,
      author       = {Kireev, Dmitry},
      title        = {{G}raphene {D}evices for {E}xtracellular {M}easurements},
      volume       = {155},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-03703},
      isbn         = {978-3-95806-265-8},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {IX, 169 S.},
      year         = {2017},
      note         = {RWTH Aachen, Diss., 2017},
      abstract     = {Recording extracellular potentials from electrogenic cells
                      (especially neurons) is the hallmark destination of modern
                      bioelectronics. Graphene is a promising material, which
                      possesses features relevant to bioelectronics applications.
                      Graphene-based electrode arrays (GMEAs) and more complicated
                      graphene field effect transistors (GFETs) comprise a new
                      type of bioelectronic device application. Biocompatibility,
                      stability, excellent and unique electronic properties,
                      scalability, and pure two-dimensional structure make
                      graphene the perfect material for bioelectronic
                      applications. The advantages of graphene as part of such
                      devices are numerous: from a general exibility and
                      biocompatibility to the unique electronic properties of
                      graphene. In this work, the GMEAs and GFETs are fabricated
                      using CVD-grown graphene and a scalable cleanroom-based
                      technology. The devices are fabricated on both rigid and
                      exible substrates. In order to ensure a wafer-scale
                      fabrication of the devices, a new high throughput graphene
                      transfer technique is established. The technique allows me
                      to use just 4 cm$^{2}$ of CVD-grown graphene to fabricate a
                      whole 4-inch wafer with 52 chips on it. Rigid GFETs,
                      fabricated on different substrates, with a variety of
                      channel geometries (width/length), reveal a linear relation
                      between the transconductance and the width/length ratio. The
                      area normalized electrolyte-gated transconductance is in the
                      range of 1-2 mS V$^{−1}$ $\Box$, and does not strongly
                      depend on the substrate. Influence of the ionic strength on
                      the transistor performance is investigated as a part of the
                      work. Double contacts are found to decrease the effective
                      resistance and the transfer length, but do not improve the
                      transconductance. An electrochemical annealing/cleaning
                      effect is investigated and proposed to originate from the
                      out-of-plane gate leakage current. The devices are used as a
                      proof-of-concept for bioelectronic sensors, recording
                      external potentials from $\textit{ex vivo}$ heart tissue and
                      $\textit{in vitro}$ cardiomyocyte-like cells (HL-1). Via
                      multichannel measurements we are able to record and analyze
                      both difference in action potentials as well as their
                      spatial propagation through the chip. The recordings show
                      distinguishable action potentials with a signal to noise
                      ratio over 14 from $\textit{ex vivo}$ tissue and over 6 from
                      the cardiac-like cell line $\textit{in vitro}$. Furthermore,
                      I accomplished $\textit{in vitro}$ recordings of neuronal
                      signals with a distinguishable bursting activity for the
                      first time. [...]},
      cin          = {ICS-8},
      cid          = {I:(DE-Juel1)ICS-8-20110106},
      pnm          = {552 - Engineering Cell Function (POF3-552)},
      pid          = {G:(DE-HGF)POF3-552},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2017121302},
      url          = {https://juser.fz-juelich.de/record/830124},
}