Markus Dankerl

Year: 2012

The diamond / electrolyte interface and its application for cell interfacing

Biosensors and bioelectronic applications have gained increasing interest in recent years, opening the way to the search of new materials which can fully exploit the potential of these applications. Diamond has quite a number of interesting properties like chemical and electrochemical stability in electrolytes (physiological media) as well as biocompatibility, the combination of which makes this material exceptionally well suited for applications in biochemistry and medicine. Particularly intriguing is the establishment of a surface conductivity in undoped but hydrogen terminated diamond. This surface conductivity is provided by a two-dimensional hole gas (2DHG) in a triangular potential well created by band bending beneath the diamond surface.

My research focuses on the interface between this p-type surface conductive diamond and electrolytes and the applications of this system for biosensing and interfacing with living cells. The surface conductivity of diamond can be controlled by shifting the surface potential of the diamond. This allows for the design of in-plane solution gate controlled field effect transistors (SGFETs). As the pH influences the surface potential as well, these SGFETs can be used as pH sensors. The properties and origin of this pH sensitivity as well as the properties of the SGFETs in general are investigated with electrochemical (e.g. cyclic voltammetry, impedance spectroscopy) as well as electronic characterization methods.

The electrical transport within the 2DHG is investigated using the Hall-effect and investigating the contributions of the carrier concentration and the mobility to the overall conductivity. The possibility of controlling the carrier concentration is a significant advantage. This is a fundamental investigation of the transport mechanism at this interface, where localisation of carriers and different scattering mechanisms determine the transport properties.

The understanding of the diamond/electrolyte interface and the capability to control it, are used to interface with biological cells. To this end we have produced arrays of SGFETs, whose active area are functionalized to provide favorable conditions for cell growth. Chemistry and photochemistry are employed together with photolithography to fabricate the functionalized SGFETs. The functionalization is investigated with fluorescence microscopy, AFM, and electrochemical techniques. As a next step, we will attempt the controlled cell growth and the recording of cell action potentials. Finally we hope to record the signals from rat retina cells.


Figure 1: Schematics of a diamond SGFET




6th EU FP; project: Diamond to Retina Artificial Micro-Interface Structures (DREAMS)


Charge state manipulation of qubits in diamond

Nature Communications 3, 729 (2012)

B. Grotz | M. Hauf | M. Dankerl | B. Naydenov | S. Pezzagna | J. Meijer | F. Jelezko | J. Wrachtrup | M. Stutzmann | F. Reinhard | J. A. Garrido

Online Reference

Diamond solution-gated field effect transistors: Properties and bioelectronic applications

physica status solidi (a)

M. Dankerl | M. Hauf | M. Stutzmann | J. A. Garrido

Online Reference

Solid polyelectrolyte-gated surface conductive diamond field effect transistors

Applied Physics Letters 100, 023510 (2012)

M. Dankerl | M. Tosun | M. Stutzmann | J. A. Garrido

Online Reference

Chemical control of the charge state of nitrogen-vacancy centers in diamond

Phys. Rev. B 83, 081304(R) (2011)

M. Hauf | B. Grotz | B. Naydenov | M. Dankerl | S. Pezzagna | J. Meijer | F. Jelezko | J. Wrachtrup | M. Stutzmann | F. Reinhard | J. A. Garrido

Online Reference

Hydrophobic Interaction and Charge Accumulation at the Diamond-Electrolyte Interface

Physical Review Letters 106, 196103 (2011)

M. Dankerl | A. Lippert | S. Birner | U. Stützel | M. Stutzmann | J. A. Garrido

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Graphene Solution-Gated Field-Effect Transistor Array for Sensing Applications

Advanced Functional Materials 20, 3117–3124 (2010)

M. Dankerl | M. Hauf | A. Lippert | L. Hess | S. Birner | I. D. Sharp | A. Mahmood | P. Mallet | J. Y. Veuillen | M. Stutzmann | J. A. Garrido

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Low-frequency noise in diamond solution-gated field effect transistors

Applied Physics Letters 97, 093504 (2010)

M. Hauf | L. Hess | J. Howgate | M. Dankerl | M. Stutzmann | J. A. Garrido

Online Reference

Diamond transistor array for extracellular recording from electrogenic cells

Adv. Funct. Mater. 19, 2915–2923 (2009)

M. Dankerl | B. Hofmann | S. Eick | M. Hauf | S. Ingebrandt | A. Offenhäuser | M. Stutzmann | J. A. Garrido

Online Reference

Electronic transport at the interface between diamond and aqueous electrolyte

DPG Fruehjahrstagung, Dresden, Germany

M. Dankerl | U. Stützel | A. Lippert | M. Stutzmann | J. A. Garrido

Resolving the controversy on the pH sensitivity of diamond surfaces


M. Dankerl | A. Reitinger | M. Stutzmann | J. A. Garrido

Online Reference

The surface conductivity at the Diamond/Aqueous electrolyte interface


J. A. Garrido | A. Haertl | M. Dankerl | A. Reitinger | M. Eickhoff | A. Helwig | G. Muller | M. Stutzmann

Online Reference

TUM Technische Universität München TUM Technische Universität München Physik Department Elektrotechnik und Informationstechnik TUM Technische Universität München

Events & News

17 Jan 2018

ERC Consolidator Grant for Gregor Koblmüller   more

10 Aug 2017

Best Poster Awards for Ganpath Veerabathran and Alexander Andrejew at iNOW 2017   more

27 Jun 2017

Best Poster Award at Nanowire Week for Jochen Bissinger   more

15 Mar 2017

Dr. Kai Müller admitted to the “Junges Kolleg” of the Bavarian Academy of Sciences   more

27 Feb 2017

Two-photon pulses from a single two-level system   more


January 26, 2018

Reliability of hexagonal boron nitride dielectric stacks for CMOS applications   more

January 23, 2018

Helical states, spin-orbit coupling, and phase-coherent transport in InAs nanowires   more

January 16, 2018

New insights into novel (and conventional) materials using polarization-sensitive infrared magneto-spectroscopy   more