---
OA_place: publisher
_id: '22684'
abstract:
- lang: eng
text: "Contact electrification (CE) is a simple yet elusive phenomenon that occurs
when two materials come into contact and separate, leaving behind net electrical
charge. Despite its ubiquity, the microscopic origin of CE remains unclear. In
this thesis, we investigate CE from three complementary perspectives: developing
a quantitative method to measure charge at the nanoscale, exploring the dynamic
behavior of charge on insulating surfaces, and uncovering the role of mechanical
history in forming a triboelectric series.\r\n\r\nIn the first part, we establish
a rigorous framework for converting qualitative Kelvin probe force microscopy
(KPFM) voltage maps into quantitative charge density distributions. Using finite
element method (FEM) simulations, we determine the point-spread function of the
KPFM tip–sample geometry and demonstrate that the true surface charge can be reconstructed
by numerical deconvolution. This procedure enables the recovery of both the magnitude
and sign of charge density with high fidelity, resolving nanoscale features that
are otherwise obscured. Applying the method to contact-charged SiO$_2$ surfaces,
we show that existing analytical approximations, such as parallel plate or spherical
models, can miscalculate charge magnitude by orders of magnitude. Our hybrid FEM/KPFM
approach therefore provides a fast and general method to convert qualitative KPFM
signals into quantitative charge data, enabling nanoscale charge mapping under
realistic experimental conditions.\r\n\r\nIn the second part, we study the temporal
stability of CE-induced charges and identify the key material factors that determine
whether KPFM can capture meaningful charge patterns. Through time-resolved experiments
combining a custom-built transfer system with both microscopic and macroscopic
measurements, we demonstrate that only the best insulators, such as SiO$_2$, preserve
CE charge long enough for stationary imaging. For less conductive polymers, such
as PDMS, charge decays within the duration of a single KPFM scan due to bulk conduction.
Using a simple capacitor-based model, we reproduce the observed decay dynamics
and confirm that the transferred charge decays characteristic to the sample's
bulk conductivity. Further, we always observe homogeneous charge transfer.\r\n\r\nIn
the third part, we address the question: can we form a triboelectric series with
identical materials? Using controlled repetitive contact experiments, we show
that nominally identical materials can progressively order themselves into a triboelectric
series, where surfaces with more contact history charge negatively relative to
fresher ones. By constructing a minimal model based on this ``contact bias'',
we replicate the evolution from random to ordered charging observed in experiments.
Supporting surface analyses, including atomic force microscopy, reveal that repeated
contact induces nanoscale morphological changes, suggesting a mechanism tightly
coupled to mechanical strain. These results highlight the crucial role of surface
history and nanoscale mechanics in dictating charge transfer, motivating further
exploration of mechanisms such as mechanochemical bond cleavage and flexoelectric
polarization."
acknowledged_ssus:
- _id: NanoFab
- _id: ScienComp
- _id: LifeSc
- _id: M-Shop
- _id: EM-Fac
acknowledgement: "This project has received financing from the European Research Council
grant agreement\r\nno. 949120 under the European Union’s Horizon 2020 research and
innovation programme.\r\nThis research was supported by the Scientific Service Units
of The Institute of Science\r\nand Technology Austria (ISTA) through resources provided
by the Miba Machine Shop, the\r\nNanofabrication Facility, the Lab Support Facility,
the Scientific Computing Facility and the\r\nElectron Microscopy Facility. We thank
Florian Stumpf from Park Systems for useful discussions\r\nand support with scanning
probe microscopy. We thank Joaquin Garcia-Suarez and Guillaume\r\nAnciaux for the
suggestion to look into the roughness power spectral density. We thank\r\nIrina-Malina
Strugaru for help with testing the device for Young’s modulus measurements.\r\n"
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Felix
full_name: Pertl, Felix
id: 6313aec0-15b2-11ec-abd3-ed67d16139af
last_name: Pertl
orcid: 0000-0003-0463-5794
citation:
ama: Pertl F. Experimental probing of nanoscale charge features and surface morphology
changes during tribocharging. 2026. doi:10.15479/AT-ISTA-22684
apa: Pertl, F. (2026). Experimental probing of nanoscale charge features and
surface morphology changes during tribocharging. Institute of Science and
Technology Austria. https://doi.org/10.15479/AT-ISTA-22684
chicago: Pertl, Felix. “Experimental Probing of Nanoscale Charge Features and Surface
Morphology Changes during Tribocharging.” Institute of Science and Technology
Austria, 2026. https://doi.org/10.15479/AT-ISTA-22684.
ieee: F. Pertl, “Experimental probing of nanoscale charge features and surface morphology
changes during tribocharging,” Institute of Science and Technology Austria, 2026.
ista: Pertl F. 2026. Experimental probing of nanoscale charge features and surface
morphology changes during tribocharging. Institute of Science and Technology Austria.
mla: Pertl, Felix. Experimental Probing of Nanoscale Charge Features and Surface
Morphology Changes during Tribocharging. Institute of Science and Technology
Austria, 2026, doi:10.15479/AT-ISTA-22684.
short: F. Pertl, Experimental Probing of Nanoscale Charge Features and Surface Morphology
Changes during Tribocharging, Institute of Science and Technology Austria, 2026.
corr_author: '1'
date_created: 2026-08-12T09:44:40Z
date_published: 2026-08-12T00:00:00Z
date_updated: 2026-08-27T11:42:44Z
day: '12'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: ScWa
doi: 10.15479/AT-ISTA-22684
doi_confirm: '1'
ec_funded: 1
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- _id: 0aa60e99-070f-11eb-9043-a6de6bdc3afa
call_identifier: H2020
grant_number: '949120'
name: 'Tribocharge: a multi-scale approach to an enduring problem in physics'
publication_identifier:
isbn:
- 978-3-99078-083-1
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
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- id: '20481'
relation: part_of_dissertation
status: public
- id: '12109'
relation: part_of_dissertation
status: public
- id: '19278'
relation: part_of_dissertation
status: public
- id: '17373'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Scott R
full_name: Waitukaitis, Scott R
id: 3A1FFC16-F248-11E8-B48F-1D18A9856A87
last_name: Waitukaitis
orcid: 0000-0002-2299-3176
title: Experimental probing of nanoscale charge features and surface morphology changes
during tribocharging
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...
---
OA_place: publisher
_id: '20203'
abstract:
- lang: eng
text: Tribocharging, or contact electrification, is the phenomenon in which two
initially neutral materials exchange electric charge through contact and subsequent
separation. While it is widely observed in everyday life and crucial to numerous
natural processes, even the most basic aspects of tribocharging are still a mystery—what
are the charge carriers involved and what drives their exchange? This work spans
three separate projects that address different aspects of tribocharging. First,
we introduce a novel strategy combining Finite Element Method (FEM) simulations
with Kelvin Probe Force Microscopy (KPFM) to quantitatively extract surface charge
density from surface voltage maps. Second, we present a simple theoretical model
that allows for the existence of triboelectric cycles, under the assumption that
multiple charge carrying species are involved. Third, we present experimental
evidence that identical materials can spontaneously evolve into a triboelectric
series, driven by contact history. Modeling this behavior enables the replication
of experimental results with simulations, and even experimentally forcing the
appearance of a pre-designed series by manipulating contact history. Together,
the findings from these projects challenge traditional views on tribocharging,
provide new tools for probing it, and open up new avenues of research—all with
the hopes of bringing us closer to understanding this puzzling phenomenon.
acknowledged_ssus:
- _id: M-Shop
- _id: NanoFab
- _id: EM-Fac
- _id: LifeSc
- _id: ScienComp
acknowledgement: "The project in Chapter 2 has received funding from the European
Research Council (ERC) under\r\nthe European Union’s Horizon 2020 research and innovation
programme (Grant Agreement\r\nNo. 949120).\r\nThe project in Chapter 3 has received
funding from the European Research Council (ERC) under\r\nthe European Union’s Horizon
2020 research and innovation programme (Grant Agreement\r\nNo. 949120).\r\nThe project
in Chapter 4 has received financing from the European Research Council grant\r\nagreement
No. 949120 under the European Union’s Horizon 2020 research and innovation\r\nprogramme.
The Analytical Instrumentation Center of the TU Wien acknowledges support by\r\nthe
FFG project ‘ELSA’ under grant no. 884672. C.M.P. and M.O. acknowledge the state\r\nof
Lower Austria and the European Regional Development Fund under grant no. WST3-F542638/004-2021.\r\n"
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Juan Carlos A
full_name: Sobarzo Ponce, Juan Carlos A
id: 4B807D68-AE37-11E9-AC72-31CAE5697425
last_name: Sobarzo Ponce
citation:
ama: 'Sobarzo Ponce JCA. Tribocharging of identical insulators: Triboelectric series,
triboelectric cycles and surface charges. 2025. doi:10.15479/AT-ISTA-20203'
apa: 'Sobarzo Ponce, J. C. A. (2025). Tribocharging of identical insulators:
Triboelectric series, triboelectric cycles and surface charges. Institute
of Science and Technology Austria. https://doi.org/10.15479/AT-ISTA-20203'
chicago: 'Sobarzo Ponce, Juan Carlos A. “Tribocharging of Identical Insulators:
Triboelectric Series, Triboelectric Cycles and Surface Charges.” Institute of
Science and Technology Austria, 2025. https://doi.org/10.15479/AT-ISTA-20203.'
ieee: 'J. C. A. Sobarzo Ponce, “Tribocharging of identical insulators: Triboelectric
series, triboelectric cycles and surface charges,” Institute of Science and Technology
Austria, 2025.'
ista: 'Sobarzo Ponce JCA. 2025. Tribocharging of identical insulators: Triboelectric
series, triboelectric cycles and surface charges. Institute of Science and Technology
Austria.'
mla: 'Sobarzo Ponce, Juan Carlos A. Tribocharging of Identical Insulators: Triboelectric
Series, Triboelectric Cycles and Surface Charges. Institute of Science and
Technology Austria, 2025, doi:10.15479/AT-ISTA-20203.'
short: 'J.C.A. Sobarzo Ponce, Tribocharging of Identical Insulators: Triboelectric
Series, Triboelectric Cycles and Surface Charges, Institute of Science and Technology
Austria, 2025.'
corr_author: '1'
date_created: 2025-08-21T11:42:59Z
date_published: 2025-08-27T00:00:00Z
date_updated: 2026-07-29T13:11:25Z
day: '27'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: ScWa
doi: 10.15479/AT-ISTA-20203
doi_confirm: '1'
ec_funded: 1
file:
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creator: jsobarzo
date_created: 2025-08-27T14:50:32Z
date_updated: 2025-08-27T14:50:32Z
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date_created: 2025-08-27T14:50:32Z
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language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
page: '96'
project:
- _id: 0aa60e99-070f-11eb-9043-a6de6bdc3afa
call_identifier: H2020
grant_number: '949120'
name: 'Tribocharge: a multi-scale approach to an enduring problem in physics'
publication_identifier:
isbn:
- 978-3-99078-062-6
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '12109'
relation: part_of_dissertation
status: public
- id: '15322'
relation: part_of_dissertation
status: public
- id: '19278'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Scott R
full_name: Waitukaitis, Scott R
id: 3A1FFC16-F248-11E8-B48F-1D18A9856A87
last_name: Waitukaitis
orcid: 0000-0002-2299-3176
title: 'Tribocharging of identical insulators: Triboelectric series, triboelectric
cycles and surface charges'
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: dissertation
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
year: '2025'
...
---
OA_place: publisher
_id: '18588'
abstract:
- lang: eng
text: "This thesis is an experimental work about two distinct research projects
that evolved from a single project: non-equilibrium dynamics of an acoustically
vibrated particle and microfabrication of particles with nano-scale 3D printing.
The first project explores non equilibrium dynamics of a particle driven by ultrasonic
vibrations. We design an experimental system consisting of an electromechanical
vibration scheme to drive the particle’s vibrations and an imaging scheme to track
its trajectories. We study the trajectories to determine how the particle’s dynamics
evolve under the driven conditions, considering out of equilibrium systems in
the context of equilibrium statistical mechanics. Using a Langevin framework and
the Boltzmann factor, we characterize the particle’s dynamics as complex; the
particle motion\r\nis not purely diffusive. We extract physical parameters like
spring constant, effective temperature, damping coefficient and resonance frequency.\r\n\r\nIn
the second project, we explore and develop techniques in the design and microfabrication
of particles across scales. Microfabrication involves building structures at the
micron or submicron scale. These designed miniaturized patterns, objects, or devices
are useful in biophysics, pharmacology, medical biology, and nanotechnology. We
specifically apply two-photon polymerization, a form of 3D nano printing. We print
millimetric particles, characterizing different designs to evaluate and showcase
the resolution, aspect ratio integrity and print quality of the printing process.
We also design and fabricate a microsensor to deflect under applicable force of
order 0.1 pN. We present fundamental concepts needed to design the microsensor,
showcasing 3D printing at considerably smaller scales down to the µm or below."
acknowledged_ssus:
- _id: NanoFab
- _id: M-Shop
acknowledgement: "I would like to acknowledge Scott Waitukaitis and Jérémie Palacci,
for their supervision, and their extensive support of my learning. \r\n\r\nFor the
beautiful characterization images used in this work, I would like to thank Dr. Daniel
Grober, Samuel Hajek and Felix Pertl.\r\n\r\nThe Palacci group, particularly Malina
Strugaru and Dan Grober, for their continuous guidance in decoding and following
my streams of thought.\r\n\r\nTo the Waitukaitis group, for helping me find my footing
in science, and making me feel at\r\nhome.\r\n\r\nTo the Nanofabrication Facility
(NFF) at ISTA, for training me in significant aspects of my research. The MIBA Facility,
and particularly Todor Asenov for consistently picking up the phone for my machining
and designing needs.\r\n\r\nTo my friends, Mariana, Lenka, Aaron, Rebecca, Eavan
who provided an ear, wine, and a lot more when I needed to vent, talk through my
crises as well as experiment. For the walks, for the coffees, for reading through
my work and providing edits, for dinners to take me out of blocks and binds and
for cheering me on when it felt insurmountable. \r\n\r\nFinally, I am grateful to
Griff and Fletcher, whose music helped me through several blocks, especially with
my writing.\r\n\r\nMy science would not have been possible without the guidance,
support and contributions of\r\nall these people, and more."
alternative_title:
- ISTA Master's Thesis
article_processing_charge: No
author:
- first_name: Cecelia N
full_name: Mweka, Cecelia N
id: 2a69ab4b-896a-11ed-bdf8-cb8641cf2b21
last_name: Mweka
citation:
ama: Mweka CN. Non equilibrium dynamics of driven individual particles and 3D printing
across scales. 2024. doi:10.15479/at:ista:18588
apa: Mweka, C. N. (2024). Non equilibrium dynamics of driven individual particles
and 3D printing across scales. Institute of Science and Technology Austria.
https://doi.org/10.15479/at:ista:18588
chicago: Mweka, Cecelia N. “Non Equilibrium Dynamics of Driven Individual Particles
and 3D Printing across Scales.” Institute of Science and Technology Austria, 2024.
https://doi.org/10.15479/at:ista:18588.
ieee: C. N. Mweka, “Non equilibrium dynamics of driven individual particles and
3D printing across scales,” Institute of Science and Technology Austria, 2024.
ista: Mweka CN. 2024. Non equilibrium dynamics of driven individual particles and
3D printing across scales. Institute of Science and Technology Austria.
mla: Mweka, Cecelia N. Non Equilibrium Dynamics of Driven Individual Particles
and 3D Printing across Scales. Institute of Science and Technology Austria,
2024, doi:10.15479/at:ista:18588.
short: C.N. Mweka, Non Equilibrium Dynamics of Driven Individual Particles and 3D
Printing across Scales, Institute of Science and Technology Austria, 2024.
corr_author: '1'
date_created: 2024-11-27T09:12:02Z
date_published: 2024-11-29T00:00:00Z
date_updated: 2026-04-07T12:42:13Z
day: '29'
ddc:
- '530'
degree_awarded: MS
department:
- _id: GradSch
doi: 10.15479/at:ista:18588
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oa: 1
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page: '61'
publication_identifier:
issn:
- 2791-4585
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Scott R
full_name: Waitukaitis, Scott R
id: 3A1FFC16-F248-11E8-B48F-1D18A9856A87
last_name: Waitukaitis
orcid: 0000-0002-2299-3176
- first_name: Jérémie A
full_name: Palacci, Jérémie A
id: 8fb92548-2b22-11eb-b7c1-a3f0d08d7c7d
last_name: Palacci
orcid: 0000-0002-7253-9465
title: Non equilibrium dynamics of driven individual particles and 3D printing across
scales
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2024'
...