Scanning Probe Microscopy

Probe Based Lithography
Probe based lithography involves creating nanometer sized features from photoresist and metal on conducting and semiconducting substrates. Near field optical, electrical and thermal fields are employed in combination with evaporation, etching and electroplating to provide high-speed alternatives for mask-less nanofabrication.

Nanopositioning
A nanopositioner is a electromechanical device for moving objects in three dimensions with atomic, or sub-atomic resolution. Nanopositioners are employed in applications such as imaging, fabrication and optics. This field encompasses mechanical design, sensor design, and control theory. More details.

Electroactive Optics
Piezoelectric actuators can be combined with mirrors, lenses and objectives to actively control the path and properties of an optical field or laser beam. High speed electro-optics are required for precision lasers, maskless lithography, and microscopy.

Precision Sensors
This project aims to study the fundamental limitations of capacitive, optical and magnetic position sensors. New techniques are under development to provide sub-atomic resolution over extremely wide bandwidth.

Biomedical Devices
An endoscopic pill robot is being developed for noninvasive imaging and intervention. The robot can be swallowed and includes power transmission, 6-Dimensional localization, and locomotion.

Piezo Actuators and Amplifiers

Piezo bender actuator with integrated 200V power electronics
Piezo Robotics
Due to their compact size and high efficiency, piezoelectric actuators are ideal for micro-actuation in bio-inspired robotics. This project is developing actuators and mechanics for a piezoelectric dragon-fly robot.

Mai, N. L.; Hoang, T. A.; Vu, T. H.; Vu, H. D.; Doan, C.; Yong, Y. K.; Dinh, T. X.; Dao, D. V.; Dau, V. T.
Pulsated in-Situ Dried Electrostretching Fabrication of Microneedles for Transdermal Drug Delivery Proceedings
23rd International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers), 2025.
@proceedings{Mai2025c,
title = {Pulsated in-Situ Dried Electrostretching Fabrication of Microneedles for Transdermal Drug Delivery},
author = {N. L. Mai and T. A. Hoang and T. H. Vu and H. D. Vu and C. Doan and Y. K. Yong and T. X. Dinh and D. V. Dao and V. T. Dau},
doi = {10.1109/Transducers61432.2025.11110014},
year = {2025},
date = {2025-06-29},
abstract = {This paper reports a pioneering technique to fabricate microneedles (MNs) for transdermal drug delivery utilizing pulsated in-situ dried electrostretching (PIDES). This approach applies pulsed voltage to generate electrohydrodynamic forces that stretch and solidify a polymer droplet into a conical shape with a micrometer-scale tip. As the solvent evaporates, the polymer droplet is stretched in-situ into a cone and hardens, forming a sharp MN ideal for transdermal drug delivery. Penetration and mechanical tests confirm that the MNS have the necessary sharpness and strength for effective skin penetration. Furthermore, curcumin loading and a release test show that the MNS can effectively carry drugs and provide a gradual release of drug. These results demonstrate that PIDES is a promising, cost-effective, and straightforward method for developing efficient and painless transdermal drug delivery systems.},
howpublished = {23rd International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers)},
keywords = {},
pubstate = {published},
tppubtype = {proceedings}
}

Mai, N. L.; Yong, Y. K.; Hoang, T. A.; Vu, T. H.; Vu, H; Doan, V. C.; Cai, D.; Dinh, T. X.; Dao, D. V.; Dau, V. T.
Fabrication of Microneedles by Pulsating In Situ Dried Electrostretching for Transdermal Drug Delivery Journal Article
In: Small Methods, vol. 9, pp. 2500183, 2025, (The paper's cover art has been selected as the frontispiece of the journal, Oct 2025).
@article{Mai2025,
title = {Fabrication of Microneedles by Pulsating In Situ Dried Electrostretching for Transdermal Drug Delivery},
author = {N. L. Mai and Y. K. Yong and T. A. Hoang and T. H. Vu and H Vu and V. C. Doan and D. Cai and T. X. Dinh and D. V. Dao and V. T. Dau},
doi = {https://doi.org/10.1002/smtd.202500183},
year = {2025},
date = {2025-06-11},
urldate = {2025-06-11},
journal = {Small Methods},
volume = {9},
pages = {2500183},
abstract = {This paper introduces a novel pulsating in situ dried electrostretching (PIDES) technique for the fabrication of microneedles (MNs) for transdermal drug delivery. This method utilizes pulsed voltage to induce electrohydrodynamic forces that stretch and freeze a polymer droplet into a conical shape with a micrometer-scale tip. With the effects of solvent evaporation, the polymeric droplet is in situ stretched into a conical shape and solidified, transforming into a sharp MN, suitable for transdermal drug administration. Penetration and mechanical tests confirm that the MNs possess sufficient sharpness and strength for effective skin penetration applications. Additionally, curcumin loading and in vitro release tests with different concentrations demonstrate the MNs' ability to carry drugs and exhibit effective controlled release profiles. These findings highlight PIDES as a promising, low-cost, and simple approach for the development of painless and efficient transdermal drug delivery systems.},
note = {The paper's cover art has been selected as the frontispiece of the journal, Oct 2025},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

T. H. Vu N. L. Mai, H. Vu
Evaporation in electrohydrodynamic atomisation: A numerical and experimental investigation Journal Article
In: International Communications in Heat and Mass Transfer, vol. 165, Part B, pp. 109079, 2025.
@article{Mai2025b,
title = {Evaporation in electrohydrodynamic atomisation: A numerical and experimental investigation},
author = {N. L. Mai, T. H. Vu, H. Vu, C. Doan, Y. K. Yong, T. X. Dinh, D. V. Dao, V. T. Dau},
doi = {https://doi.org/10.1016/j.icheatmasstransfer.2025.109079},
year = {2025},
date = {2025-06-01},
urldate = {2025-06-01},
journal = {International Communications in Heat and Mass Transfer},
volume = {165, Part B},
pages = {109079},
abstract = {In this paper, the influence of evaporation in electrohydrodynamic atomization (electrospray) is numerically and experimentally investigated. The simulation was performed utilizing the Taylor-Melcher's leaky-dielectric model and the d2 Law to simulate thermophysical processes in electrospray. Experiments were conducted to validate the numerical approach and to investigate the influence of evaporation on particle morphology. Results by simulations are consistent with experiments, showing agreement in both Taylor-cone captured by high-speed camera and vapour field visualized by Schlieren imaging. Experiments on different solvents suggest major impacts of interelectrode distance on the residual solvent on the collected particles. However, these impacts were less significant on particle size and morphology particularly when using solvents with medium to low volatility. Particle size is found to increase with temperature and solvent volatility, confirming the correlation reported in literature. Moreover, evaporation was determined to have limited effect on the overall shape of the Taylor-cone and spray jet, due to inherently high vapour concentration around the nozzle vicinity. These contributions will improve the understanding of evaporation process in electrospray and offer useful guidelines for optimizing the technique, particularly in situations where evaporation is a key factor controlling particle size and minimizing harmful residue.
Keywords: Numerical methods; Evaporation; Electrospray; Electrohydrodynamic atomization; Experiments; Particle morphology
},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Keywords: Numerical methods; Evaporation; Electrospray; Electrohydrodynamic atomization; Experiments; Particle morphology

Ruppert, M. G.; Routley, B. S.; McCourt, L. R.; Yong, Y. K.; Fleming, A. J.
Modulated-Illumination Intermittent-Contact Tip-Enhanced Raman Spectroscopy Journal Article
In: ACS Nano Letters, vol. 25, iss. 14, pp. 5656-5662, 2025, ISSN: 1530-6984.
@article{Ruppert2025,
title = {Modulated-Illumination Intermittent-Contact Tip-Enhanced Raman Spectroscopy},
author = {M. G. Ruppert and B. S. Routley and L. R. McCourt and Y. K. Yong and A. J. Fleming},
url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2025/05/Article.pdf},
doi = {https://doi.org/10.1021/acs.nanolett.4c06397},
issn = {1530-6984},
year = {2025},
date = {2025-03-13},
urldate = {2025-03-13},
journal = {ACS Nano Letters},
volume = {25},
issue = {14},
pages = {5656-5662},
abstract = {This article presents a proof-of-concept for a new imaging method that combines tip-enhanced Raman spectroscopy with intermittent-contact atomic force microscopy to provide simultaneous nanometer-scale mechanical imaging with chemical contrast. The foremost difference from a standard tip-enhanced Raman microscope is the Raman illumination, which is modulated by the cantilever drive signal so that illumination is only active when the tip is close to the surface. This approach significantly reduces contact forces and thermal damage due to constant illumination while simultaneously reducing background Raman signals. Near-field optical and dynamic cantilever simulations highlight the effect of the imaging parameters on the tip–sample force and the evanescent field enhancement. The experimental images obtained with this new imaging method demonstrate a lateral resolution sufficient to identify single-walled carbon nanotube bundles with a full width at half-maximum of 20 nm.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Carlon, C. J.; Yong, Y. K.; Fleming, A. J.
Feasibility of Nano-Acoustic Subsurface Imaging for Atomic Force Microscopy Proceedings Article
In: IEEE International Conference on Mechatronics , Wollongong, Australia, 2025, ISBN: 979-8-3315-3389-2.
@inproceedings{C25b,
title = {Feasibility of Nano-Acoustic Subsurface Imaging for Atomic Force Microscopy},
author = {C. J. Carlon and Y. K. Yong and A. J. Fleming},
url = {https://www.precisionmechatronicslab.com/wp-content/uploads/2025/11/Feasibility_of_Nano-Acoustic_Subsurface_Imaging_for_Atomic_Force_Microscopy.pdf},
doi = {10.1109/ICM62621.2025.10934819},
isbn = {979-8-3315-3389-2},
year = {2025},
date = {2025-02-28},
urldate = {2025-02-28},
booktitle = {IEEE International Conference on Mechatronics },
address = {Wollongong, Australia},
abstract = {The feasibility of a new imaging regime for sub-surface Atomic Force Microscopy (AFM) is investigated using synthetic aperture focusing technique. This technique uses two Atomic Force Microscopy (AFM) probes to emit acoustic pulses and sense echoes. Unlike other existing subsurface AFM methods, Nano-Acoustic Subsurface AFM (NASAFM) provides cross-sectional images of a sample below the surface with depth information in the nanometre scale. In order to determine the best resolution, two ideal wideband AFM probes are considered in simulation. The results show that a 20 ps pulse with a bandwidth of 330 GHz was able to resolve two 50 nm discs, 500 nm below the surface, separated by 340 nm. Future work is needed to understand the relation between resolution and bandwidth, the optimal imaging parameters, and the sensing technique.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
