A5068136202- Photoacoustic and Ultrasonic Imaging
- Optical Imaging and Spectroscopy Techniques
- Laser Applications in Dentistry and Medicine
- Ocular and Laser Science Research
- Laser Material Processing Techniques
- Vocational Education and Training
- Ultrasound Imaging and Elastography
- Thermography and Photoacoustic Techniques
- Optical Coherence Tomography Applications
- Sociology and Education Studies
- Laser Design and Applications
- Nanoplatforms for cancer theranostics
- Laser-Ablation Synthesis of Nanoparticles
- Education Methods and Technologies
- Innovation, Technology, and Society
- Optical Polarization and Ellipsometry
- Flexible and Reconfigurable Manufacturing Systems
- Digital Innovation in Industries
- Retinal and Macular Surgery
- Non-Invasive Vital Sign Monitoring
- Ultrasound and Cavitation Phenomena
- Geology and Paleoclimatology Research
- Retinal Development and Disorders
- Solid State Laser Technologies
- Economic and Social Issues
University of Bern
2015-2024
RWTH Aachen University
2012-2022
University Hospital of Bern
2011-2022
Leibniz Institute of Photonic Technology
2022
Friedrich Schiller University Jena
2022
John Wiley & Sons (Germany)
2022
Technical University of Denmark
2022
Munster Technological University
2022
National Yang Ming Chiao Tung University
2022
University of St Andrews
2022
In optoacoustic imaging, short laser pulses irradiate highly scattering human tissue and adiabatically heat embedded absorbing structures, such as blood vessels, to generate ultrasound transients by means of the thermoelastic effect. We present an vascular imaging system that records these on skin surface with transducer array displays images online. With a single pulse complete B-mode image can be acquired. The exploits high intrinsic optical contrast provides high-contrast without need for...
In medical imaging different techniques have been developed to gain information from inside a tissue. Optoacoustics is method generate tomography pictures of tissue using Q-switched laser pulses. Due thermal and pressure confinement, short light pulse generates distribution tissue, which mirrors absorbing structures can be measured outside the Using temporal back-projection method, on surface allows us picture This study presents novel computational algorithm, which, at least in principle,...
Plants exhibit life-long organogenic and histogenic activity in a specialised organ, the shoot apical meristem. Leaves flowers are formed within ring-shaped peripheral zone, which surrounds central site of stem cells. We have undertaken series high-precision laser ablation microsurgical tissue removal experiments to test functions different parts tomato meristem, reveal their interactions. Ablation zone led ectopic expression WUSCHELgene at periphery, followed by establishment new meristem...
Computed ultrasound tomography in echo mode (CUTE) allows determining the spatial distribution of speed-of-sound (SoS) inside tissue using handheld pulse-echo (US). This technique is based on measuring changing phase beamformed echoes obtained under varying transmit (Tx) and/or receive (Rx) steering angles. The SoS reconstructed by inverting a forward model describing how related to shift. Thanks straight-ray approximation, this linear and can be inverted real-time when implemented...
One concern during laser ablation of tissue is the mechanical injury that may be induced in vicinity site. This primarily due to rapid bubble expansion and collapse or laser-induced pressure waves. In this study, effect pulse duration on thermodynamics formation accompanying acoustic wave generation has been investigated.Q-switched holmium:YAG pulses (pulse 500 ns, energy 14 mJ) free-running 100-1,100 microseconds, 200 were delivered water phantoms via a 200- 400-microns fiber, respectively....
Leaves are arranged according to regular patterns, a phenomenon referred as phyllotaxis. Important determinants of phyllotaxis the divergence angle between successive leaves, and size leaves relative shoot axis. Young leaf primordia thought provide positional information meristem, thereby influencing positioning new hence angle. On contrary, meristem signals establish their dorsoventral polarity, which is prerequisite for formation blade. These concepts originate from classical microsurgical...
Abstract The damage adjacent to incisions created in dorsal mouse skin by overlapping Er 3+ and CO 2 laser pulses of a duration 250 μs is investigated histologically. It compared injuries induced long‐term heating. We demonstrate how the lateral thermal near cuts can be explained heat conduction. show that it necessary introduce as reservoir layer tissue has been liquefied during cutting process. width thermally damaged region depends mainly on extension liquid material remains cut after...
Widespread applications of ZnO nanoparticles (NP) in sun-blocking cosmetic products have raised safety concerns related to their potential transdermal penetration and resultant cytotoxicity. Nonlinear optical microscopy provides means for high-contrast imaging NPs lending vitro vivo assessment the nanoparticle uptake skin, provided nonlinear properties are characterized. We report on this characterization using NP commercial product, Zinclear, mean-sized 21 nm. Two-photon action...
A novel Fourier transform based reconstruction algorithm for solving the inverse problem in optoacoustic imaging is presented, which improves efficiency and image quality. algorithms make use of an interpolation law when signal components are mapped to source components. To overcome inadequacies affiliated with methods such as nearest neighbour, linear, cubic or spline interpolation, together data zero padding, we present a regularized method on forward model explicitly formulated compactly...
Background: Experimental tissue fusion benefits from the selective heating of superparamagnetic iron oxide nanoparticles (SPIONs) under high frequency irradiation. However, metabolic pathways SPIONs for remain unknown. Hence, goal this in vivo study was to analyze distribution different organs by means magnetic resonance imaging (MRI) and histological analysis after a SPION-containing patch implantation. Methods: patches were implanted rats. Three animal groups studied histologically over...
Aberrations of the acoustic wave front, caused by spatial variations speed-of-sound, are a main limiting factor to diagnostic power medical ultrasound imaging. If not accounted for, aberrations result in low resolution and increased side lobe level, over all reducing contrast deep tissue Various techniques have been proposed for quantifying analysing arrival time coherent echoes from so-called guide stars or beacons. In situations where star is missing, aperture-based may give ambiguous...
Water keeps puzzling scientists because of its numerous properties which behave oppositely to usual liquids: for instance, water expands upon cooling, and liquid is denser than ice. To explain this anomalous behaviour, several theories have been proposed, with different predictions the supercooled (liquid at conditions where ice more stable). However, discriminating between those experiments has remained elusive spontaneous nucleation. Here we measure sound velocity in stretched negative...
A novel three-dimensional (3-D) computational algorithm to reconstruct 3-D optoacoustic images from two-dimensional (2-D) pressure distributions generated at the sample surface is presented. The 2-D were measured as different delay times after excitation laser pulse. captured with a gated CCD camera local induces intensity changes of reflected probe beam irradiated sample. illumination time was 10 ns and resolution image 20 /spl mu/m. reconstruction based on decomposition into plane waves....
We investigated vapor bubbles generated upon irradiation of gold nanoparticles with nanosecond laser pulses. Bubble formation was studied both optical and acoustic means on supported single in suspension. Formation thresholds determined at different wavelengths indicate a bubble efficiency increasing the wavelength. Vapor generation Bac-1 cells containing accumulations same particles also wavelengths. Similarly, they showed an cell damage for longer by pulses were about half size when...
A new contrast agent for combined photoacoustic and ultrasound imaging is presented. It has a liquid perfluorocarbon (PFC) core of about 250 nm diameter coated by 30 thin polypyrrole (PPy) doped polymer shell emulsion that represents broadband absorber covering the visible near-infrared ranges (peak optical extinction at 1050 nm). When exposed to sufficiently high intensity or acoustic pulse, droplets vaporize form microbubbles providing strong increase in sensitivity specificity. The...
Reflection artifacts caused by acoustic inhomogeneities are a critical problem in epi-mode biomedical photoacoustic imaging. High light fluence beneath the probe results transients, which propagate into tissue and reflect back from echogenic structures. These reflection cause problems image interpretation significantly impact contrast imaging depth. We recently proposed method called PAFUSion (Photoacoustic-guided focused ultrasound) to identify such In its initial version, mimics...
Erbium and holmium lasers are attractive for minimally invasive surgical applications as they operate at wavelengths where tissues exhibit strong absorption due to their water content because these transmittable through optical fibers. In this study, the basic physical mechanisms underlying tissue ablation laser-induced effects using pulsed Er:YSGG (2.79 /spl mu/m) Ho:YAG (2.12 laser radiation presented compared, Q-switched (/spl tau/=40 ns, E/spl les/50 mJ) free-running tau/=250 400 mu/s)...
The shielding effectiveness of laser-induced breakdown from focused, visible laser pulses 5 ns to 125 fs is determined measurements transmission energy through the focal volume. efficiency decreases as a function pulse duration 300 and increases fs. results are compared with past studies at similar durations. support models may lead an optimization in ophthalmic surgery by reduction collateral effects.
Conversion of energy from a heat pulse to acoustic stress is theoretically and experimentally studied in detail. The was generated by laser radiation delivered via an optical fiber into absorbing liquid. experimental results indicate that tensile cavitation are induced front the tip at distance far below penetration depth radiation. occurrence near field submerged explained diffraction thermoelastic expansion wave. Good agreement between theoretical calculations based on three-dimensional...