Photoacoustic signal enhancements were observed with a pair of time-delayed femtosecond pulses upon excitation of gold nanosphere colloidal suspension. A systematic experimental investigation of photoacoustic intensity within the delay time, Δt = 0 to 15 ns, was carried out. The results revealed a significant enhancement factor of ∼2 when the pre-pulse energy is 20-30% of the total energy. Pre-pulse and main pulse energy ratios, Ep(1):Es(2), were varied to determine the optimal ratio that yields to maximum photoacoustic signal enhancement. This enhancement was ascribed to the initial stage of thermalization and bubble generation in the nanosecond time scale. Pre-pulse scattering intensity measurements and numerical finite-difference time-domain calculations were performed to reveal dynamics and light field enchancement, respectively.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/OE.25.019497 | DOI Listing |
Microsurgery
January 2025
Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Thinning of anterolateral thigh flap is challenging. Anatomical studies have shown variations in arterial branching patterns in the subcutaneous layer, which were suspected to be the reason for the high frequency of thinning failures. We attempted to visualize subcutaneous arterial courses preoperatively and perform thinning of perforator flaps using this information appropriately.
View Article and Find Full Text PDFAnal Chem
January 2025
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, Liaoning, China.
A cantilever-enhanced fiber-optic photoacoustic (PA) spectrophone is reported for trace gas detection at a low-pressure environment. A cantilever-based fiber-optic Fabry-Perot (F-P) interferometer (FPI) is utilized for simultaneous measurement of air pressure and PA pressure. Since the cantilever resonance frequency follows air pressure linearly, the fundamental frequency intensity modulation (1-IM) technique is applied to scan the frequency response of the solid PA signal from tube wall absorption for tracking the cantilever resonance frequency in real time.
View Article and Find Full Text PDFSci Rep
December 2024
Center for Photonic Science and Engineering, Skolkovo Institute of Science and Technology, 30 Bolshoy Boulevard, bld. 1, Moscow, 121205, Russia.
Photonic-based methods are crucial in biology and medicine due to their non-invasive nature, allowing remote measurements without affecting biological specimens. The study of diatoms using advanced photonic methods remains a relatively underexplored area, presenting significant opportunities for pioneering discoveries. This research provides a comprehensive analysis of marine diatoms, specifically Nitzschia sp.
View Article and Find Full Text PDFNat Commun
December 2024
Institute for Biomedical Engineering and Institute of Pharmacology and Toxicology, Faculty of Medicine, University of Zurich, Zurich, Switzerland.
Resting-state functional connectivity (rsFC) has been essential to elucidate the intricacy of brain organization, further revealing clinical biomarkers of neurological disorders. Although functional magnetic resonance imaging (fMRI) remains a cornerstone in the field of rsFC recordings, its interpretation is often hindered by the convoluted physiological origin of the blood-oxygen-level-dependent (BOLD) contrast affected by multiple factors. Here, we capitalize on the unique concurrent multiparametric hemodynamic recordings of a hybrid magnetic resonance optoacoustic tomography platform to comprehensively characterize rsFC in female mice.
View Article and Find Full Text PDFPhotoacoustics
February 2025
College of Control Science & Engineering, China University of Petroleum (East China), Qingdao 266580, PR China.
Traditional beat frequency quartz-enhanced photoacoustic spectroscopy (BF-QEPAS) are limited by short energy accumulation times and the necessity of a decay period, leading to weaker signals and longer measurement cycles. Herein, we present a novel optomechanical energy-enhanced (OEE-) BF-QEPAS technique for fast and sensitive gas sensing. Our approach employs periodic pulse-width modulation (PWM) of the laser signal with an optimized duty cycle, maintaining the quartz tuning fork's (QTF) output at a stable steady-state level by applying stimulus signals at each half-period and allowing free vibration in alternate half-periods to minimize energy dissipation.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!