The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10−3 Pa/(W/m2), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.

A novel fiber-optic biosensor based on a localized surface plasmon coupled fluorescence (LSPCF) system is proposed and developed. This biosensor consists of a biomolecular complex in a sandwich format of . It is immobilized on the surface of an optical fiber where a complex forms the fluorescence probe and is produced by mixing Cy5-labeled antibody and protein A conjugated gold nanoparticles (Au-PA). The LSPCF is excited by localized surface plasmon on the GNP surface where the evanescent field is applied near the core surface of the optical fiber. At the same time, the fluorescence signal is detected by a photomultiplier tube located beside the unclad optical fiber with high collection efficiency. Experimentally, this novel LSPCF biosensor is able to detect mouse immunoglobulin G (IgG) at a minimum concentration of 1 pg/mL (7 fM) during the biomolecular interaction of the IgG with anti-mouse IgG. The analysis is expanded by a discussion of the amplification of the LSPCF intensity by GNP coupling, and overall, this LSPCF biosensor is confirmed experimentally as a biosensor with very high sensitivity.

The combination of intravascular ultrasound and intravascular photoacoustic imaging has been proposed for improving the diagnosis of arterial diseases. We describe a novel scan-head design for implementing such multimodality imaging. The proposed device has the potential to achieve a sufficiently small size for clinical intravascular applications. The design aims for efficient image data acquisition for facilitating real-time three-dimensional imaging and reducing the required laser pulse repetition frequency. The integrated scan head consists of a single-element, ring-shaped transducer for sideward ultrasound transmission, a multimode fiber with a cone-shaped mirror for optical illumination, and a single polymer microring with mechanical scanning. The phantom imaging and some experimental results are presented. A microring array can be realized in the future to achieve high-frame-rate intravascular multimodality imaging.

We propose a new scanhead design for combined ultrasound (US)/photoacoustic (PA) imaging that can be applied to dual-modality microscopy and biomedical imaging. Both imaging modalities employ the optical generation and detection of acoustic waves. The scanhead consists of an optical fiber with an axicon tip for excitation, and a microring for acoustic detection. No conventional piezoelectric device is needed, and the cost of the design makes it suitable for one-time, disposable use. Furthermore, a single laser pulse is employed to generate both US and PA signals. A subband imaging method can be applied to the receiver to enhance the contrast between the US and PA signals. Phantom data demonstrate the feasibility of this approach.