Fiber‐Optic Photoacoustic Generator Realized by Inkjet‐Printing of CNT‐PDMS Composites on Fiber End Faces

Abstract

In recent years, photoacoustic generators based on multiwalled carbon nanotubes (MWCNT) and polydimethylsiloxane (PDMS) are manufactured in a variety of ways, which influences the properties of the generators with respect to frequency bandwidth, sound wave pressure, robustness, and reproducibility. Due to the high optical absorption of MWCNTs and the high thermal expansion coefficient of PDMS, this combination is ideally suited for use as a photoacoustic generator. This study presents a novel method to produce photoacoustic generators based on long‐term stable MWCNT and PDMS inks with a high reproducibility by means of inkjet‐printing. The MWCNT‐PDMS layers (thicknesses of 2–4 µm), printed directly onto the distal end face of a multimode glass fiber, show a good homogeneity and low optical transmission (19–21%). After the preparation of the fiber pieces, the inkjet printer performs all steps automatically in a time period of 30–60 s per layer. The generated ultrasonic pressure (0.39–0.54 MPa) and frequency bandwidth (1.5–12.7 MHz) can be measured at a distance of ≈4 mm with a laser fluency of 12.7 mJ cm−2. These highly reproducible printed photoacoustic generators can be well used for nondestructive material testing and medical applications.

Material jetting for advanced applications: A state-of-the-art review, gaps and future directions

“…The printed photoacoustic generators show a good homogeneity and low optical transmission (19 -21%). The generated ultrasonic pressure (0.39 -0.54 MPa) and frequency bandwidth (1.5 -12.7 MHz) can be measured at a distance of ≈ 4 mm with a laser fluence of 12.7 mJ cm -2 [262]. Fig.…”

Fully Inkjet-Printed Carbon Nanotube-PDMS-Based Strain Sensor: Temperature Response, Compressive and Tensile Bending Properties, and Fatigue Investigations

“…The synthesis of the inks used for inkjet printing in this work is based on recent research projects realising an inkjetprinted fibre-optic photoacoustic generator using MWCNTs in combination with PDMS [16], [17]. To facilitate the printing process and extend the shelf-life of the ink, a two-step printing process was chosen.…”

“…The second component (PDMS/CA) contains PDMS and the curing agent (CA) where an additional short chain PDMS acts as a solvent. The undissolved parts of the PDMS/CA ink are homogenized for 2 minutes using a 130 W ultrasonic homogenizer [17]. The additional PDMS in the first component assists the homogeneous distribution of CNTs within the PDMS matrix which reduces separation between CNT and PDMS and promotes stability and adhesion to the substrate of the printed structures.…”