Recent Advances in Multi‐Photon 3D Laser Printing: Active Materials and Applications

Abstract

Since the pioneering work of Kawata and colleagues in 1997, multi‐photon 3D laser printing, also known as direct laser writing, has made significant advancements in a wide range of fields. Moreover, the development and commercialization of photocurable inks for this technique have expanded rapidly. One of the current trends is the transition from static to active printable materials, often referred to as 4D microprinting, which enables a new degree of control in the printed systems. This review focuses on four primary application areas: microrobotics, optics and photonics, microfluidics, and life sciences, highlighting recent progress and the crucial role of active materials, including liquid crystalline elastomers, hydrogels, shape memory polymers, and composites, among others. It also addresses ongoing challenges and provides insights into the future prospects in the different fields.

Direct laser writing-enabled 3D printing strategies for microfluidic applications

“…It is important to note that researchers have demonstrated a vast array of photomaterials as well as photocomposites to be compatible with 2PP-based fabrication processes, as discussed in numerous recent review articles. [10][11][12][13][14] Briefly, to be compatible with DLW protocols, the components of the photomaterial-i.e., the photoinitiator(s), monomer(s), and/or oligomer(s)-must be transparent in the wavelength (λ) of the laser used for DLW, the monomer/ oligomer must be transparent in the two-photon absorption wavelength (λ/2), and the photoinitiator must: (i) absorb at the two-photon absorption wavelength, (ii) have a high cross section (i.e., more likely to transition to a higher state when sufficient energy is absorbed), and (iii) have a high quantum efficiency (i.e., probability the molecule will break down into active fragments). [14][15][16] Acrylate-based photoresists represent one of the most prominent classes of photomaterials for DLW with benefits including low costs, high availability, transparency at visible and near-infrared wavelengths, stability after polymerization, and ease of development.…”

“…It is important to note that researchers have demonstrated a vast array of photomaterials as well as photocomposites to be compatible with 2PP-based fabrication processes, as discussed in numerous recent review articles. 10–14 Briefly, to be compatible with DLW protocols, the components of the photomaterial— i.e. , the photoinitiator(s), monomer(s), and/or oligomer(s)—must be transparent in the wavelength ( λ ) of the laser used for DLW, the monomer/oligomer must be transparent in the two-photon absorption wavelength ( λ /2), and the photoinitiator must: (i) absorb at the two-photon absorption wavelength, (ii) have a high cross section ( i.e.…”

Fraxicon for Optical Applications with Aperture ∼1 mm: Characterisation Study

“…Fs laser-fabricated optical elements are useful for beam collimation [35], shaping, imaging [36], telecommunications [37], and sensing [38], with an expanding range of functionalities and applications due to the possibility of miniaturisation and efficient fabrication by direct laser writing [39]. The applications of 3D polymerisation were recently reviewed for micro-mechanical applications triggered by different stimuli: light, temperature, and pH [40]. The use of specialised (undisclosed composition) two-photon absorbing photo-resists, hydrogels, and glass composites developed for commercial 3D printers based on fast scanning and high-repetition-rate fs oscillators is a fast-growing application field [41], with a vision of 3D printing applications of computer-designed complex optical elements [42].…”