Two in One: Light as a Tool for 3D Printing and Erasing at the Microscale

Abstract

The ability to selectively remove sections from 3D‐printed structures with high resolution remains a current challenge in 3D laser lithography. A novel photoresist is introduced to enable the additive fabrication of 3D microstructures at one wavelength and subsequent spatially controlled cleavage of the printed resist at another wavelength. The photoresist is composed of a difunctional acrylate cross‐linker containing a photolabile o‐nitrobenzyl ether moiety. 3D microstructures are written by photoinduced radical polymerization of acrylates using Ivocerin as photoinitiator upon exposure to 900 nm laser light. Subsequent scanning using a laser at 700 nm wavelength allows for the selective removal of the resist by photocleaving the o‐nitrobenzyl group. Both steps rely on two‐photon absorption. The fabricated and erased features are imaged using scanning electron microscopy (SEM) and laser scanning microscopy (LSM). In addition, a single wire bond is successfully eliminated from an array, proving the possibility of complete or partial removal of structures on demand.

It's in the Fine Print: Erasable Three‐Dimensional Laser‐Printed Micro‐ and Nanostructures

“…Some of us recently reported a breakthrough in designing a photo‐labile photoresist enabling additive fabrication of 3D microstructures using one wavelength and subsequent spatially controlled cleavage of the printed resist using another wavelength . The photoresist is composed of a bifunctional acrylate crosslinker containing a photo‐labile o ‐nitrobenzyl ether moiety.…”

Es ist im Kleingedruckten: Löschbare dreidimensionale lasergedruckte Mikro‐ und Nanostrukturen

“…Einige von uns berichteten kürzlich über einen Durchbruch bei der Entwicklung eines lichtlabilen Photolacks, der die additive Herstellung von 3D‐Mikrostrukturen mit einer Wellenlänge und die anschließende räumlich kontrollierte Spaltung des gedruckten Lacks mit einer anderen Wellenlänge ermöglicht . Der Photolack besteht aus einem difunktionellen Acrylatvernetzer, der eine lichtlabile o ‐Nitrobenzylethereinheit enthält.…”

Laser‐Triggered Writing and Biofunctionalization of Thiol‐Ene Networks

“…[ 11,12 ] In a very recent work, networks based on o ‐NBE chemistry were successfully employed for 3D print and then erase 3D structures by employing a two wavelengths two photon equipment. [ 15 ] In previous studies, we explored the possibility to introduce o ‐NBE moieties in a wide range of different networks such as epoxy and methacrylic ones as well as thiol‐ene, thiol‐epoxy and thiol‐yne polymer networks fabricated by click chemistry. [ 16–20 ] In this context, thiol‐ene networks containing o ‐NBE moieties were used as positive/negative tone photoresist with good resolution.…”

“…[ 22 ] Here we also evidence that the use of a laser source for activating the cleavage reaction is of particular interest since it allows not only high spatial control but also enables dry development (i.e., removal of cleaved molecules without the use of a solvent) while typically solvents are required to remove the soluble species formed in the exposed areas. [ 15–20,23,24 ]…”