Direct Laser Writing of Ferromagnetic Nickel Utilizing the Principle of Sensitized Triplet-Triplet Annihilation Upconversion

TL;DR

This paper introduces a novel photoresist enabling direct laser writing of ferromagnetic nickel structures using a sensitized triplet-triplet annihilation upconversion process, advancing 3D fabrication for sensing and data storage.

Contribution

It presents a new photoresist method that allows reliable laser writing of ferromagnetic nickel under ambient conditions, a significant breakthrough in metallic 3D microfabrication.

Findings

Successful fabrication of ferromagnetic nickel microstructures

Confirmation of ferromagnetic properties via magnetic measurements

Demonstration of spatially confined nickel deposition

Abstract

Direct laser writing of ferromagnetic microstructures is of great interest for sensing and data storage in compact three-dimensional architectures. However, reliable direct laser writing of metallic and even more so ferromagnetic materials remains a major challenge. Here, we present a novel photoresist suitable to direct laser write ferromagnetic nickel based on sensitized triplet-triplet annihilation upconversion. By combining an in-situ photochemical deoxygenation process with a sensitized triplet-triplet annihilation upconversion process as well as a photoreduction of Ni2+ ions, the deposition of metallic nickel is enabled under ambient conditions. Using this approach, nickel structures are fabricated as a proof of concept. Scanning electron microscopy and EDX analysis confirm the spatially confined deposition of nickel, while magnetic characterization by vibrating sample magnetometry and scanning NV magnetometry demonstrate the ferromagnetic nature of the printed structures. This work presents a major step forward in extending the possibilities of direct laser writing to metallic and ferromagnetic materials.