Nano and microfabrication are general terms to indicate a broad selection of techniques suitable to produce functional structures at the nano or microscale. This ability is at the base of many advanced applications in the main fields of engineering. However, many techniques typically used in microfabrication, like lithography or thin film deposition, are characterized by a limited tridimensionality of the final product. These manufacturing methods are commonly said to operate in 2.5 dimensions, due to the limited envelope achievable in the vertical direction.

To overcome said limitations, 3D printing techniques able to work at the microscale have been introduced in the last few years. The application of such techniques, based on direct writing of the different layers that compose the object by mean of a laser beam, to microfabrication gave origin to a new concept of production: additive microfabrication [1]. The main disadvantage of methodologies like stereolithography (SLA) or two photons lithography (2PL) is the material used for printing: a mixture of photocurable polymers. The need to use resins implies significant limitations on the final properties of the object: relatively low mechanical properties and total or partial lack of conductivity. A possible approach to impart metallic properties to SLA or 2PL printed parts is the deposition of metal thin films on the surface of the 3D printed part.

In the present work, a possible hybrid production route that combines SLA and wet metallization is described in general and applied to real microfabrication. Electroless deposition on SLA resins has already been attempted in the past [2], as well as deposition of multilayers. Starting from these propaedeutic work, the hybrid SLA/wet metallization approach is here applied to the micromanufacturing of two prototypical devices belonging to two distinct classes: MEMS and magnetically steerable microdevices. These two selected applications demonstrate the applicability of the manufacturing methodology but does not limit the range of possible uses, which span from bioengineering to microelectronics or to microfluidics.

[1] Misawa, Hiroaki, ed. (2006). 3D Laser Microfabrication: Principles and Applications, Germany: Wiley

[2] R. Bernasconi, C. Credi, M. Tironi, M. Levi, L. Magagnin, Electroless Metallization of Stereolithographic Photocurable Resins for 3D Printing of Functional Microdevices. J. Electrochem. Soc. 164, B3059–B3066 (2017)