Roberto Bernasconi1 Federico Cuneo1 Elena Carrara1 Georgios Chatzipirpiridis2 Marcus Hoop2 Bradley Nelson2 Salvador Pané2 Caterina Credi1 Marinella Levi1 Luca Magagnin1

1, Politecnico di Milano, Milano, , Italy
2, ETH Zurich, Zurich, , Switzerland

The main trend in modern medicine, made possible by the recent advance in medical technology, is minimally invasive surgery. Traditional surgery typically requires incision of living tissues, which causes extensive local damage that requires time to heal. On the contrary, by using techniques that strongly limit tissue incision, complications can be considerably reduced. Many minimally invasive techniques are already in use [1], while more innovative ones are currently under development.

One of the most attractive approaches currently under investigation consists in the use of remotely controlled microrobots. These devices are able to perform a variety of tasks in vivo, including drug and cell delivery, microsurgery or diagnosis. By using microrobots, the operation is performed exclusively in the target zone, with minimal damage for the surroundings. To operate inside human body, microdevices must be moved wirelessly in the less invasive way possible but with high control over position and speed. Magnetic actuation has been proposed as optimal to achieve a controlled motion for microrobots [2].

An intriguing application for these magnetically controlled microrobots is cell delivery: cells are loaded on a microdevice, which brings them in the place inside human where they must exert their therapeutic action. Examples of such devices are available in literature [3] and present a classical scaffold structure, able to accommodate cells.

The aim of this work is the manufacturing of a magnetically controllable cylindrical scaffold potentially usable for cell delivery. Stereolithography is used to model microsized scaffolds, which are subsequently covered with functional layers. Electroless metallization, a costless and scalable approach, is used to deposit such layers. In particular, a semi-hard magnetic alloy is applied to allow magnetic actuation. A gold coating constitutes the final layer to impart biocompatibility to the surface of the microrobots. Magnetic control and human cell biocompatibility of obtained devices is investigated, as well as their microstructure.

The work presented was carried out in the framework of the interdepartmental laboratory MEMS&3D of Politecnico di Milano, Italy.

[1] C.T. Frantzides et al., Atlas of Minimally Invasive Surgery, Saunders (2008)
[2] F. Qiu et al., Engineering 1(1): 21-26 (2015)
[3] S. Kim et al., Adv. Mater. 25: 5863–5868 (2013)