Femtosecond Direct Writing of PDMS Channels and Its Application in Tissue Engineering

Application in Tissue Engineering

Nannette Hernandez¹, Sabrina McCarthy¹, Alessandro Enrico² , Anna Herland³ ,

Frank Niklaus² and Göran Stemme²

¹ Department of Chemical Engineering, The City College of New York, CUNY, New York, NY 10031, USA

² Department of Micro and Nanosystems, School of Electrical Engineering, Royal Institute of Technology, Stockholm, Sweden

³ Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden

Fabrication of channels in elastomers such as PDMS is crucial for microfluidics and tissue engineering. Conventional approaches for patterning PDMS exploit moulding and subsequent crosslinking. Two conventional approaches are 1) 3D moulding which require special or multistep demoulding procedures and 2) multi layered design moulding where PDMS is patterned and then bonded to another flat or patterned layer of material such as PDMS or glass. However, the former approach results in limited 2D geometric patterns while the latter requires a mould to cast the PDMS as well as demoulding which may be time and resource expensive. Here we propose femtosecond laser direct writing of channels in PDMS. It is possible to ablate anywhere in the depth of a PDMS block by adjusting the location of the focal point in the material.

A 1040nm femtosecond laser was used for direct writing of channel-like microstructures in a block of 1:10 PDMS. Parameters such as repetition rate and power were optimized to achieve these channel-like microstructures. For this purpose, it was observed that multiple laser passes in the same position facilitates the removal of the ablation debris inside the channel. Moreover, it was observed that the diameter of channels decreased with increasing processing depth in the material. In light of these results, femtosecond laser direct writing results in a simple, precise fabrication process in PDMS with minimal post processing and without need for moulding and demoulding.