Multiscale 3D-printing of a suspended hollow microfluidic device

Abstract

Suspended hollow micro-cantilevers have been employed for zeptogram (10^-21 g) mass measurements, pipetting of femtoliter
(10^-15 L) volumes, and studies on mechanical interaction with single cells. The main fabrication method of these devices is by standard clean room micro/nano fabrication techniques, however, they are inherently planar, thus limiting three dimensional design, and the required masks make prototyping time-consuming and expensive. In this work maskless 3D-printing by two-photon polymerization (2PP) was used to fabricate hollow microfluidic cantilevers. A novel fluidic interfacing approach was developed by directly 2PP-printing the cantilever on a stereolithographic microfluidic device for handling and connecting to the external world. Several 350 µm long cantilevers with an aperture of 25 µm were mechanically characterised by laser Doppler vibrometry and the fundamental frequency was measured at 99,6 kHz, with a quality factor of approximately 174 in air. A hydraulic model was constructed and fluidic functionality was demonstrated. The non-optimised printing time of the full device was approximately 2.5 hours, performed by only two automated maskless fabrication steps. This printing method enables rapid prototyping of ready-to-use suspended microfluidic devices.