Hybrid additive-subtractive femtosecond 3D manufacturing of nanofilter-based microfluidic separator

The femtosecond (fs) laser is a well-established tool in material processing. Due to highly nonlinear light-matter interaction in a time frame shorter than heat dissipation from the laser affected zone, fs pulses enable extremely precise "cold processing". Both additive and subtractive structuring can be realized. Here we demonstrate how medical device fabrication can benefit from 3D additive-subtractive fs processing. The produced functional element is a microfluidic macromolecule separator based on integrated nanofilters. The channel system is produced using direct laser ablation and is similar to cm in overall size with channels with 150-250 mu m cross section. The filters are integrated by 3D laser lithography. Pore sizes-250-1500 nm. Furthermore, various channel sealing solutions are considered, discussing their advantages and disadvantages. A selective multi-photon polymerization-based solution is chosen for channel sealing, finishing the microfluidic system. The overall throughput of the process is considered, showing that it is near-capable for mass production. We demonstrated that the capability of freely choosing between additive and subtractive structuring in one highly automated workstation simplifies the design and fabrication process.