UC Berkeley

Femtosecond laser-direct writing (FS-LDW) can functionalize the surface of diverse device components, including cell culture plates and medical implants. Since FS-LDW is in essence a non-contact fabrication method, it allows the surface patterning and micro-/nano-machining of material with minimal mechanical/thermal deformation. Hence, micro-/nanofabrication and material processing by femtosecond laser has attracted intense interest.

Ultrafast laser ablation using far-field optics in a tight focusing configuration offers substantial advantages for the direct, maskless and arbitrary patterning of various materials and curved surfaces, while maintaining high feature resolution. Patterned surfaces with nanoscale craters or ablated pattern on electrospinning fibrous scaffolds can control and direct the cell migration. Control of topographical features in the cellular microenvironment can be achieved by combining FS-LDW with new materials. Direct laser writing by multi-photon polymerization is a nonlinear optical technique that allows the fabrication of 3D structures with resolution beyond the diffraction limit (~100nm). Incorporation of self-assembled block-copolymer nanomaterials into such structure fabricated by two-photon polymerization and, produced mesoscale structures endowed with guided nanoscale patterns (~10nm). This new capability can be used in many applications, including advanced optical metamaterials as well as for efficient photovoltaic energy conversion. In contrast, using low numerical aperture objective lens, fast fibrous structure (high aspect ratio) fabrication is possible. Well-organized fibrous structure can be used for patient-/disease-specific drug testing platform.

Femtosecond laser direct writing is promising technique that can induce surface (e.g., via ablation) or volumetric patterning in a serial fashion (multi-photon polymerization). We applied these techniques to design and control multi-functional platform fabrication. As a result, FS-LDW fabricated structures exhibit higher resolution fabrication, and efficient functionality (e.g., in controlling the migration on 2D and 3D structure / tuning of mechanical stiffness of structure / directed self-assembly of block copolymer / enhancement of fluidic mixing.