Stop Flow Interference Lithography

Applications

Polymeric structures with repeating 2-dimensional (2D) and 3D motifs at the micron scale and below have a variety of uses. Patterned 2D structures have been shown to have myriad applications in biosensors, tissue engineering, and diagnostic assay systems. The availability of more sophisticated 3D structures would enable important advances in photonics, information storage, and tissue engineering.

Problem Addressed

Many techniques have been developed to fabricate complex 3D structures at the micron scale and below using either top-down or bottom-up approaches. Bottom-up approaches like polymer phase separation, molecular self-assembly, or colloidal assembly are cheap and can cover large areas but face problems of defects and limitations in the type and the geometry of structures that can be formed. While top-down methods offer precise size and shape control, the need to construct the 3D structures using either a point-by-point or layer-by-layer process makes such methods as gray-scale photolithography, direct 3D writing, or 2-photon lithography very time consuming.

Technology

Stop flow interference lithography system for high throughput synthesis of 3-dimensionally patterned polymer particles. The system includes a microfluidic channel containing a stationary oligomer film and a phase mask located adjacent to the microfluidic channel. A source of collimated light is provided for passing the collimated light through the phase mask and into the microfluidic channel for interaction with the oligomer. The passage of the collimated light through the phase mask generates a 3-dimensional distribution of light intensity to induce crosslinking of the oligomer in high intensity regions thereby forming 3-dimensional structures.

Advantages

  • Interference Lithography (IL) enables one to rationally design complex and defect-free 1D, 2D and 3D patterns over large areas
  • IL also affords control over geometrical parameters, such as symmetry and volume fractions, of the structures formed
  • IL performed using an elastomeric PDMS phase mask provides simple and inexpensive processing, since only a single collimated beam is needed to form 3D interference patterns