High speed microfluidic prototyping by programmable proximity aperture MeV ion beam lithography

Microfluidics refers to the science and technology for controlling and manipulating fluids that flow along microchannels. For the development of complex prototypes, many microfluidic test structures are required first. Normally, these devices are fabricated via photolithography. This technique requires a photomask for transferring a pattern to photoresists by exposing with UV light. However, this method can be slow when a new structure is required to change. This is because a series of photomasks are needed, which is time consuming and costly. Here, we present a programmable proximity aperture lithography (PPAL) technique for the development of microfluidic prototype in poly(methyl methacrylate) or PMMA. This method is based on using a mask made up of two movable L-shaped apertures in close proximity to the target. The PPAL allows microfluidic chips that are designed with complex components having large and small (∼1 μm-∼500 μm) pattern elements to be fabricated rapidly. In this paper, the fabrication process with test examples of microfluidic circuit designs is presented. Experimental results show that new patterns can be changed and produced in a few hours demonstrating that the PPAL technique is a rapid method for development of microfluidic prototypes in PMMA.