Rapid prototyping of microstructures in polydimethylsiloxane (PDMS) by direct UV-lithography

Abstract

Microstructuring of polydimethylsiloxane (PDMS) is a key step for many lab-on-a-chip (LOC) applications. In general, the structure is generated by casting the liquid prepolymer against a master. The production of the master in turn calls for special equipment and know how. Furthermore, a given master only allows the reproduction of the defined structure. We report on a simple, cheap and practical method to produce microstructures in already cured PDMS by direct UV-lithography followed by chemical development. Due to the available options during the lithographic process like multiple exposures, the method offers a high design flexibility granting easy access to complex and stepped structures. Furthermore, no master is needed and the use of pre-cured PDMS allows processing at ambient (light) conditions. Features down to approximately 5 µm and a depth of 10 µm can be realised. As a proof of principle, we demonstrate the feasibility of the process by applying the structures to various established soft lithography techniques.

Silicones for Microfluidic Systems

“…• Direct UV lithography (no master), followed by chemical development [94] or reactive ion etching [95]. • Low-energy metal ion implantation (buckling of PDMS surface to produce organized 3D surface features) [96] and structured metal fi lms (formation of wavy corrugations of order dependent on the sputtered metal) [97].…”

Position-resolved Surface Characterization and Nanofabrication Using an OpticalMicroscopeCombined with a Nanopipette/Quartz Tuning Fork Atomic Force Microscope

“…Moreover, the straight alignment of a ∼20 nm single Si nanowires was achieved and aligned on the desired spot using the ∼100 nm nanopipette. PDMS is a versatile material useful in the field of biosystems, such as for soft matter and lab-on-a-chip (LOC) applications [35][36][37], where microscale patterns are generally fabricated by photolithography or imprinting [38]. In this work, we demonstrate the direct patterning of PDMS, which is mixed in a 1:10 ratio with a curing agent and base (Dow Corning, Sylgard 184 elastromer kit) using the proposed liquid delivery system.…”

Fabrication of Microstructures Embedding Controllable Particles inside Dielectrophoretic Microfluidic Devices

“…DEP force should be generated inside the solution which means the microfluidic channel is also needed. Microfluidic devices made of PDMS are key components in many microfluidic applications [28]. The mould of the microfluidic channel was made with photoresist SU-8 (MicroChem Corp.).…”