Si Substrate Si Substrate AZ-GXR(Positive PR)

Figure 1. A scheme of nanochannel fabrication with roof collapsed mask. PDMS mask has a nanoslit patterns with the height ranged from 350 to 700 nm and the widths from 40 μm to 80 μm. PDMS nanoslits are placed on the thin positive photoresis layer of thickness range from 100 nm to 1 μm. Then PDMS nanoslits spontaneously collapse. Conventional photolithography aligner transfer roof-collapsed nano-channel patterns to the photoresist layer. Here we present a radically simple approach for nanochannel fabrication without the use of any expensive equipment or any instrument modifications. Our approach consists of consecutive simple photolithographic steps: first, we prepare sub-micron high but very wide PDMS nanoslits by using soft lithography. Second, as a mask we utilize PDMS nanoslits collapsed on the thinly coated photoresist layer. Standard photolithography trans-fers roof-collapsed PDMS nanochannels to a sub-micron thic