A novel nanofabrication methodology for continuous, scalable, and geometry-tunable lithography is developed, named photo-roll lithography (PRL), by integrating photolithography with rollable processing. As a flexible mask attached to a quartz cylinder containing a UV source rolls over a photoresistcoated substrate, PRL realizes continuous photolithographic fabrication of various micro/nanoscale patterns with geometry that is tunable by controlling mask-substrate motions.

We demonstrate the continuous fabrication of large-area flexible metamaterial films via roll-to-roll (R2R) nanoimprint lithography (NIL) technique that can be conducted in an ambient environment at high speed. The plasmonic metal-insulator-metal structure is successfully fabricated by R2R NIL to continuously pattern the sub-wavelength scale metal disk array on flexible substrates. The patterned metal disks having varying diameters and sub-micron spacing with few defects lead to the desired broadband IR filtering performance at the designed dual-band, which correlates well with simulation analysis. Our method realizes a simple and high-throughput fabrication of plasmonic metamaterials for scalable and flexible optoelectronic and photonic applications.

We propose and demonstrate a new physical mechanism for producing liquid microjets by taking an optoacoustic approach that can convert light to sound through a carbon nanotube (CNT)-coated lens, where light from a pulsed laser is converted to high momentum carried by the sound wave. The CNT lens can focus high-amplitude sound waves to a micro-spot of < 100 μm near the air-water interface from the water side, leading to micro-bubbles in water and subsequent micro-jets into the air. Laserflash shadowgraphy visualizes two consecutive jets closely correlated with bubble dynamics. Due to the acoustic scattering from the interface, negative pressure amplitudes are significantly increased up to 80 MPa, even allowing homogeneous bubble nucleation. As a demonstration, this nozzle-free approach is applied to inject colored liquid into a tissue-mimicking gel as well as print a material on a glass substrate.

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Acoustically generated micro-bubble at solid surface is of paramount importance in applications such as selective surface treatment and controlled permeation of biological samples. However, surface heterogeneity (e.g., microsized nucleation sites) poses some challenges in controlling bubble, leading to uncontrolled heterogeneous bubbles. Here, we demonstrate controlled single micro-bubble rather insensitive to surface quality as a result of small focused acoustic spot (~200 μm) and high-amplitude negative pressure (~50 MPa) due to acoustic interference.