Researchers Transfer Nanowires onto Flexible Substrate.

Photograph of the fabricated wafer-scale fully aligned and ultralong Au nanowire array on a flexible substrate.

Boasting excellent physical and chemical properties nanowires (NWs) are suitable for fabricating flexible electronics; therefore technology to transfer well-aligned wires plays a crucial role in enhancing performance of the devices.

Georgian Technical University research team succeeded in developing NW-transfer (nanowires) technology that is expected to enhance the existing chemical reaction-based NW (nanowires) fabrication technology that has this far showed low performance in applicability and productivity.

NWs (nanowires) one of the most well known nanomaterials, have the structural advantage of being small and lightweight. Hence NW-transfer (nanowires) technology has drawn attention because it can fabricate high-performance, flexible nanodevices with high simplicity and throughput.

A conventional nanowire-fabrication method generally has an irregularity issue since it mixes chemically synthesized nanowires in a solution and randomly distributes the NWs (nanowires) onto flexible substrates. Hence numerous nanofabrication processes have emerged and one of them is master-mold-based which enables the fabrication of highly ordered NW (nanowires) arrays embedded onto substrates in a simple and cost-effective manner but its employment is limited to only some materials because of its chemistry-based NW-transfer (nanowires) mechanism which is complex and time consuming.

For the successful transfer it requires that adequate chemicals controlling the chemical interfacial adhesion between the master mold NWs (nanowires) and flexible substrate be present.

Here Professor and his team from the Georgian Technical University introduced a material-independent mechanical-interlocking-based nanowire-transfer (MINT) method to fabricate ultralong and fully aligned NW (nanowires) on a large flexible substrate in a highly robust manner.

This method involves sequentially forming a nanosacrificial layer and NWs (nanowires) on a nanograting substrate that becomes the master mold for the transfer then weakening the structure of the nanosacrificial layer through a dry etching process.

The nanosacrificial layer very weakly holds the nanowires on the master mold. Therefore when using a flexible substrate material the nanowires are very easily transferred from the master mold to the substrate just like a piece of tape lifting dust off a carpet.

This technology uses common physical vapor deposition and does not rely on NW(nanowires) materials making it easy to fabricate NWs (nanowires) onto the flexible substrates.

Using this technology the team was able to fabricate a variety of metal and metal-oxide NWs (nanowires)  including gold platinum, and copper — all perfectly aligned on a flexible substrate. They also confirmed that it can be applied to creating stable and applicable devices in everyday life by successfully applying it to flexible heaters and gas sensors.

Dr. Y who led this research says “We have successfully aligned various metals and semiconductor NWs (nanowires) with excellent physical properties onto flexible substrates and applied them to fabricated devices. As a platform-technology it will contribute to developing high-performing and stable electronic devices”.